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Year : 2004  |  Volume : 6  |  Issue : 24  |  Page : 43--49

Road traffic noise and annoyance-an increasing environmental health problem

G Bluhm1, E Nordling2, N Berglind1,  
1 Department of Occupational and Environmental Health, Stockholm County Council; Institute of Environmental Medicine, Karolinska Institute, Sweden
2 Department of Occupational and Environmental Health, Stockholm County Council, Sweden

Correspondence Address:
G Bluhm
Department of Environmental Health, Norrbacka, 3rd floor, Karolinska Hospital, SE-171 79 Stockholm
Sweden

Abstract

Traffic noise, which is steadily increasing, is considered to be an important environmental health problem. The aim of this study was to estimate the degree of annoyance and sleep disturbance related to road traffic noise in residential settings in an urban community. The study is based on a questionnaire on environmentally related health effects distributed to a stratified random sample of 1000 individuals, 19-80 years old, in a municipality with heavy traffic in the county of Stockholm. The response rate was 76%. The individual noise exposure was estimated using evaluated noise dispersion models and local noise assessments. Frequent annoyance was reported by 13% of subjects exposed to Leq 24 hr >50 dBA compared to 2% among those exposed to <50 dBA, resulting in a difference of 11% (95% Confidence Interval (CI) 7%, 15%). Sometimes or frequently occurring sleep disturbance was reported by 23% at Leq 24 hr >50 dBA and by 13% at levels <50 dBA, a difference of 11% (95% CI 4%, 18%). A positive exposure- response relation was indicated for annoyance as well as for sleep disturbances when classifying the individuals into four different exposure categories (< 45, 46­ 50, 51-55 and >55 dBA Leq 24 hr). There was some habituation to noise for problems related to sleep but not for annoyance. The prevalence of both annoyance and sleep problems was higher when bedroom windows were facing streets. People living in apartments had more sleep problems compared to people living in detached or semi-detached houses. In conclusion traffic noise exposure, even at low levels, was associated with annoyance and sleep disturbance. Access to a quiet side seemed to be a major protective factor for noise related problems.



How to cite this article:
Bluhm G, Nordling E, Berglind N. Road traffic noise and annoyance-an increasing environmental health problem.Noise Health 2004;6:43-49


How to cite this URL:
Bluhm G, Nordling E, Berglind N. Road traffic noise and annoyance-an increasing environmental health problem. Noise Health [serial online] 2004 [cited 2020 Oct 22 ];6:43-49
Available from: https://www.noiseandhealth.org/text.asp?2004/6/24/43/31656


Full Text

 Introduction



Traffic noise is an increasing problem in the modern society and it is the dominating source of noise in the urban environment (Ouis, 1999). In the European Union 40% of the inhabitants are exposed to equivalent noise levels exceeding 55 dBA in daytime and more than 30% in night­time (The National Board of Health and Welfare et al., 2001). In Sweden, almost two million people are exposed to equivalent noise levels exceeding 55 dBA and almost one million are annoyed by noise outside or near their homes once a week or more often (Swedish Environmental Protection Agency and Statistics Sweden, 2000).

Common noise related problems are interference with communication and sleep disturbance (Griefahn et al., 2000). Decreased quality of sleep is considered to be a major health outcome of environmental noise (Berglund and Lindvall, 1995). Noise exposure can also cause other non­auditory effects such as annoyance, changes of behavior and deterioration in performance. Long- term effects of road traffic noise on psychosocial health and wellbeing are also described (Ohrstrom et al., 1998). Studies have shown that people living near streets with busy traffic or airports close their windows, spend less time in their gardens, and have less visitors than people living in more quiet areas (Griefahn, 2000).

Primary physiological effects of noise exposure are vegetative reactions such as increases in blood pressure, heart rate and finger pulse amplitude, cardiac arrhythmia and changes in respiration and body movements (Berglund and Lindvall, 1995). Secondary effects are reduction in perceived sleep quality, increased fatigue, decreased mood or wellbeing and deterioration in performance. Cardiovascular effects of traffic noise such as hypertension and ischaemic heart disease have also been described but epidemiological evidence is still limited in this respect (Babisch, 2000). In a recent study a relationship between aircraft noise exposure and hypertension has been reported (Rosenlund et al., 2001).

The present study was initiated due to increasing amount of complaints on traffic noise from the inhabitants in Sollentuna, a municipality outside Stockholm with heavy traffic from roads as well as from the railway. Our objective was to analyse annoyance and sleep disturbances in relation to road traffic noise in residential settings in the municipality and to investigate at what exposure levels these effects appeared. We also wanted to investigate the influence of factors such as room orientation and satisfaction with residence on the reaction to noise exposure.

