In the present study, we evaluated annoyance and the effects of noise on the health of bus drivers. For that, 200 bus drivers from a public transport company participated in a cross-sectional study. Annoyance and effects on health was measured with analog scale: Sleep quality, occurrence of tinnitus, headache, irritation, and annoyance from bus engine, traffic, and passengers. Data of age and working time of bus drivers also were obtained. For noise exposure, LA eq was evaluated in 80 buses. Statistical analysis consisted of mean, standard deviation, minimum, and maximum, Kruskal-Wallis test with post-hoc Dunn, one-way ANOVA with post-hoc Tukey and Spearman's correlation coefficient. Results indicate three groups of bus drivers (not annoyed: (N.A.), a little annoyed (L.A.) and highly annoyed (H.A.)). The group H.A. was younger and with less working time in relation to others, with a significant difference only for age. Regarding sleep quality, there was no significant difference. For results on the occurrence of tinnitus, headache and irritation after work, group H.A. had significantly higher means. Result of annoyance to the bus engine was significantly higher in H.A. than in L.A. and N.A. Annoyance to traffic and passengers, no significant differences were found, but the highest results were found for L.A., followed by H.A. and N.A. Equivalent sound pressure level in buses was above of the limit for occupational comfort. It was concluded that bus drivers has considerable level of noise annoyance and some health effects are perceived. The noise is a factor discomfort ergonomic that may cause effects on health of bus drivers. This study aims to evaluate annoyance and the effects of noise on the health of bus drivers. Cross-sectional study with buses and bus drivers. For that, 200 bus drivers from a public transport company participated in a cross-sectional study. Annoyance and effects on health was measured with analog scale: Sleep quality, occurrence of tinnitus, headache, irritation and annoyance from bus engine, traffic, and passengers. Data of age and working time of bus drivers also were obtained. For noise exposure, LA eq was evaluated in 80 buses. Statistical analysis consisted of mean, standard deviation, minimum and maximum, Kruskal-Wallis test with post-hoc Dunn, one-way ANOVA with post-hoc Tukey and Spearman's correlation coefficient. Results indicate three groups of bus drivers (N.A., a L.A. and H.A.). The group H.A. was younger and with less working time in relation to others, with a significant difference only for age. Regarding sleep quality, there was no significant difference. For results on the occurrence of tinnitus, headache and irritation after work, group H.A. had significantly higher means. Result of annoyance to the bus engine was significantly higher in H.A. than in L.A. and N.A. Annoyance to traffic and passengers, no significant differences were found, but the highest results were found for L.A., followed by H.A. and N.A. Equivalent sound pressure level in buses was above of the limit for occupational comfort. It was concluded that bus drivers has considerable level of noise annoyance and some health effects are perceived.
Keywords: Bus drivers, occupational noise, urban buses
|How to cite this article:|
Bruno PS, Marcos QR, Amanda C, Paulo ZH. Annoyance evaluation and the effect of noise on the health of bus drivers
. Noise Health 2013;15:301-6
| Introduction|| |
Urban bus transportation is an essential service for today's society.  Although there is growth and technological advancement in this type of transportation, all responsibility for the conduction of the bus is on the driver. Thus, this profession plays an important and indispensable role in our industrialized society. However, it appears that these professionals are exposed to a series of ergonomic factors that may negatively affect their health such as high levels of noise, vibration, air pollution, stress, and postural overloads. ,,,
There are several studies on work conditions and health problems among drivers of different types of buses.  However, few studies have evaluated the sensitivity to noise in the driver's work environment.  Initial studies have shown measurements of the level of noise exposure inside buses; however, they have not evaluated the level of annoyance caused by noise or health impacts in bus drivers. ,,,
Due to the many working hours with an average of 8 h/day, driving old buses (with possible mechanical malfunctions and position of the engine near the driver), roads and streets with poor paving conditions and large passenger flow, the noise emitted by buses can exceed the limits for occupational health.  This daily and prolonged exposure to high noise levels can promote negative health outcomes such as reduced hearing threshold and even permanent hearing loss. Other non-auditory effects may occur such as digestive disorders, changes in sleep quality, behavioral disorders, cardiovascular complications, among others. , Confirming the danger of prolonged exposure to noise, the World Health Organization recognizes noise as a risk factor for blood hypertension. ,
These health effects can cause changes in the driver's behavior, irritation, mental fatigue, frustration, and stress. Thus, noise causes damages to the work performance and may be the cause of increases in time off from work, increased social conflicts between drivers and fellow professionals or between drivers and passengers.  The Brazilian legislation (Regulation act NR-15: Insalubrious Operations)  shows a maximal threshold of 85 dB (A) for the 8-h workday. However, NR-17 standard (Regulation act NR-17: Ergonomics)  establishes that a level of exposure exceeding 65 dB (A) during 8 h of work is considerable uncomfortable.
