The workplace contributes significantly to the total dose of daily noise to which a person is subjected. Therefore, millions of people around the world are exposed to potentially dangerous noise levels and consequently, there is an urgent, global need for legislation to adequately protect the auditory health of workers. Occupational noise legislation has been adopted in many of the countries with different degrees of comprehensiveness and varying levels of sophistication. This paper presents a global view of current legislation on occupational noise in the 22 countries that make up the Americas, that is, Latin America, Canada, and the United States. Upon analysis of the legislation, there are notable differences among countries in the defined values for permissible exposure limit (PEL) and exchange rate. Of the countries that have regulations, the majority (81%) use a PEL of 85 dBA. A PEL of 85 dBA and the 3-dB exchange rate are currently used by 32% of the nations in the Americas. Most nations limit impulsive noise exposure to a peak unweighted sound pressure level of 140 dB (or dBC), while a few use slightly lower limits. However, 27% of the countries in the region still have not established regulations with respect to permissible noise levels and exchange rates. This fact is leaving millions of workers in the Americas unprotected against occupational noise. Provide an overview and analysis of the current legislation on occupational noise in the 22 countries that make up the Americas. The information on legislation, regulations, and standards discussed in this paper were obtained directly from official government sources in each country, the International Labour Organization database, or through various colleagues in each country. (1) There are notable differences among countries in the defined values for PEL and exchange rate. (2) Of the countries that have regulations, the majority (81%) use a PEL of 85 dBA. A PEL of 85 dBA and the 3-dB exchange rate are currently used by 32% of the nations in the Americas. (3) Most nations limit impulsive noise exposure to a peak unweighted sound pressure level of 140 dB (or dBC), while a few use slightly lower limits. (4) 27% of the countries in the region still have not established regulations with respect to permissible noise levels and exchange rates. (5) Millions of workers in the Americas are unprotected against occupational noise.
Keywords: Noise exposure, noise-induced hearing loss prevention, occupational noise legislation, workplace noise
|How to cite this article:|
Arenas JP, Suter AH. Comparison of occupational noise legislation in the Americas: An overview and analysis. Noise Health 2014;16:306-19
| Introduction|| |
It is well-known that millions of people around the world are subjected to potentially dangerous noise levels, and a substantial number of them are suffering irreversible hearing loss. In this sense, the workplace contributes significantly to the total dose of daily noise to which a person is subjected. In addition, occupational noise-induced hearing loss continues to give rise to a significant number of claims for compensation and rehabilitation around the world. Therefore, there is an urgent, global need for legislation to adequately protect the auditory health of workers.
In the last several decades, many articles and research papers have been published about noise-induced hearing loss  and the effect of noise on speech perception in the workplace.  The hearing loss produced by exposure to noise depends on many factors, including the sound pressure level, spectral content, exposure duration, and the temporal pattern (continuous, varying, intermittent, or impulsive). The commonly accepted 8-h average A-weighted sound pressure level (permissible exposure limit [PEL]) is based on the exposure during a typical daily work shift. The use of A-weighted sound levels to predict the effect of noise on hearing is based on the response of the human ear at moderate sound pressure levels and is supported by numerous studies. ,,,
Permanent hearing loss produced by the exposure to excessive noise levels over extensive periods of time is called noise-induced permanent threshold shift (NIPTS). A relevant aspect of occupational noise legislation is the relationship between two or more sounds that are assumed to produce the same quantity of NIPTS when the noises differ in sound pressure level, duration, and temporal pattern. This relationship between noise level and exposure duration is commonly known as the exchange rate (q).
This "dose-trading relation" or "trading ratio" is expressed as the number of decibels by which the sound pressure level may be decreased or increased for a doubling or halving of the duration of exposure. Several studies support the fact that a value for the exchange rate of 3 dB (according to the "equal-energy rule") should be used in regulations rather than 5 dB, as it more accurately reflects the consequent hearing damage. ,,,
Impulse noise requires special attention, in that it concentrates high sound energy in a very short duration. In general, an impulse noise is described as having a rise time ≤1 s in duration, and if repeated, occurring at intervals >1 s. Impulse noise is also characterized by having a broad spectral content.
According to studies carried out on workers exposed to noise levels over 85 dBA in the United States (US),  the types of occupations that present the highest risk for hearing damage in terms of numbers of workers overexposed are: Manufacturing and utilities, transportation, military, construction, agriculture and mining. From the Australian data, it has been estimated that around 20.1% of the workforce regularly work in noise above a PEL of 85 dBA and 9.4% above an exposure of 90 dB.  A review on noise-induced hearing loss in Easter European States has also been published recently. 
Although similar studies do not exist for every country, it is plausible to assume that in an enormous economic area such as the Americas, which includes Latin America, the Caribbean, Canada, and the US, work environments with high noise levels are common, and each one represents an important risk to the auditory health of the workers.
A World Health Organization study on the burden of disease associated with hearing impairment from occupational noise  reported that overall in the Americas, more than 300,000 disability-adjusted life years were lost to noise-induced hearing loss. Canada and the US accounted for almost half of the years of healthy life lost, as they have large industrial populations.
Despite the recent economic crises in Europe and the USA, Latin America has seen a notable economic boom in the past several years. Capital investment in Latin America has increased significantly, and many companies have installed new manufacturing industries, implementing huge mining and outsourcing projects, among others.
Globalization and free trade between countries encourages companies to develop industries overseas and consulting businesses to operate beyond their borders. However, every enterprise must comply with safety legislation and regulation in the workplace, which is different in every country. Multinational corporations and safety and health professionals must be aware of how the regulations differ from those in their home countries.
This paper presents a global view of current legislation on occupational noise in the Western Hemisphere, a part of the world that encompasses a large geographic area, and a socially diverse population that includes more than 900 million inhabitants. Economically speaking, this zone is highly heterogeneous, including both industrialized and developing countries.