 Study population and methods



In April 1997 a postal questionnaire used in a Stockholm County survey of environmental factors and health was distributed to 1000 individuals 19-80 years of age living in Sollentuna municipality north of Stockholm City.

One sample was drawn from buffer zones of 100 meters on each side of main roads, highways and the railway (n=500). Another sample was drawn from the remaining part of the municipality (n=500). As the present study was focused on road traffic noise, subjects living within 100 meters from the railway (n=135) were not included in the analyses. The sampling was performed by Statistics Sweden by combining The National Population Register, containing background information for the study population, with the Central Register for Real Estate Data containing geographical co­ordinates for the individuals residences. After up to three written reminders a total of 657 individuals answered the questionnaire, giving a response rate of 76%.

The individuals were classified into four exposure categories with equivalent road traffic noise levels, Leq 24 hr 55 dBA, according to the location of their residences. For the six-lane highway that intersects the municipality, a Nordic prediction model for road traffic noise was available from the Swedish National Road Administration (Swedish Environmental Protection Agency et al., 1999). The local Environment and Health Protection Administration had applied the same prediction model for other major roads in the area. For residences not covered by any of the models, the noise exposure was determined manually by an environmental health officer with knowledge of the local noise situation.

The questionnaire included 87 questions mainly focusing on prevalence of allergic diseases and environmental risk factors for health of regional importance such as air pollution and noise. General background factors such as sex and age were obtained from the National Population Register, while the questionnaire provided information on education level, employment status, living conditions, residential time, smoking habits, general annoyance and sleep disturbances due to traffic noise. To estimate annoyance and sleep disturbances questions with a scale of four were used: "Yes, often (every week)", "Yes, sometimes", "No, never" and "Not relevant/ no noise". Sleep disturbances were classified as awakenings and/or difficulties falling asleep. Annoyance and sleep problems were defined as frequent when occurring every week.

To compare prevalence of annoyance and sleep disturbances due to road traffic noise at different exposure levels, crude and standardized differences in proportions were calculated. The standardized differences in proportions were calculated using the distribution of exposure in the general population as estimated from the survey as weights for standardization. The standardised differences in proportions are interpreted as the difference between the groups if exposure was identically distributed in the groups. Proportions and differences of proportions are presented along with 95% confidence intervals (95% CI). A chi-square test for linear trend was used to test whether or not there was a linear trend in the proportions of annoyance and sleep disturbances over noise exposure categories.

 Results



Annoyance

Frequent annoyance was reported by 12.8% among individuals exposed to equivalent road traffic noise levels above 50 dBA and by 2.1%for those exposed to lower levels, resulting in a difference of 10.7% (95% CI 6.9%, 14.5%). Corresponding figures for sometimes or frequently occurring annoyance were 38.9% and 13.3% with a difference of 25.6% (95% CI 19.1%, 32.1%). Among those exposed to equivalent noise levels above 55 dBA sometimes or frequently occurring annoyance was reported by 50.0%. When analyzing the four exposure categories (55 dB), a positive trend was found for both "sometimes or frequent" and "frequent" annoyance [Figure 1].

There were no differences regarding reported annoyance due to sex, age, residence time or education [Table 1]. A difference was indicated between single-family houses and apartments, but this was reduced after standardization. Annoyance was reported among 39.6% and 23.3% in the groups with bedroom window facing the street and bedroom window facing the garden, respectively. The difference remained significant after standardization. Annoyance from road traffic noise at 24 hr average exposure levels >50 dBA was reported by 28.0% among those who were satisfied with their residences and by 42.3% among those who were less satisfied. Also this difference was significant after standardization.

Sleep disturbances

Frequently occurring sleep disturbances were reported by 13 persons (3.9%) among those with 24 hr sound pressure levels >50 dBA, and by 2 persons (1.2%) among those exposed to lower levels, giving a difference of 2.7% (95% CI: 0.02%, 5.4%). Corresponding figures for sometimes or frequently occurring sleep disturbances were 23.6% and 12.8% respectively giving a difference of 10.8% (95% CI 3.9%, 17.6%). There was a positive exposure-response trend both for "sometimes or frequent" and "frequent" sleep disturbance [Figure 2].

Regarding problems with sleep there were no differences regarding sex, age and education [Table 2]. People living in single family houses reported sleep disturbances in 16.5% compared to 25.4% among people living in apartments, with a standardised difference of -13.0% (95% CI -21.8%, -4.1%). The prevalence of sleep problems was also significantly lower in the group with residential time >10 years.