Therefore, assessing the sensitivity to noise and the health effects on bus drivers becomes relevant for the decision making in order to improve the work environment of these individuals. Thus, this study aims to assess the level of annoyance caused by noise from buses and to investigate whether there is an association between annoyance caused by noise and health effects in urban bus drivers. It is assumed that there is a high prevalence of annoyance caused by noise in drivers, and those who reported higher levels of annoyance have a higher prevalence of negative health effects.
| Methods|| |
The aim of the present study was to evaluate the sensation of noise annoyance and its relation to some health parameters in bus drivers from the city of Curitiba, state of Paranα, Brazil. This Brazilian city has received several awards in recent years due to the development of its public transportation system; encouraging checking the work conditions that bus drivers experience in their profession.
For the performance of this study, a purposive sample of 200 drivers from a total of 357 was assessed, who work in a local public transport company. Drivers drove mainly four types of vehicles: Conventional buses-vehicles with front engine, direct buses called "ligeirinhos"- vehicles with rear engine, micro-buses-vehicles with front engine and articulated buses-vehicles with mostly front engine, but recently there are models with rear engine.
For measuring the driver's subjective sensation in relation to annoyance and effects on health, a questionnaire that measured the intensity by means of an analog scale, was developed by authors. The scale has a continuous 10-cm straight line between two antagonistic expressions, e.g., "nothing" and "very." For quantifying the result, the subject is instructed to mark on the scale his sensation level in relation to different questions.
Initially at the beginning of the workday, identification data such as age and time working of the bus driver were collected. Soon after, the analog scale developed was utilized as reference for measuring the sensation intensity to the following questions: What is your sensation regarding the bus noise? ["not annoyed (N.A.)" and "highly annoyed (H.A.)"]; what is your sensation about the quality of your sleep? ("poor" and "excellent"); after the working day, do you fell tinnitus? ("never" and "always"), after the working day, do you get irritated? ("never" and "always"), after the working day, do you have a headache? ("never" and "always") in relation to the engine noise, do you feel uncomfortable? ("never" and "always") in relation to traffic noise, do you feel uncomfortable? ("never" and "always") in relation to noise from passengers, do you feel uncomfortable? ("never" and "always"). Before application of the questionnaire with scales, the whole procedure of filling of questionnaires was explained to the entire sample.
After the questionnaire application, the scales were converted into indexes, which were designed to quantify the driver's sensation regarding the questions. The indexes ranged from 0 to 10, and those closest to zero were the most negative and those closest to 10 were the more positive. The questionnaire reliability was confirmed by Cronbach's alpha coefficient, for the 7 questions with the analog scale (0.758).
For classifying drivers in different levels of noise annoyance was utilized the response of the first question with analogue scale "what is your sensation regarding the bus noise." Thus, drivers was divided into three categories: Drivers who reported annoyance from 0 to 1 were classified as N.A., drivers who reported annoyance from 1.1 to 4.9 were classified with a little annoyed (L.A.) and drivers who reported annoyance above 5.0 were classified as H.A.
Noise levels in 80 buses were equally sampled in four separate sub-samples:  20 conventional buses,  20 speedy buses,  20 micro-buses and, (4) 20 articulated buses. Measurements were performed according to ISO 9612:2009,  carried out in several lines under normal operating conditions. The microphone of the sound level meter was placed at 0.10 ± 0.01 m from the external ear of the bus driver. The ear assessed for incoming noise was that receiving the higher value of the equivalent continuous A-weighted sound pressure level L eq,T in dB (A). Noise exposure level was normalized to a nominal 8-h working day L EX,8 h calculated from the measured equivalent sound pressure level L eq,T. Normalized exposure levels were calculated with the software Protector 7825: 
L EX,8 h = L eq,Te + Log (T e/T 0) in dB (A)
where L eqTe is the equivalent continuous A-weighted sound pressure level, T e the effective duration of a working day and T 0 the reference duration of the working day (8 h). In Curitiba bus drivers work for a period of 6 h/day, with a brief 10-15 min pause after 3 h of driving. Therefore, T e = 6 h in the formula above. Measurements were carried out using the Bruel and Kjaer Mediator 2238 type/class 1 (precision ± 0.41 dB (A))., set for fast response mode, using the A weighing curve. 