This paper covers the 22 countries that make up the Americas, that is, Latin America, Canada, and the US. Some small Caribbean countries have been omitted because of the lack or paucity of legislation/regulation on occupational noise. Puerto Rico has also been excluded, due to the fact that it is a territory of the US, and therefore adopts US legislation. The information on legislation, regulations, and standards discussed in this paper were obtained directly from official government sources in each country, the International Labor Organization database, or through various colleagues in each country.
| Legislation on Occupational Noise for Each Country|| |
In the field of occupational noise, although they may have different meanings, the words legislation, regulation and standard are often used interchangeably, which can produce confusion. In the majority of countries, legislation represents a type of law, usually general and comprehensive in its coverage; and this is generally developed by legislative authorities such as members of congress or elected representatives. A regulation is a rule or an order placed by the executive or administrative branch, and is considered law. On the other hand, a standard is a codified set of rules or guidelines that is often an acknowledged measure of comparison for quantitative or qualitative values. Regulations can incorporate standards to precisely define particular actions required by such laws. 
In some countries, regulations consist of sets of guidelines, which are recognized as the country's standard and not rigorously enforced. Sometimes a nation's noise standard will include guidelines for explanatory purposes.
In Spanish speaking countries, it is common to use the word decree to define a document adopted by the executive branch of government and which has the force of law. In this paper, the authors attempted to use the terms employed by the specific nations when referencing their own codes.
In 1977, the General Conference of the International Labor Organization adopted Convention 148, regarding the protection of workers against occupational hazards due to air pollution, noise, and vibration in the workplace.  This convention established in 24 articles the bases of legislation, considering measures of prevention and protection, the establishment of criteria and exposure limits for occupational noise, the promotion of occupational health research, and official recognition and concern for the health of the exposed workers. The ratification of this convention has generated similar legislation in several different countries. Others have adopted the convention, limiting it to only some of the pollutants such as air and noise, but leaving out vibration.
One of the most commonly used standards is ISO 1999.  This international consensus standard can be used to predict the amount of hearing loss expected to occur in various centiles of the exposed population at particular audiometric frequencies as a function of exposure level and duration, age and sex. The standard provides a complete description of NIPTS for various exposure levels and exposure times.
It is important to note that ISO 1999 does not explicitly establish limits for the level of occupational exposure, which is defined in the occupational noise legislation or regulation in each particular country. In some countries, technical standards may be typically direct copies of the ISO standards, without the benefit of enabling legislation or regulation.
The most relevant acoustic factors in occupational noise regulation are: The normalized 8-h PEL, the exchange rate (q), the maximum upper limits for exposure to impulsive sounds, and requirements for engineering controls. Sometimes efforts are made to reduce noise levels in the workplace to the lowest technically and economically reasonable values, even when there is no risk of long-term hearing damage. In addition, it is necessary to include requirements for a long-term noise control program where the level of the daily exposure exceeds the limits, use of personal hearing protection devices, and audiometric testing programs, that is, preplacement audiometric testing at the time of hiring a new worker and periodically during employment. 
In the next subsections an overview of current legislation on noise in the workplace environment is presented for each country.
In Argentina, Law 19.587 of 1972 determines the basic requirements with respect to general hygiene and safety conditions in the workplace.  The technical specifications of this law were given in a resolution in 1979, which established the exchange rate (q) and PEL values of 3 dB and 90 dBA, respectively. The law was subsequently modified by resolution 295 of 2003, which included ergonomics, radiation, thermal stress, chemical substances, biological control, acoustics, and vibration. 
The current Argentine standard establishes a PEL of 85 dBA with a q of 3 dB, measured using the slow response of a sound level meter, with a maximum exposure level of 124 dBA. Exposure to continuous, intermittent, or impulse noise over 140 dBC is not permitted. The use of a dosimeter or an integrating sound level meter for noise over 120 dB is recommended. In the case of impulse noise, exposure is not permitted without hearing protection above a peak sound pressure level of 140 dBC.
When workers are exposed to levels that are equal to or greater than these limits, a complete hearing conservation program is required, which includes audiometric tests.
The standard establishes requirements for very low-frequency noise: For frequencies between 1 and 80 Hz, the sound pressure level must not exceed 145 dB, and the sound pressure across all these frequencies must be <150 dB. This requirement is based on evidence that sounds in the frequency band between 50 and 60 Hz can cause discomfort due to chest resonance. The standard requires the reduction of the sound pressure level until the problem disappears. Finally, the standard establishes the limit values in dB for ultrasound for each third-octave band center frequency between 10 and 100 kHz, both for measurements in air and in water.
The Bolivian legislation is contained in the Decree 16998 of 1979, which establishes the Law of General Hygiene, Occupational Safety and Wellness in the workplace.  In this law, various factors are considered, such as space, lighting, ventilation, fire prevention, the handling of dangerous substances, and radiation.
Occupational noise is addressed in only three paragraphs in a section about physical hazards from noise and vibration. The law requires that in every workplace where workers are subjected to excessive noise and vibration, the intensity of these factors must be reduced to acceptable levels through adequate engineering controls. In addition, exposed workers must be equipped with protection against noise and vibration.
The Law also requires that the noise risk should be evaluated by technical personnel designated by a competent authority and that all workers exposed to excessive noise should be provided with permanent, systematic medical care.
Recently, the Bolivian Institute for Standardization and Quality issued the standard on occupational noise NB 510001.  The standard calls for a PEL of 85 dBA with a q of 3 dB. For individuals without hearing protection, exposure above 105 dBA is not permitted.
Engineering control measures and hearing conservation programs (including monitoring, training, initiating an audiometric testing program, using hearing protectors, and notifying employees) must be implemented when time-weighted average levels exceed 85 dBA for 8 h (corresponding to a dose of 100%).
The standard includes four annexes. Annexes A and B concern guidelines for developing measurements, noise dose computation and technical reporting. Annex C concerns the selection of hearing protection equipment. The last annex, although not mandatory, states specifications for tonal air audiometries that must be performed periodically and the background noise requirements where audiometries are conducted.
