Urban Noise Pollution: A Growing Threat to Health and Environment
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, as cities become more crowded, their soundscapes become a global public health menace. Noise pollution is not a mere inconvenience, but a serious health and environmental issue. Nor is it an unavoidable part of urban life.
Since 1972, the World Health Organization (WHO) has declared noise as a pollutant. Acceptable noise levels, as defined by the World Health Organization, are now surpassed in cities across the world. 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.
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.
Sources of Urban Noise
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.
Urban noise can be considered one of the main sources of 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.
The Impact of Noise Pollution
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. Noise pollution is not a mere inconvenience, but a serious health and environmental issue.
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.
Research makes clear that natural sounds, emanating from green urban spaces, can offer various health benefits. 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.
Case Study: Noise Exposure in Porto, Portugal
A 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. 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.
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.
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.
Selected Zones (1 to 6) in the Porto city, Portugal, 2012. Source: Google Maps
Methodology
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.
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.
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.
Findings
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).
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.
Figures 2-6 show the noise maps of each urban soundscape, from which it was possible to validate the exposure areas.
Exposure areas and energetic average in urban soundscapes (leisure, work and home):
| Scenario | Exposed Area | Energetic Average (dB) |
|---|---|---|
| Leisure | Quinta do Covelo | Exceeded legal limits |
| Work | 31 de Janeiro St., Passos Manuel St., and Sá da Bandeira St. | Exceeded legal limits |
| Home | Outeiro neighborhood | Exceeded legal limits |
| Leisure | Parque da Cidade | Below legal limits |
| Work | Santa Catarina St. | Below legal limits |
| Home | Carriçal neighborhood | Below legal limits |
Mitigating Urban Noise Pollution
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.
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.
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.
In 2002, the European Union adopted the Directive 2002/49/CE 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.