Data were analyzed with the use of descriptive statistics as means, standard deviation, minimum and maximum values. For check the normality of data, the Kolmogorov-Smirnov test was used. Data analysis was performed with non-parametric Kruskal-Wallis test and Dunn test for multiple comparisons and parametric one-way ANOVA with Tukey test for multiple comparisons. Spearman's rank coefficient was used to correlate variables. All statistical analyses were conducted in SPSS software version 20, adopting the significance level of P < 0.05.
| Results|| |
The questionnaire was applied to a purposive sample of 200 subjects from a total of 357; thus, obtaining a percentage of 56% from all employees who worked as drivers in the company. All drivers were informed of how the scale should be used and no subject had difficulty in filling it.
In relation to the level of annoyance produced by the bus noise, the sample of drivers was divided into three categories: Drivers who reported annoyance from 0 to 1 were classified as N.A., drivers who reported annoyance from 1.1 to 4.9 were classified with a L.A. and drivers who reported annoyance above 5.0 were classified as H.A.
Of the total sample of 200 drivers, 104 (52%) were classified as N.A., 39 (19.5%) as L.A. and 57 (28.5%) as H.A. [Table 1] shows the results of the descriptive statistics of sample identification data and inferential statistics comparing the three groups of drivers according to age and working time. The results of responses regarding sleep quality, occurrence of tinnitus, headache, irritation, discomfort caused by bus engine, traffic and passengers are also shown.
|Table 1: Descriptive statistics (mean, standard deviation, minimum, and maximum) of the questionnaire and Kruskall Wallis test to compare N.A., L.A. and H.A.|
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The results show that bus drivers classified as (L.A.) were younger than those classified as (H.A.), and those classified as (N.A.) were older. However, only there were significant differences between N.A. and L.A., (P < 0.05). For the working time and sleep quality, no significant difference was observed between groups (P > 0.05).
Regarding questions about the occurrence of tinnitus, low hearing level, headache and irritation after work shift, group H.A. had higher results than groups L.A. and N.A., being significantly different (H.A. > N.A, L.A. > N.A., P < 0.05). For the question on the amount of annoyance produced by the bus engine H.A. was significantly higher than L.A. and N.A. For the annoyance of traffic noise and passengers, H.A. was significantly different than L.A. and N.A. However, L.A. was higher than H.A., but not statistical significantly (P > 0.05).
The following table provides the relationship between the variables (age, working time, sleep quality, occurrence of tinnitus, occurrence of headache, occurrence of irritation, and noise annoyance produced by the bus, [Table 2].
|Table 2: Correlation coefficient for relation among annoyance caused by the bus noise, age, working time and health effects|
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The results demonstrated a significant difference among bus types ( L EX,8h dB (A)), P < 0.05. Measurements indicated that conventional, micro-and articulated buses produce higher noise levels than speedy buses, [Table 3].
|Table 3: Descriptive statistics (mean, standard deviation, minimum, and maximum) of the LEX,8h dB (A) in buses and one-way ANOVA to compare conventional, speedy, micro, and articulated|
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| Discussion|| |
The assessment of annoyance caused by noise was performed subjectively by means of questionnaires with different scales aimed at quantifying the sensitivity of the exposed subject. The sensation in relation to noise is related to the individual personality of each subject, which can affect his reaction toward a noise source.  According to the results of psychoacoustic studies, the sensitivity to noise has no relationship to hearing acuity, but reflects a predisposition, an evaluative judgment for the perception of noise sources.  However, other studies have related subjects with noise annoyance with greater perception of the effects on their health, and objective evaluations showing a decreased quality of health in individuals with high exposure to noise. 
Annoyance questions in different studies do not use the same number of response categories. Some questions have only 3 response categories, whereas others use as many as 11 categories. Often a cutoff point is chosen on the scale, and the percentage of the responses exceeding the cutoff is reported. Miedema and Oudshoorn  proposes the cutoff with 72 on a 0-100 scale, then the result is called the percentage of H.A. persons; with a cutoff at 50 it is the percentage "annoyed", and with a cutoff at 28 it is the percentage "(at least) a L.A." In our study, it is proposed an alternative scale (0-10) and different cutoffs (0-1: N.A., 1, 1-4,9: A L.A. and >5 with H.A.). The alternative scale and different cutoffs facilitates the assessment of subjects with low educational level (bus drivers), with the reduction in the number of classifications in relation to the noise annoyance.
According to the results obtained, group L.A. was the one with the lowest average age, followed by groups H.A. and N.A. Heinonen Guzejev  assessed the sensitivity to noise in a sample of individuals and found similar results, where younger subjects had higher levels of sensitivity to noise compared to older subjects. Sandrock et al.  point to an adaptation of the auditory system of individuals exposed to environments with high noise levels for several years, reducing their sensitivity and thus, perhaps disguising their effects on the subject.