The standard does not limit impulsive noise exposure to a particular peak sound pressure level.
Brazil ratified ILO Convention 148 on January 14, 1982. In 1978, Brazil enacted Law 3214, which is composed of 29 standards called "NR." Each NR is related to a type of health and safety regulation. These standards have been updated through the years, and there are now 33 NRs in place. Various risk agents and their exposure limits are found in NR 15.  In the case of occupational noise, the law establishes PEL of 85 dBA with q of 5 dB. Continuous levels must be measured using the slow response of a sound level meter. For individuals without hearing protection, exposures above 115 dBA are not permitted.
An annex of NR 15 requires impulse noise to be measured using the sound level meter's impulse response mode. The maximum limit in this case is 130 dB linear (measured in the impulse mode of the sound level meter) or 120 dBC (measured using the fast response of a sound level meter).
NR 6 concerns hearing protection requirements, and NR 17 establishes acoustic comfort limits for jobs that require mental concentration. NR 9, updated in 1994, outlines prevention programs for environmental risks. Noise control measures must be implemented when the time-weighted average levels exceed 80 dBA for 8 h (corresponding to a dose of 50%).
The Canadian government issues legislation for occupational noise exposure, but each of the 13 provinces is permitted to set its own limits; thus, there is some variation among them. The Federal regulation  calls for a PEL of 87 dBA with a q of 3 dB. There is no separate requirement for impulse noise because it is integrated into the dose for continuous and intermittent exposure. Most of the provinces use a q of 3 dB except for the North West Territories, Quebec, and Nonavut (nonmining), which use 5 dB. Aside from the Federal government (87 dBA) and Quebec (90 dBA), all of the provinces use a PEL of 85 dBA. The action level for the Federal regulation is 84 dBA. Some provinces use an action level of 85 dBA, and Manitoba and Saskatchewan use 80 dBA. Several provinces limit peak sound pressure levels for impulsive noise to 140 dB, and four limit the numbers of impulses allowed at this level. References for noise legislation for the various provinces and territories may be found on the Internet. 
In Chile, basic sanitary and environmental conditions in the workplace are regulated by Decree 594 of 1999. Articles 70-82 contain regulations for occupational noise and the technical requirements of dosimeters and integrating sound level meters.  A PEL of 85 dBA with a q of 3 dB and workplace exposures over 115 dBA are not permitted without hearing protection.
An 8-h work shift characterized by impulsive noise cannot exceed a time-weighted average level of 95 dBC, measured at the worker's ear. In no case may workers in any job be exposed to peak sound pressure levels over 140 dBC.
In 2011, the Ministry of Health approved Technical Standard 125, which established minimum standards for hearing loss prevention due to exposure to noise in the workplace.  This standard replaced an older version from 1997. This document establishes an 8-h time-weighted action level criterion of 82 dBA, which corresponds to a dose of 50% of the PEL. The action level for impulse noise is a peak level of 135 dBC.
If these action levels are exceeded, immediate noise control measures must be implemented within a 6 month period if the dose exceeds 1000%, or within a year if the dose is <1000%. Furthermore, the action level requires a hearing conservation program that includes hearing evaluation (audiometry), epidemiological analysis, occupational history review, and medical evaluation. Audiometric evaluations must be conducted upon the initiation of noise exposure, and periodic audiometric tests are required according to the level of noise dose: Every 3 years for a dose between 50% and 100%, every 2 years for a dose between 100% and 1000%, and every year for doses over 1000%. In the presence of impulse noise ≥135 dBC, audiometric tests must be performed every 6 months.
Colombia enacted standards on hearing protection and occupational noise in Regulation 8321 of 1983. These requirements include community noise and occupational noise in the same document.  Chapter 5 addresses noise in the workplace. The PEL and q were 90 dBA and 5 dB, respectively, but the legislation was modified in 1990 by Regulation 1792, which calls for a PEL of 85 dBA with q of 5 dB. Exposure above 115 dBA is not permitted.
Article 45 considers impulse noise with limit values of linear sound pressure level in function of the number of daily impacts permitted, in concordance with a table of three rows. For 10 daily impacts, the limit is 140 dB, for 1,000, it is 130 dB, and for 10,000, it is 120 dB. It is not specified if the permitted values must be extrapolated for impacts/day when the sound pressure level values are not exactly those in the table. In all cases, it is specified that the maximum sound pressure level should not exceed 140 dB.
Control measures must by applied when the permissible values are exceeded, and it is indicated that a hearing conservation program must be enacted for all workers who are subjected to noise levels close to, or above the permitted limit values. Noise control measures must be placed at the source, in the transmission path, and at the receptor. The rest of the regulation explains the details that should be included in the hearing conservation program, including the specifications for tonal air audiometries that must be conducted periodically. Furthermore included in the standard are the background noise requirements where audiometries are conducted.
Costa Rica ratified ILO Convention 148 on June 16, 1981. There are two main documents in the Costa Rican legislation about occupational noise. The first is Decree 10541-TSS of 1979 about the regulation and control of noise and vibrations.  In this decree, it is established that "noisy" places are those that produce noise above 85 dBA. Workers without hearing protection are not permitted in places with levels above 85 dBA of continuous noise or 90 dBA of impulse noise. The decree also sets forth sanctions that can fully or partially paralyze the production activity if this regulation is broken.
Second, the Institute of Technical Standards enacted Code INTE 31-09-16-00 in the year 2000, which established the security and hygiene conditions in the workplace where noise is generated.  The standard indicates a PEL of 85 dBA with a q of 3 dB.
