The Detrimental Effects of Urban Noise Pollution
Cities provide something for everybody: opportunities for employment and entertainment; diversity and density, social benefits as well as social tensions. As most of the world urbanises, cities are becoming an increasingly important ecosystem, not just for humans, but for biodiversity as a whole. However, research makes clear that natural sounds, emanating from green urban spaces, can offer various health benefits.
In her book, The Death and Life of Great American Cities, Jane Jacobs wrote that cities can provide something for everybody only because, and only when, they are created by everybody. That elusive egalitarian ideal is rarely realised today. City planners should take both the health and environmental risks of noise pollution into account. Yet much more is needed to tackle the din in much of the world’s cities. Noise pollution is not a mere inconvenience, but a serious health and environmental issue. Nor is it an unavoidable part of urban life.
Understanding Urban Noise Pollution
Urban noise can be considered one of the main sources of pollution. Nowadays, acoustical environmental quality in urban areas is threatened. The urban environment is composed of several audible sources: Traffic (road, rail, and air), industrial facilities, civil construction and social activities (parties, fairs and open air markets, and residential noise). These all contribute to the conversion of the soundscape in noise pollution.
Noise pollution can be considered one of the main agents of loss of environmental and life quality in a metropolis and its dissemination pushed the boundaries of industrial facilities, spreading through the streets and also for leisure activities, moments of rest and work. Schafer introduced the concept of soundscape as a scope to thinking beyond the noise levels, considering human experience in the environment and its cultural dimension. Soundscape research means to focus on the meaning of sounds and its implicit assessments, and understanding perceptual effects.
Defining Noise Pollution
Much like air pollution, noise pollution is far from being a mere nuisance. In fact it is increasingly understood to have long-term effects on human health. Defined as unwanted, prolonged and high-level sounds, it can seriously impair our physical wellbeing. As cities become more crowded, their soundscapes become a global public health menace. Acceptable noise levels, as defined by the World Health Organization, are now surpassed in cities across the world.
Examples of Noise Pollution in Cities
- An estimated 90 per cent of New York City mass transit users are exposed to levels exceeding the recommended decibel limit.
- In Ho Chi Minh City, cyclists are exposed to noise levels above 78dB, which can cause irreversible hearing loss.
The Legal and Regulatory Landscape
In recent years, there has been a great mobilisation of resources to combat air pollution, which is responsible for the premature death of more than 7mn people a year. Cities need a similar campaign waged against the cacophony that is harming people and planet. The 1990 Clean Air Act Amendments added a new title IV, relating to acid deposition control, without repealing the existing title IV, relating to noise pollution. Code Collection maintained by the U. S. Government Publishing Office.
The traditional definition of noise is “unwanted or disturbing sound”. Noise and Its Effects, by Dr. Alice H. Under the Clean Air Act, the EPA administrator established the Office of Noise Abatement and Control (ONAC) to carry out investigations and studies on noise and its effect on the public health and welfare. Through ONAC, the EPA coordinated all Federal noise control activities, but in 1981 the Administration concluded that noise issues were best handled at the State and local level. As a result, ONAC was closed and primary responsibility of addressing noise issues was transferred to State and local governments.
Since 1972, the World Health Organization (WHO) has declared noise as a pollutant. In 2002, the European Union adopted the Directive 2002/49/CE20[8] regarding the assessment and management of environmental noise, with the goal of controlling and reducing sound pollution using a common approach and avoiding or preventing the harmful effects of noise exposure. The EU established the enforcement of developing strategic noise maps that should estimate the exposure to outside ambient noise, based on assessment methods in agreement to the EU levels.
Study on the Effects of Noise Exposure
Over the last decades, the quality of the urban environment has attracted the interest of researchers due to the growing urban sprawl, especially in developing countries. The objective of this study was to evaluate the effects of noise exposure in six urban soundscapes: Areas with high and low levels of noise in scenarios of leisure, work, and home.
Methodology
Cross-sectional study. The study was conducted in two steps: Evaluation of noise levels, with the development of noise maps, and health related inquiries. 180 individuals were interviewed, being 60 in each scenario, divided into 30 exposed to high level of noise and 30 to low level. Chi-Square test and Ordered Logistic Regression Model (P < 0,005).
Findings
- 70% of the interviewees reported noticing some source of noise in the selected scenarios and it was observed an association between exposure and perception of some source of noise (P < 0.001).
- 41.7% of the interviewees reported some degree of annoyance, being that this was associated with exposure (P < 0.001).
- There was also an association between exposure in different scenarios and reports of poor quality of sleep (P < 0.001).
- In the scenarios of work and home, the chance of reporting annoyance increased when compared with the scenario of leisure.
Study Area: Porto, Portugal
This paper presents an evaluation of soundscape, bearing in mind that sensations and perceptions may differ depending on the activity performed, even considering individual and subjective questions. Thus, we selected three different daily activities: Leisure, work, and rest, under the influence of noise sources. The study was conducted in the city of Porto, which is the second-largest city of Portugal, with an area of 41.66 km2 and a population of 237,000 inhabitants.