The results for the three groups showed no significant differences in relation to the working time. However, there was a decreasing relationship between working time and noise annoyance; drivers exercising their function for a longer time reported lower levels of annoyance (N.A. 9.36 years; L.A. 7.72 years; H.A. 7.63 years). Thus, it is noteworthy that there is a possible inverse relationship between higher annoyance and lower age or working time among drivers in this study (age x annoyance caused by the bus noise: 0.617, working time x annoyance caused by the bus noise: 0.576, verified by Spearman's correlation).
In assessing the relationship between noise annoyance and sleep quality, no significant difference was found; however, the result remained decreasing for the three groups, and group that had no noise annoyance showed the highest sleep quality, compared to the group with much noise annoyance (N.A. 9.36, H.A. 7.65). Several authors have reported that continuous exposure to noise can cause sleep-related disorders. , Thus, measures of association between loss of sleep quality and noise exposure are important indicators of quality of life of workers, since sleep is an essential factor for job performance. 
For the evaluation of the occurrence of tinnitus, headache and irritation after the working day, significant difference was found for the three groups, and group H.A. was the one that had the highest indexes, followed by groups L.A. and N.A. Thus, it appears that the group with the highest noise annoyance has greater sensitivity to these factors.
One of the major health consequences resulting from exposure to noise in bus drivers is related to the occurrence of hearing disorders.  These effects on the health of bus drivers are worrisome, since they influence not only the work environment, but also their quality of life as a whole. Hearing loss, irritation and continuous episodes of headache contribute for the profession of the bus driver to become one with the highest stress load;  thus, leading these workers to have harmful consequences to their health such as cardiovascular diseases, among others. , These health effects cause trouble also for transport companies, because drivers with high stress load and hearing loss tend to show lower performance in their jobs and more time off from work. ,
The results of the evaluation of noise annoyance produced by the bus engine indicate a strong influence of this factor on the sensibility of drivers; group H.A. with 6.06 against 2.87 of group L.A. and 0.89 of group N.A. Thus, it could be inferred that the noise from the engine heard inside the bus, especially when close to the driver, is a major cause of discomfort and consequent increase in the level noise experienced by bus drivers. Previous studies have contributed to the understanding of noise exposure inside buses and the results show a slightly significant difference for vehicles with front engine. ,, Thus, vehicles with rear engine provide lower noise emission and thus reducing the driver's sensibility to this factor.
The last two factors evaluated: Level of annoyance due to traffic and passenger noise can collaborates to turn the work environment uncomfortable and can influence drivers' health. Studies on passenger traffic noise have also shown that these factors may increase the emission of noise inside the vehicle and consequently felt by the driver. , Traffic with large amounts of heavy vehicles and a large amount of passenger flow increase the noise level within the bus environment, and these factors are exacerbated during peak hours of traffic and passengers.
Findings of this study are similar to those of earlier studies carried out in Curitiba, Brazil with conventional and speedy buses during their entire route and noise levels normalized to 8 h, L EX,8h. Zannin  found that noise equivalent level were emitted by conventional buses (79.9 ± 2.8 dB (A)) and by speedy buses (73.0 ± 2.6 dB (A)), and in the study of Zannin et al.,  L EX,8h results were in conventional bases (79.9 ± 3.1 dB (A)) and in speedy buses (72.7 ± 2.4 dB (A)). Results of the present study were considered normal when compared to Brazilian legislation (Regulation Act NR-15: Insalubrious Operations).  Values recorded were at a threshold below 85 dB (A) of exposure in a daily 8-h workday. However, NR-17  standard (Regulation Act 17: Ergonomics) establishes that a level of exposure exceeding 65 dB (A) during 8 h of work is considered uncomfortable. Therefore, current values recorded should not be considered optimal for health and should be reduced in order to improve the work environment of bus drivers subjected to such noise levels.
| Conclusions|| |
The results of this study show that the sample of bus drivers has factors that should be considered in the attempt to reduce the annoyance produced by the engine noise and consequent health problems. It was found that the sensation of discomfort was more apparent in younger drivers than in older ones and with longer working time.
Among groups N.A., a L.A. and H.A., there was a greater intensity for tinnitus, headache and irritation for group H.A. Thus, the group with the highest uncomfortable sensation seems to be the one with more health problems from exposure to noise.
For noise levels from engine, traffic and passengers, the results indicate that the vehicle engine is the major source of discomfort, followed by the noise from traffic and finally from passengers. The measured noise on the bus indicates that the vehicles are in accordance with Brazilian standard occupational; however, appears above the comfort limits for work. Organizational changes in the workplace and use of vehicles with rear engine can contribute to a better working environment for these professionals.
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Portela S Bruno
Rua Simeao Camargo Varela de Sa, 03, Cx. Postal 3010, CEP 85040-080, Guarapuava, PR
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]