The maximum permissible level is 115 dB, and exposure is not permitted for values over 105 dBA, although, subsequently, a table is presented that allows values of up to 112 dBA. The case of impulse noise is not addressed in the standard. Outlined as well is an action level of 82 dBA, at which prevention methods must be developed. At 85 dB, a hearing conservation program must be implemented, including hearing tests, covering all personnel. The standard establishes the types of required medical tests, including tonal air and bone conduction audiometry and logo audiometry.
Cuba ratified ILO Convention 148 on December 29, 1980. In general, Law 13 of hygiene and protection in the workplace established in Cuba the obligation of the administration to avoid noise production by any means necessary.  This law was complemented by Decree 101 on hygiene and protection in the workplace. To define the technical aspects with respect to occupational noise, in 2011, the Cuban National Bureau of Standards published the document NC871:2011  that replaced another standard from 1980. This standard is mandatory by law.
The standard is based on the Noise Reduction Criteria and establishes permissible exposure levels and values of NdB for different types of work-related activities. In this sense, for all work positions, a PEL of 85 dBA with a q of 3 dB is established. In every case, workers are prohibited to stay in areas with sound pressure levels above 135 dBA, measured in any octave-band center frequency. The most restrictive level is of 50 dBA (45 NdB) and corresponds to work related to reception and processing of information, such as teaching classes, medical activities, scientific study, and design work.
In the case of impulse noise, in workplaces where more than one event per shift occurs, a maximum number of permissible impacts is established for a shift of 8 h. For 10 impacts, a peak level of 140 dB is permitted, and for 100, it is 130 dB, for 1,000, it is 120 dB, and for 10,000, it is 110 dB. There are formulas presented to calculate the permissible levels for continuous and impact noise, although one of the formulas does not fit the values given in a table. Furthermore, it is established that no person, worker or not, should expose themselves to values ≥135 dBA or 135 dB.
Noise control measures must be applied to comply with the limit values, and personal hearing protection must be provided when noise control is technically impossible. In noisy work environments, pre- and post-employment and periodical medical exams are mandatory, including audiometries. Upon detecting a permanent hearing threshold shift >35 dB at a frequency of 4000 Hz, the worker must undergo more specialized exams.
The Dominican Republic established health and safety regulations in the workplace in Decree 522-06 of 2006. In this regulation, a chapter is included about physical, chemical, and biological risks, where occupational noise is mentioned.  The law establishes that in jobs in which the daily noise level or the peak level surpasses 80 dB or 140 dB, respectively, the reasons will be analyzed, and an engineering noise control program will be developed. No type of weighting is indicated for the above levels, nor is the definition of the equivalent daily level included.
In places where it is technically not possible to control noise, annual hearing tests must be conducted. In addition, the use of hearing protection is mandatory when the noise level exceeds 80 dBA. Workplaces that present high noise exposure levels must also be signalized for restricted access.
Ecuador ratified ILO Convention 148 on July 11, 1978. In Ecuador, Decree 2393 of 1986 contains the health and safety regulations for workers, and likewise, the guidelines for occupational environmental improvement in the workplace.  Article 55 is related to noise and vibrations. The standard calls for a PEL of 85 dBA and a q of 5 dB, and the levels should not surpass 115 dBA (in the slow meter response) in any type of work. For certain occupational activities that require attention and concentration, the value should not be >70 dB (it is not specified if these are A-weighted levels).
For impulse noise, the maximum sound pressure exposure for each work shift of 8 h depends on the total number of impacts during each shift according to a table that indicates a maximum permissible level of 140 dBA for 100 impacts, 135 dB for 500, 130 dB for 1,000, 125 dB for 5000, and 120 dB for 10,000 impacts. It is not specified if the permitted values should be extrapolated for impacts/day when the values of sound pressure levels are not exactly those of the table. It is indicated that the hearing of workers subjected to these levels should be checked annually.
Article 179 covers hearing protection, and it establishes that personal hearing protectors are obligatory when the permitted levels are surpassed. Finally, the requirements and appropriate usage of the hearing protection is included. The legislation does not contain mention of a hearing conservation program.
The first reference to occupational noise in the legislation of El Salvador is found in Decree DE 7 of 1971, which defines general regulations for security and hygiene in the workplace.  Chapter V has two articles, the first of which establishes that the National Social Security Department shall dictate the necessary measures to protect workers against noise in excess of 80 dB. However, it is not specified if this level corresponds to an equivalent noise level or the time of exposure.
Finally, it is established that in places where noise is a nuisance, the ceilings must be covered with a sound absorbing material. In 2010, Decree 254 of the General Law of risk prevention in the workplace instructs that the maximum permissible noise levels should be incorporated in future regulations. 
Guatemala ratified ILO Convention 148 on February 22, 1996. Guatemala has an old regulation regarding hygiene and safety in the workplace that was enacted in 1957 and is still valid.  This regulation establishes standards and obligations for workers, intermediaries, and contractors who perform jobs in industry, agriculture, commerce, and any other type of production. In this regulation, general working conditions are described, and reference is made to occupational risks, such as electricity, dangerous substances, and some machinery. The topic of noise is not included within the regulation.
The only reference found regarding noise in the Guatemalan legislation corresponds to the ratification in 1996 of Convention 148 of the ILO. Recently, a new legislation project is underway regarding the regulation. This project is still in the approval process in Congress, and it is not known if noise will be included or in what form.
Legislation on occupational noise in Honduras is contained in General Regulation STSS-053-04 about preventive measures for accidents in the workplace and occupational health enacted in 2004 by the Social Security and Labor Secretary.  The subject of occupational noise is included in articles 351 through 360. The regulation establishes a PEL of 85 dBA with a q of 5 dB and a maximum exposure level of 115 dBA without hearing protection.
Regarding exposure to impulse noise, the maximum sound pressure level that should not be surpassed in any workplace is 140 dB.
In addition, it is stipulated that hearing tests must be conducted every 5 years and that hearing protection must be provided for workers subjected to noise levels at or above 80 dBA and <85 dBA during 8 h or equivalent exposure.