Selected Zones (1 to 6) in the Porto city, Portugal, 2012. Source: Google Maps
Two areas representative of the exposure categories were selected within each scenario. Areas influenced by traffic noise were chosen to represent the exposed areas and areas with little influence from traffic noise were selected for the non-exposed areas. Noise maps are descriptors of external environmental noise, expressed by means of indicators, which are determined by reference periods and represented by lines that indicate the identical rating levels (isophone lines) and limit the areas to which a specific class of values expressed in decibels (dB[A]) corresponds.
The development of the noise maps was based on the allocation classification criteria for each area. Areas that are allocated for residential use, as well as schools, hospitals, and public leisure areas were classified as sensitive zones. For the scenarios of leisure and work, the noise maps were based on the Lden indicator and for the home scenario the indicator used was Ln. The development of the noise maps was divided in three steps: Preparation, modeling, and calibration.
During preparation, the selected areas were approached with fieldwork for the identification of noise sources, measurements, and counting. The calibration involved the selection of measurement points, which was done with the support of the Noisemeter Bluesolo 01dB Metravib, properly calibrated. All measurements were performed using the response time weighting S (slow) to allow better reproducibility, respecting weather conditions, and following the rules regarding the placement of 1.20 m relative to the ground, using the tripod and at least 3.5 m from any reflective screen, including walls and façades.
Specific Locations and Their Noise Levels
The noise maps are representative of the acoustic situation in a determined region during the period of 24 h. To calculate the energetic average in the leisure scenario, a route with a higher probability of being used by the urban park-goers was designed. This route was based on walking paths, areas to rest and to practice physical activity. Outside this route there were areas with dense vegetation. The exposure levels were calculated for this route.
In the work scenario, specific points at the façades of commercial buildings were selected in the streets and in the home scenario the points were at the façade of the selected buildings. Quinta do Covelo is a green area of about eight hectares located amidst a residential area in the ancient parish of Paranhos and its boundaries are four streets: Faria Guimarães St., Bolama St., Monte de São João St., and Álvaro de Castelões St. The park is also very close to the exit of Via de Cintura Interna (VCI). The VCI is a 21 km long highway of fast circulation, which supports an average daily traffic of 21,000 vehicles and surrounds the central area of Porto.
The Parque da Cidade, located in the parish of Nevogilde is the largest urban park in Portugal, with an extension of 83 green area hectares and a long network of pathways (around 10 km). The selected streets were located in Baixa do Porto, which comprises the central area of the city, where the largest commercial streets are. The exposed streets were: 31 de Janeiro St., Passos Manuel St., and Sá da Bandeira St., for they are located near sources of urban traffic: Both highways and railways [Zone 3 - Figure 1]. The non-exposed street was located in a zone that allows only pedestrian traffic, Santa Catarina St.
The selected trade stores were those with open doors facing the highways in order to verify the direct impact of noise from this source in attention and concentration activities. The selected residential areas were two low-income housing neighborhoods in the city of Porto. The Outeiro neighborhood, located in the parish of Paranhos is comprised of 13 residential buildings where 418 families live. Five buildings with their façades facing the VCI were selected, each one three-stories tall having two apartments per floor, in a total of eight apartments.
The Carriçal neighborhood, also located in the parish of Paranhos is comprised of 11 residential buildings, each one four-stories tall having two apartments per floor, in a total of ten apartments where 250 families live. For comparison purposes, five buildings located in the internal area of the neighborhood were selected.
Perception and Annoyance Study
A cross-sectional study was conducted from March to May 2012 to evaluate the perception and annoyance in the urban soundscapes: During the leisure time, at home, and at work in different exposures (noise levels). The study population consisted of adult individuals older than 20 years old who agreed to answer a questionnaire. In each scenario, three visits were made.
In the leisure scenario, the interviews were conducted during the week and on the weekends to ensure the representativeness of the sample. In the work scenario, the visits to commercial establishments were made during the slowest hours (right after opening, in the mid-morning, and in the mid-afternoon). In the home scenario, with the support of the Camera do Porto (Porto City Council), the study was announced by the administrators of the selected housing projects so that the field workers could access the households easily.
The sampling process showed peculiarities inherent to the characteristics of the urban soundscapes and the type of study, which aimed at comparing the exposure areas. Therefore, in the leisure scenario the sample was selected randomly and included 60 participants. The sample size was relatively small due to the difficulties in getting collaboration from the park-goers, who were performing physical or leisure activities and were not available for answering the questionnaire.
In commerce, stores with staff of different nationalities such as Chinese and Indian were excluded, due to difficulty with language comprehension. There was a high rate of refusal, mainly in stores that were part of a large network, where there was camera monitoring and the employees claimed not to be allowed to answer any type of survey. Approximately 90 commercial establishments were visited and 60 interviews were made, leading to approximately 30% of loss.
e)Perception regarding the environmental problems and noise pollution in particular. The demographic profile of the population according to the perception of noise sources and environmental problems, as well as the effects of exposure in the urban soundscape was drawn based on the descriptive analysis. To identify associations between exposure and perception of sources and potential effects of this noise exposure in the urban soundscape, the Chi-square test was used.