In general more people were disturbed among those with their bedroom windows facing the street. In total 27.0% reported sleep disturbances in this group compared to 15.9% among those with their bedroom windows facing a quiet side [Table 2].

 Discussion



Annoyance

In the present study there was a clear relationship between the proportion of individuals reporting annoyance due to road traffic noise and modelled exposure levels. This is in accordance with previous studies (Abel 1990; Stansfeld et al., 1993)

A considerable number of the respondents reported annoyance already in the interval 50-55 dBA. The crude classification of annoyance used in the present study compared to the scale of five that was described by Stansfeld et al. (1993) could, at least partly, explain this. In that study also the equivalent sound level was calculated from 6 am to 10 PM, while 24 hour periods were used in the present study. 24 hr noise levels of road traffic are usually 1 to 3 dBA lower than daytime noise levels (Rylander et al., 1986). A possible misclassification due to underestimation of true noise levels can also not be excluded.

The orientation of the bedroom window was of major importance for the over all prevalence of annoyance due to road traffic noise. In total annoyance was more commonly reported among those with bedroom windows facing the street, but there was a similar trend with increasing annoyance at higher exposure levels in both groups. This is in agreement with previous studies (Ohrstrom, 1993a).

Some studies have indicated that elderly people are more affected by noise (Berglund and Lindvall, 1995). Gender differences have also been discussed (Passchier-Vermeer and Passchier, 2000). However in the present study there were only minor divergences regarding reported annoyance and sleep disturbances related to sex. There were also no obvious age­dependent differences.

It has been suggested that people might get used to noise with longer residential time (Griefahn et al., 2000) A reason for a decrease in number of complaints might be that annoyed people move elsewhere. In other studies an increase in annoyance with longer residential time has instead been described (Abel, 1990). In the present study no difference related to time of residence was observed.

It has previously been reported that people living in single-family houses experience annoyance in a higher degree than those living in apartments do (Abel, 1990). In the present study no such difference was observed when taking into account the distribution of exposure.

Satisfaction with residence was related to a low frequency of reported annoyance. This is in accordance with previous findings (Ohrstr6m, 1993a). Naturally noise exposure could be a reason for dissatisfaction. On the other hand an increased vulnerability for stress inducing factors could trigger annoyance due to noise exposure. It has been proposed that with a belief that noise has an influence on health it is likely that exposure to noise can cause dissatisfaction and annoyance (Job, 1996).

Sleep disturbances

Few people reported frequent sleep disturbances but several were occasionally disturbed. Laboratory studies have indicated that self­ reported noise related problems with sleep could give an underestimation of the physiological effect (Ohrstrom, 1993b). Thus, even if many people only experience sleep disturbances occasionally it may indicate more serious influence on sleep quality.

A limitation of this study is that we only had information about equivalent noise levels. Laboratory studies have indicated that maximum noise levels and the number of events exceeding a certain sound pressure level, are better associated with sleep disturbance (Ohrstrom and Rylander, 1990; Ohrstrom, 1991). However, in this study equivalent noise levels seemed to be well correlated with sleep disturbances and there was an obvious exposure-response relationship.

Noise effects are reported to be dependent on mediating factors like room orientation and window opening habits. Thus it is strongly indicated that such factors should be considered in the analysis of reactions to noise (Ohrstrom, 1993a). If the bedroom window faces the street, the time needed to fall asleep increases (Ouis, 1999). More serious physiological effects have also been described with window orientation towards busy streets (Babisch, 2000). In the present study there was also a higher frequency of self-reported sleep disturbance among those with bedroom window facing the street.

In the future sleep disturbances are expected to increase since traffic density will grow, more during the night than during the day (Griefahn et al., 2000). The orientation of the bedroom is therefore important to take into account when planning for residential areas.

That women can be more sensitive to noise during sleep than men has been suggested previously (Berglund and Lindvall, 1995). However in this study no such difference was observed.

As for annoyance, studies have shown that full habituation do not occur for sleep disturbances (Griefahn et al., 2000). In their investigation a time dependent decrease but no extinction of noise- induced reactions was observed for people living in noisy areas. However in the present study there was a marked decrease for sleep disturbances but not for annoyance with longer residential time.

An unexpected finding was that people living in single family houses had a much lower frequency of sleep problems, a difference that increased after standardization for modelled exposure levels. Possible explanations for this might be differences in coping strategies, or differences in building construction that may affect the actual levels inside the homes.

 Conclusion



In this study many people reported disturbances from road traffic noise already at lower noise levels. There was an obvious exposure-response relation both for annoyance and problems with sleep. Bedroom window orientation seemed to be a factor of main importance for occurrence of disturbances related to traffic noise exposure.[20]

References

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