The mandatory use of hearing protection and hearing tests each year are required for workers exposed to levels above 85 dBA over 8 h or an equivalent exposure or when at any moment the noise level is above 140 dB, measured on a linear scale. Additionally, there must be a hearing conservation program implemented that must include:
- Environmental analysis of noise exposure;
- Systems to control noise exposure; and
- Hearing tests upon hiring, during employment, and upon termination.
The conditions for safety and hygiene in the workplace are given in the official Mexican standard NOM-011-STPS of 2001.  This standard replaced the older standard of 1994. The standard establishes a PEL of 90 dBA and a q of 3 dB. In no case should there be an exposure without hearing protection at levels above 105 dBA.
Noise control measures must be applied when the exposure levels pass the permissible levels. A hearing conservation program must be implemented when the level is ≥85 dBA. The program must take into account the nature of the work; the influencing characteristics of the emission source (magnitude and frequency components of the noise); the duration and frequency of the worker exposure; and the possible health alterations. Likewise, the general and specific methods of prevention and control are included.
The standard possesses various appendices in which the procedures are explained in a detailed manner for several variables, such as the calculation of the noise exposure level from the measurements made in the actual work location with a sound level meter and dosimeter, the determination of the sound pressure level in octave-bands, and the determinations of the reduction factor (R) given by the attenuation provided by the hearing protector. The characteristics and requirements for the type of hearing protectors that should be provided for the workers are given in another standard (NOM-017-STPS-1993).
The standard does not specify permissible values for impulse noise.
In Nicaragua, General Law 618 was enacted in 2007, which refers to hygiene and safety in the workplace.  Decree 96-2007 of the same year corresponds to the regulation of the general law.  The regulation indicates some safety and hygiene measures in the workplace, making reference to the respective technical standards. Occupational noise is not considered in these guidelines. The rights and duties of all employees are also outlined, along with the applicable sanctions.
There exists only one reference to occupational noise in Article 121 of Law 618. In this reference, it is specified that obligatory use of hearing protection is mandatory for a level of 85 dBA over 8 h of exposure. The same is established for impulse noise greater than a 140 dBC peak. Within the required medical exams, there is no explicit mention of audiometry. The exchange rate is also not mentioned.
In 2002, the government of Panama enacted Decree 306 that adopted the regulations for noise control in public spaces, residential areas, and occupational environments.  This law establishes maximum permissible levels for a work shift of 8 h for three types of jobs:
- Jobs with constant and intense mental activity (50 dBA),
- office work or similar (60 dBA), and
- Others (85 dBA).
The same law establishes that businesses must apply technical regulation RT 44-2000, which outlines workplace hygiene and safety in occupational environments, where noise is generated. This law was approved in 2000. The regulation calls for a PEL of 85 dBA and a q of 5 dB. The maximum permitted value is 115 dBA. Exposure to noise levels over 130 dBA is not permitted in any case without personal hearing protection.
Within the criteria of personnel selection, an auditory evaluation of applicants is required in places that surpass levels of 85 dB. Air and bone audiometry is required between 125 Hz and 8 kHz and 250 Hz and 6 kHz, respectively. Logoaudiometry is required, as well as the determination of temporary threshold shift 2 min after exposure to noise. These exams indicate the aptitude of the workers for exposure to a noisy environment.
Also, obligatory is the training of personnel on at least one occasion annually. This training must be about occupational noise, its control, and hearing protection. Decree 306 requires that noise control engineering techniques are implemented when the noise level is above 85 dBA for 8 h. If the levels rise above the permissible values, a hearing conservation program must be implemented as well. This is further detailed within the regulation.
The regulation does not specify values for impulse noise.
Occupational noise is considered in Decree 14390 of 1992, which approves the General Technical Regulation of Safety, Hygiene and Medicine in the Workplace.  Article 232 establishes a PEL of 85 dBA with a q of 5 dB and a maximum exposure level of 115 dBA.
For impulse noise, the limit values of the linear sound pressure level in function of the number of daily impacts permitted are defined according to a table with three rows. For 100 daily impacts, the limit is 140 dB, for 1000, it is 130 dB, and for 10,000, it is 120 dB. It is not specified if the permitted daily values must be extrapolated when the sound pressure level values are not exactly those of the table. Finally, article 252 provides indication about the required types of hearing protection devices.
In Peru, occupational noise laws are scarce. In 2005, regulation of occupational health and safety came into effect with Decree 009-2005-TR,  which was modified in 2007. This regulation has the principal objective of promoting a culture of risk prevention in the country, establishing rights and obligations of employers and employees. Furthermore, it defines terms relevant to safety and hygiene in the workplace. However, it does not establish any type of limit for any pollutant.
Using a legal resolution from the Ministry of Health, 457 of 2007, a bill was presented about the regulation of occupational noise.  However, no laws have been enacted to this effect.
In 2001, the Peruvian government enacted Decree 046-2001-EM about safety and hygiene in mining.  This law is obligatory for all companies that conduct mining activities or any external company that is contracted by them. In subchapter 9 on occupational health and the control of physical agents, a PEL of 85 dBA with a q of 3 dB were established, with a maximum exposure level without hearing protection of 100 dBA. No type of exposure over 140 dBA is permitted.
Trinidad and Tobago
The Occupational Safety and Health (OSH) Act of Trinidad and Tobago issued in 2004 and amended in 2006 focuses on promoting the safety, health, and welfare of workers at industrial organizations.  The act lists hearing impairment caused by noise as a disease caused by physical agents. In part VI on health, there is a short section on noise and vibration. Basically, the act just states that the employer shall take adequate steps to prevent employee hearing impairment caused by noise. In addition, the employer is responsible for:
- Ensuring that hearing protectors are worn by employees at all appropriate times,
- Arranging for initial and periodic audiometric tests,
- Keeping a record of the tests, and
- Arranging for hearing conservation programs.
There is neither a regulation nor standard for establishing the values of PELs and an exchange rate.