Figures 2-6 show the noise maps of each urban soundscape, from which it was possible to validate the exposure areas. In Figures 2 and 3, the chosen route for calculating the energetic averages in the urban parks can be observed, followed by the related noise maps.
Urban soundscape - Leisure - Selected route and their noise map in exposed area: Quinta do Covelo.
Urban soundscape - Leisure - Selected route and their noise map in non-exposed area: Parque da Cidade. Porto, Portugal, 2012
The façades of the selected commercial buildings as well as the related noise maps are presented in Figures 4 and 5.
Urban soundscape - Work - Façades of commercial buildings evaluated and their noise map in exposed area, Streets: 31 de janeiro, Sá da Bandeira and Passos Manuel.
Urban soundscape - Work - Façades of commercial buildings evaluated and their noise map in non-exposed area, Santa Catarina Street. Porto, Portugal, 2012
The selected buildings in the home scenario as well as the noise maps in the selected neighbourhoods are presented in Figures 6 and 7.
Urban soundscape - Home - Evaluated buildings in the selected housing project in exposed area: Outeiro neighborhood and their noise map.
Urban soundscape - Home - Evaluated buildings in the selected housing project in non-exposed area: Carriçal neighborhood and their noise map. Porto, Portugal, 2012
The energetic averages calculated in each scenario also allow the inference that the areas chosen to be representative of the exposed areas have exceeded the legal limits while the non-exposed areas had values below these limits.
One hundred and eighty individuals were interviewed, 60 in each of the three defined scenarios. The interviewees’ average age was 52-years-old (IC95%: 49.54-54.49). Demographic characteristics, perception of noise sources, annoyance and other effects caused by exposure to noise, and perception of environmental problems according to the interviewees in each urban soundscape (leisure, work and home).
| Characteristic | Leisure | Work | Home |
|---|---|---|---|
| Average Age | 52 (sd=16.3) | 51 (sd=12.9) | 53 (sd=17.5) |
| Perception of Noise Sources | 65% | 85% | 60% |
| Annoyance Caused by Noise | 20% | 48.3% | 48.3% |
| Consider Noise an Environmental Problem | 88% | 90% | 86% |
| Believe Noise Exposure Aggravates Health | 84% | 82% | 86% |
Demographic characteristics, perception of noise sources, annoyance and other effects caused by exposure to noise, and perception of environmental problems according to the interviewees in each urban soundscape (leisure, work and home).
- UN = Unknown
- sd = Standard deviation
Key Findings from the Study
They considered their hearing to be good (75.6%), although 62% had never been subjected to a hearing exam. Considering the perception of noise sources in the different urban soundscapes, including noise by highway, railway, and air transport and neighborhood noise, 70% of the individuals reported noticing some source of noise in the selected scenarios.
With regard to the annoyance caused by the urban noise in all urban soundscapes, 41.7% mentioned feeling some degree of annoyance and, among them, 16.7% felt highly annoyed. The majority of the interviewees considered noise as an environmental problem (88%) and believed that noise exposure can cause or aggravate health conditions [84%, Table 2]. The majority (91.7%) of individuals mentioned attending the parks for recreation, although the park has many facilities focused on physical activity.
The majority of interviewees (65%) also mentioned noticing noise sources within the parks, being 31.7% relative to the highway noise and 23.3% the aircraft noise. Despite this perception, 65% reported considering the park environment quiet and 20% reported little annoyance [Table 2]. 85% of the interviewees reported noticing noise sources in the workplace and, among them, 50% reported railway noise, followed by noise by liberal professionals, as is the case of musicians (25%).
When questioned about the quality of sound in the work environment, 53.3% considered the environment noisy, among them, 20% found it extremely noisy. The presence of chronic illnesses was referred by 28.3% of interviewees. Concerning the annoyance caused by noise, 48.3% of traders reported some degree of annoyance caused by the perceived noise, being that 11.7% reported to be highly annoyed by noise.
Among the interviewees, 78.3% have lived for over six years in the selected neighbourhoods. Regarding their perception of noise sources inside their homes, 60% referred noticing noise sources and 48.3% of these were related to the highway noise. The perception that noise levels became elevated during night-time was reported by 43.3%. The majority (53.3%) considered the home as a silent location.
Statistical Analysis
An ordinal logistic regression was performed to identify factors associated with annoyance, adjusted by the following variables: Gender, age, and education. It was observed that in the work scenario the chance of reporting significant annoyance was tripled when compared with the leisure scenario (OR: 3.51; IC95%: 1.31-9.39), while in the home scenario, this chance was the quadruple of that of the leisure scenario (OR: 8.40; IC95%: 3.04-23.19).
The effects of exposure to noise on the human organism are subject to the specific characteristics of the noise, such as frequency, intensity, and exposure time, and also individual susceptibility.
Multivariate ordered logistic regression model for the annoyance regarding noise.
- US = Urban soundscapes
- *Adjusted for...
Mitigation Strategies
In some cases, vegetation in urban environments can absorb acoustic energy and diffuse noise. Tree belts, shrubs, green walls and green roofs not only help amplify natural sounds by attracting wildlife, but improve the visual streetscape as well.