In the USA, several federal agencies have issued occupational noise regulations. The Occupational Safety and Health Administration (OSHA) in the Department of Labor was the first agency to promulgate a noise standard for general industry, and as a result, other agencies, as well as other nations, have often followed its lead.
Occupational safety and health administration
In 1970, the US Congress passed the OSH Act (Public Law 91-596), giving OSHA the authority to regulate hazardous substances in the workplace, including exposure to noise. However, before the passage of this legislation, the Department of Labor issued a noise regulation (29CFR 1910.95), and in 1971, this regulation became applicable to all industry engaging in interstate commerce. It called for a PEL of 90 dBA with a q of 5 dB, the reduction of noise levels to the PEL by engineering or administrative controls whenever feasible, the provision and wearing of hearing protection devices above the PEL, and in section (c), the conducting of a "continuing, effective hearing conservation program" for employees exposed above the PEL. 
The noise regulation was amended in 1981 to dictate specific obligations at an action level of 85 dBA.  At this action level, OSHA requires noise measurement, the use and care of hearing protection devices, audiometric testing, employee training and education, and record keeping. The agency promulgated a revision of the hearing conservation amendment in 1983, which is still currently in effect.  This amendment replaced section (c) of the noise standard. However, sections (a) and (b) detailing the PEL and the requirement for feasible engineering or administrative controls remained the same.
The OSH Act permits state agencies to issue their own regulations, as long as these regulations are at least as protective as those promulgated by the federal OSHA. About half of the states have selected to do this, whereas the rest chose to rely on federal enforcement.
Occupational Safety and Health Administration has issued a separate noise regulation (29 CFR 1926.52) for the construction industry, although it has not yet been amended for specific requirements for hearing conservation programs. Occupational settings not covered by OSHA's noise regulations include agriculture and oil and gas well drilling and servicing.
US Mine Safety and Health Administration
In 1969, the US Congress enacted the Federal Coal Mine Health and Safety Act, and in 1977, it enacted the Federal Mine Safety and Health Amendments Act. Thus, Mine Safety and Health Administration (MSHA) has promulgated noise regulations for coal mines and several regulations for metal and nonmetal mines. In 1999, MSHA issued a single comprehensive noise regulation that applies uniformly to all types of mining (30 CFR Part 62). The newer regulation calls for a PEL of 90 dBA, a q of 5 dB, and an action level of 85 dBA. Many of the hearing conservation requirements are similar to those in the 1983 OSHA noise regulation, except for the addition of requirements for dual hearing protection at average exposure levels ≥105 dBA and for the provision that mine operators provide miners with a choice of at least 2 plugs and 2 muffs.
Another difference between the MSHA and OSHA regulations is that MSHA's requirement for "all feasible engineering and administrative controls to reduce the miner's noise exposure to the permissible exposure level" is written directly into the revised standard, whereas OSHA depends on the original standard for this section. The result is that engineering noise control has been more widely implemented for mining than for general industry. Hearing protectors are not considered a substitute for engineering and administrative controls.
United States Department of Transportation
Within the US Department of Transportation, the Federal Motor Carrier Safety Administration regulates the noise exposure of truck and bus drivers. In 2011, the agency issued a revised noise regulation (49 CFR 391.49), calling for a maximum noise level of 90 dBA at the driver's position with a permitted 2 dB tolerance, making the effective enforcement level 92 dBA. The regulation does not specify a time-weighted average level, but the maximum permissible driving time is 10 h. The agency also issues hearing threshold level requirements for operators of trucks and buses.
The Federal Railroad Administration, which is another agency within the Department of Transportation, has issued noise exposure regulations covering railroad workers and qualification requirements for locomotive operators. The agency issued a detailed noise exposure and hearing conservation regulation in 2006 (49 CFR 227). Most of the requirements are similar to OSHA's, with some variations.
United States Department of Energy
In 2006, the US Department of Energy issued a final rule for worker safety and health, which applies to all contractors doing business at Department of Energy sites (10 CFR 851). Although exposure limits are not specifically stated in the regulation, Section 851.23 requires all contractors to comply with the ACGIH ® threshold limit values for chemical substances and physical agents when these limits are more protective than 29 CFR 1910 (meaning OSHA regulations). This provision is currently being enforced for noise, including a PEL of 85 dBA with a q of 3 dB.
United States Coast Guard
The US Coast Guard has issued guidelines for crews on board US commercial vessels (NVIC 12-82). The guidelines recommend the evaluation of crew members' 24-h exposure levels, a criterion level (L 24 ) of 82 dBA, the wearing of hearing protectors at L 24 of 85 dBA, and an action level of L 24 of 77 dBA, at which hearing conservation programs should be provided. These criteria are equivalent to OSHA's requirements normalized on a 24-h basis.
United States National Aeronautics and Space Administration
National Aeronautics and Space Administration (NASA) has issued detailed standards covering all of its employees except those on space flights. The agency uses a criterion level of 85 dBA, an action level of 82 dBA, and a q of 3 dB. Impulse or impact noise up to peak levels of 140 dB must be included in the measurement of dose. Primacy is given to engineering and administrative controls, and personal protective equipment should be relied upon only temporarily or if controls are not feasible or practical.
National Aeronautics and Space Administration's range of allowable noise exposures extends from 20 h to 10 min at 81 dBA to 15 min at 100 dBA. Exposures exceeding these criteria must be controlled, reduced, or eliminated through a hierarchical combination of engineering controls, administrative controls, and hearing protection. Because of its scope and protective aspects, this program could serve as a model hearing conservation program for other agencies.
United States Department of Defense
The Department of Defense (DOD) issues "instructions" periodically on matters of safety and health for use by all three branches of the US Armed Services. Each branch or DOD "component" (Army, Navy, and Air Force) may issue its own regulations, as long as they comply with the basic DOD Instruction. A revised Instruction was issued in 2010 for the conduct of hearing conservation programs (DOD Instruction 6055.12). It calls for a PEL of 85 dBA with a q of 3 dB and peak sound pressure levels not to exceed 140 dBC.
The DOD Instruction also gives requirements for ultrasonic exposure, noise assessment, and engineering control measures for new systems that are likely to produce overexposure or impairment of communication and hazard signs for noisy areas. Tools or equipment producing noise levels >85 dBA must be marked or labeled. Engineering controls are the primary choice for limiting exposure, all practical design approaches must be explored, and new equipment considered for purchase must have the lowest levels technologically and economically feasible.
Uruguay ratified ILO Convention 148 on September 5, 1988. The legislation in Uruguay consists only of what is established in Decree 406/88 of 1988, which regulates occupational health, hygiene, and safety in the workplace.  In this law, there is a chapter about physical risks, in which noise is included. In accordance with this decree, the maximum noise level allowed is 85 dBA in any work environment that presents a health risk to the workers.
This legislation demands that enterprises adopt prevention measures or eliminate or reduce sound intensity, unless such measures would not be easy to apply, in which case the authorities must be informed about the situation. Additionally, it is stipulated that in cases where the noise level is >85 dB, workers must be given hearing protection, and in this case, initial and ongoing hearing tests must be conducted for all employees. It is not specified in the legislation if the 85 dBA level corresponds to an equivalent value or an accumulated exposure over time. Nothing is included about impulse noise or the time intervals between worker hearing tests.
Recently, Decree 143 of 2012 was enacted, which reduced the maximum noise level allowed to 80 dBA.  This limit was already in place for the agriculture industry.
In Venezuela the standard COVENIN 1565 of 1995 includes references to occupational noise, hearing conservation programs, permissible levels, and evaluation criteria.  This normative is obligatory in concordance with a general law regarding prevention, conditions, and environment in the workplace. This law was enacted in 2005.  The Venezuelan standard establishes a PEL of 85 dBA with a q of 3 dB. In no case must there be exposure over 140 dBA. It is recommended to use a dosimeter or integrating sound level meter for noise above 120 dB. For workers without any type of hearing protection, exposure to peak sound pressure levels above 140 dBC is not permitted.
Exposure to continuous noise levels ≥85 dB without using hearing protection is not permitted. Hearing protectors must comply with what is specified in another standard (COVENIN 871:78).
A hearing conservation program must be implemented when the sound level limits are exceeded. The hearing conservation program must have the following elements: Worker training, evaluation of the exposure levels, medical screenings (including audiometries), use of hearing protection, labeling of noisy areas, and noise control measures.
The requirements of the audiometries are outlined in a detailed manner, and they must be performed after at least 14 h without any exposure to levels equal or above 85 dBA. The background noise level requirements are indicated for rooms in which the audiometry will take place.
The standard also recommends the noise levels for typical workplaces according to the NR curves. In these workplaces where intellectual work predominates, noise levels should be kept under NR55.
Finally, evaluation methods are recommended that precisely detail the requirements for the measuring equipment, calibration, frequency analysis, dosimeters, and noise reports. The last annex of the standard is dedicated to noise maps, which are suggested in the methods of noise evaluation.
| Discussion|| |
[Table 1] and [Table 2] summarize the main features of legislation for each country.
|Table 1: PELs, exchange rates, and other requirements for noise exposure according to nation|
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|Table 2: Noise exposure limits for impulse/impact noise according to nation|
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It is important to mention that it was much more difficult to find legislation related to workplace noise rather than community noise in the analyzed countries. This indicates that community noise tends to be considered more important than workplace noise by governments, given the pressure by environmental groups and the large number of people affected by noise pollution in big cities.
The degree of development of occupational noise regulation varies greatly between the countries considered in this study. In several cases, noise is considered one of the causative agents of adverse effects on the health of workers and defined in general legislation on hygiene and safety conditions in the workplace. Thus occupational noise legislation has been adopted in many of the countries with different degrees of comprehensiveness and varying levels of sophistication.
A direct relationship between the ratification of ILO Convention 148 and the development of legislation is not apparent. The majority of countries have promulgated occupational noise regulations without ratifying the Convention. On the other hand, Guatemala and Uruguay have not yet produced legislation regarding this topic, even though they ratified the Convention many years ago.
As of August 2013, six countries out of 22 have ratified the Convention. It is important to note that the ratification of this Convention by an ILO Member State involves the obligation to apply its provisions in law and in practice.
It was not possible to find any legislation about occupational noise in El Salvador, Guatemala, or Trinidad and Tobago. Although a decree does exist in Uruguay that establishes a maximum limit, neither an equivalent value nor a duration of exposure is specified. Clearly, this is inadequate because the legislation should define a specific limit for the exposure level of a worker and not just the sound pressure level that exists in a workplace. 
Upon analysis of the legislation, there are notable differences among countries in the defined values for PEL and exchange rate. Of the countries that have regulations, the majority (81%) use a PEL of 85 dBA. Of these, 54% use a q value of 3 dB, and the rest use a q value of 5 dB. Only two countries define a PEL of 90 dBA: Mexico, which uses a q of 3 dB, and the USA, which uses a q of 5 dB. The Canadian federal regulation is the only legislation that establishes a PEL of 87 dBA with a q of 3 dB. However, a significant number of countries in the region (27%) have not yet defined a specific value of PEL or q. [Figure 1] shows the distribution of the PEL and q values in the legislation of the countries of the region.
|Figure 1: Permissible exposure limit and exchange rate (q) values in the legislation of the countries of the Americas|
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[Figure 2] shows a comparison of duration per day to allowable noise exposure level (100% dose) for different values of PEL and q as used in national standards.
|Figure 2: Comparison of duration per day to allowable noise exposure level (100% dose) for different values of permissible exposure limit and q as used in national standards|
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[Figure 2] shows that the use of an 85 dBA PEL with a q of 3 dB, provides the best protection to workers. The Mexican legislation (PEL 90 dBA and q of 3 dB) provides better protection than legislation using a PEL of 85 with a q of 5 dB, but only when the noise level is above 97.5 dBA. Below this level, less protection is provided.
Canadian federal law, (PEL 87 dBA and q of 3 dB), offers better protection than the regulations using a PEL of 85 dBA with a q of 5 dB, at least when the noise level is >90 dBA.
It is clear that the OSHA legislation offers less protection to workers at all durations than any other system. For a worker exposed to noise for only 15 min, OSHA permits a sound level 15 dBA greater than, for example the maximum level permitted in Chile, 13 dBA greater than permitted in Canada, 10 dBA greater than permitted in Mexico, and 5 dBA greater than the permitted level in Brazil.
Few countries have defined "action levels" lower than the PEL value established in their legislation, although the majority establish regulations requiring engineering controls and hearing conservation programs when noise exposures are above the permitted levels.
Some nations have promulgated separate standards or regulations for hearing protection devices (such as Brazil, Chile, Mexico, and Venezuela) and for hearing conservation programs (such as Brazil, Chile, and the US).
The legislation in Argentina explicitly includes requirements for exposure to infrasound and ultrasound in the workplace. The instructions given by the US DOD also give requirements for ultrasonic exposure.
Noise regulations in several nations treat impulse noise separately from continuous noise. [Table 2] shows some features of legislation on impulse noise according to nation. A common approach in some countries (usually those using a q of 5 dB) has been to limit the number of impulses at a given peak sound pressure over a workday, although the exact figures vary slightly. Alternatively, other nations have considered impulse noise jointly with any continuous noise.
Most nations limit impulsive noise exposure to a peak unweighted sound pressure level of 140 dB (or dBC), while a few use slightly lower limits (Brazil at 130 dB or 120 dBC, and Cuba at 135 dB). Quite a few limit continuous noise to 115 dBA, while some use lower limits (e.g. Mexico and Bolivia at 105 dBA) and some higher limits (e.g., Canada at 120 dBA, Argentina at 124 dBA).
Some nations limit maximum noise levels to enhance concentration and prevent stress during mental tasks (Cuba, Ecuador, Panama, and Venezuela).
There is relatively little written information about the degree to which these standards and regulations are enforced. Most nations state occupational noise legislation as mandatory, but individual nations vary widely in their ability and inclination to enforce. Even within the same nation, such as the US, enforcement of regulations may vary considerably among jurisdictions and particularly with the administration in power. , Unfortunately, employers in developing nations often disregard noise regulations.
| Conclusions|| |
Legislation regarding occupational noise in the Americas is very diverse, where each country possesses different levels of development and complexity. Some regulations include all the required aspects in occupational noise control, while others only offer minimal protection. However, it is alarming that 27% of the countries in the region still have not established regulations with respect to permissible noise levels and exchange rates. This leaves millions of workers in the Americas unprotected against occupational noise.
Unfortunately, consensus criteria, such as those for community noise, which can aid countries in establishing legislation, are lacking for occupational noise. This would be particularly useful for nations that cannot carry out large epidemiological studies due to social and economic factors.
In the meantime, workers continue to lose their hearing due to the insufficiency of current legislation and enforcement, combined with either a lack of information or a lack of will (or a combination of the two) on the part of employers, employees, and governmental agencies. An important first step in addressing these problems would be to unify the action level and PEL at 85 dBA and adopt a 3-dB exchange rate for calculating noise dose as a function of exposure time and level. These values are currently used by 32% of the nations in the Americas. The history, rationale, and scientific support for each of these recommendations have been widely reported in the literature ,, and they have been adopted in much of the industrialized nations of the world over several decades.
It is important to note that the US OSHA regulation is one of the few in the world that uses a PEL of 90 dBA and the 5-dB exchange rate.  These are factors that bear on the prevalence of noise-induced hearing loss, making the US current occupational regulations unjustifiable and increasingly unconscionable. The result is unfortunate, given that the legislation in the USA is commonly considered as a reference for other countries, particularly those in the course of development. However, in the past, modification proposals for the OSHA regulation have attracted numerous objections from major business associations claiming that these recommendations would have adverse effects on jobs and the economy. 
Another important step in reducing the prevalence of noise-induced hearing loss would be the inclusion of mandatory engineering controls in the legislation of each country. Workers are not sufficiently protected with hearing protectors and other elements of the hearing conservation programs. Workers often fail to wear their hearing protectors or they use them improperly and these hearing protectors can also have adverse effects on communication and the perception of warning signals. Moreover, engineering controls can actually be less expensive in many situations because they are a one-time rather than annual expense.
In every case, the implementation of adequate legislation of occupational noise control will always be limited by the degree of economic development in the countries where they are applied. In many cases, small and medium-sized industries cannot comply with the legislation, making it practically inapplicable. However, the economic costs to society for loss of hearing in workers and the effective disability life-years lost to noise-induced hearing loss can actually result in higher costs than the implementation of adequate legislation. 
In addition, it is recommended that the employee occupational history include summaries of chemical exposures as well as noise exposures. Recent studies have suggested that certain industrial chemicals may potentiate the effect of noise exposure. , The information presented in this paper was intended to provide guidance only and should not be used for other purposes. Most of the information is current as of submission date of this paper, but some standards may have been recently revised. Therefore, anyone doing business in a foreign country is advised to consult the newest versions of the individual nations' standards and existing enforcement policies.
| Acknowledgments|| |
The authors would like to thank several colleagues for their contribution to the information on standards including Juan Aguilar, Luis Bravo, Fernando Elizondo, Samir Gerges, Elizabeth Gonzalez, Jose Herrera, Pablo Kogan, Jorge Moreno, and Sebastian Rolon.
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Dr. Jorge P Arenas
Institute of Acoustics, University Austral of Chile, P. O. Box 567, Valdivia
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]
[Table 1], [Table 2]