The loud noise of persistent traffic, factories and construction sites, and the circulation of airplanes can cause damage to health that goes beyond the loss of hearing. The report “Noise, Blazes and Mismatches: Emerging Issues of Environmental Concern,” published in 2022 by the United Nations Environment Program (UNEP), indicates that, in Europe, prolonged exposure to environmental noise tends to contribute to the development of 48,000 new cases of ischemic heart disease per year, leading to 12,000 premature deaths. Noise maps, a tool used to analyze urban acoustics, identify critical points, and support the development of control measures, are still in the early stages of implementation in Brazilian cities. Research by architect Bianca Carla Dantas de Araújo, of the Federal University of Rio Grande do Norte (UFRN), shows that, to date, only four municipalities have completed producing this type of document.
The World Health Organization (WHO) considers noise levels above 65 decibels (dB) as pollution, presenting significant potential to affect human health. Therefore, the PNUMA document warns that the recommended noise levels, that is, 55 dB for outdoor environments in residential areas and 70 dB for traffic and commercial areas, are surpassed in cities in various parts of the world, including Algiers, in Algeria, Bangkok, in Thailand, Damascus, in Syria, and New York, in the USA. Brazil was not included in the analysis. It also highlights that the exposure to abrupt and intense noises, such as a gunshot or fireworks that emit more than 140 dB (see graph), can rupture the membrane of the eardrum and cause immediate hearing loss.
“Besides hearing disorders, the greater the noise levels that people are exposed to, the greater the risk of developing cardiovascular and metabolic diseases,” reports speech therapist Alessandra Giannella Samelli, of the School of Medicine of the University of São Paulo (FM-USP). The researcher sought to measure these impacts in a project funded by FAPESP, completed in 2023. In the study, she analyzed the changes caused in individuals exposed to different levels of noise through electrophysiological tests that assess the autonomic nervous system, influenced by hormonal variations and neurotransmitters. The preliminary results suggest that there is an increase in respiratory rate, heart rate, and sweating associated with greater subjective discomfort, in situations with higher noise levels. In her opinion, the autonomic nervous system regulates the functioning of the cardiac, respiratory, and digestive organs. “It is as if the person exposed to excessive noise remains on constant alert,” she compares. Over time, this situation creates an imbalance in the body that, in extreme cases, can cause problems such as myocardial infarction, stroke, and metabolic disorders. Samelli explains that different studies published in 2011 in the document “Burden of disease from environmental noise,” by the WHO, demonstrated this association.
Having researched urban noise for around 20 years, Portuguese sociologist Carlos Fortuna, of the University of Coimbra, in Portugal, observes that noise pollution makes city dwellers live amidst a “cloud of noise,” which blocks out the specific sounds of neighborhoods and impairs communication between people. In an interview with Pesquisa FAPESP, the expert commented that the acoustics of European cities began to change at the end of the nineteenth century. “With the intensification of the industrialization process, urban noise, previously characterized by human voices and animal sounds, was substituted for persistent metallic and industrial noise,” he says. Fortuna explains that, by law, municipal governments in Portugal are required to produce urban noise maps.
A study conducted since 2019 by Araújo, of UFRN, has sought to identify which Brazilian cities have implemented actions to map noise pollution. The study found that Belém (Pará) and Fortaleza (Ceará) were the first cities to develop noise maps, between 2002 and 2004, through municipal government initiatives. In the case of Natal, architect Débora Nogueira Pinto Florência defended her PhD thesis in which she produced the noise map for the city, in 2018 at UFRN. In the same year, Cáceres (Mato Grosso) also produced a noise map, through the initiative of the municipal government. “When production of the map is mandatory, as is the case in European cities with over 250,000 inhabitants, opportunities and contexts are created for its implementation, but when it is not, this initiative is left to the discretion of the local public authorities,” comments Araújo. According to the researcher, the city of Fortaleza, for example, was mapped by the municipality due to the work of a technician who understood the subject. “He convinced the decision-makers that the map would be an important tool for managing the issue of noise pollution,” he observes.
Léo Ramos Chaves / Revista Pesquisa FAPESPAn apartment on the elevated Presidente João Goulart expressway, known as the Minhocão (meaning big worm in English), in the city of São Paulo. Traffic, followed by noise from industries, and outdoor shows and events are the main sources of noise pollutionLéo Ramos Chaves / Revista Pesquisa FAPESP
In 2016, the city of São Paulo passed Law No. 16.499 to create its noise map, something that should have occurred by 2023. However, the document was not produced and the city government extended the deadline, issuing Ordinance No. 16/2024 to establish a management group responsible for developing the document by 2030. Rio de Janeiro has also enacted legislation in this regard, Law No. 7.479/2022, which obliges the Executive Branch to produce an urban noise map. “Despite the few initiatives developed by municipal governments to record the city-wide noise, many municipalities, especially in state capitals in the Northeast and South of Brazil, have already mapped specific neighborhoods and isolated streets,” states the architect. Among these cities are Salvador (Bahia), Recife (Pernambuco), João Pessoa (Paraíba), Maceió (Alagoas), and Santa Maria and Porto Alegre, both in Rio Grande do Sul. Noise maps are made using software that employs color scales to indicate sounds of different intensities. To create these documents, municipal governments need to have georeferenced cartographic bases and send a team of technicians into the streets to measure the sources of noise and their intensities, as well as counting vehicles, at different points across the municipality.
Araújo, of UFRN, feels that this tool is rarely used in Brazil, among other factors, due to the lack of national laws and technical standards making it mandatory. However, as the researcher records, despite the lack of specific legislation for noise maps, the country counts on three technical standards that help regulate the emission of noise. One of them is NBR 15.575, of 2013, which deals with issues related to habitation, one being acoustics. “The standard stipulates that residences must have facades made with specific thicknesses and materials to ensure a certain level of acoustic insulation within their interiors,” she explains. There is also NBR 10.152, from 2017, which establishes internal sound pressure levels to be met within each area of the residences. Additionally, NBR 10.151, from 2019, stipulates that the noise from sound sources in communal areas, predominantly residential ones, must not surpass the limit of 55 dB during the day and 50 dB at night.
Ericson M. Scorsim, jurist and doctor of law from USP and author of the book Sustentabilidade ambiental acústica – Propostas regulatórias para cidades livres de ruídos excessivos (Environmental acoustic sustainability: Regulatory proposals for cities free from excessive noise; the author’s own publishing company, 2024), remembers that there are specific rules in Brazil, such as the case of Law No. 15.585/2019, from Curitiba (Paraná), which prohibits the use of fireworks within the city. Another example from Curitiba is Law 10.625, from 2002, which deals with urban noise, well-being, and public peace. “However, this law is outdated and requires revision,” he comments. In São Paulo there is the Law of Silence, regulated by Decree No. 57.443/2016, which inspects the noise emitted by commercial establishments, such as bars, nightclubs, and restaurants, as well as industries and religious temples. “This type of measure brings important advancements, but the enactment of new laws with more rigorous standards for controlling the emission of noise is essential,” defends the jurist.
Rubens Cavallari / FolhapressMunicipalities such as São Paulo have legislation to regulate the noise emitted by commercial establishments, such as bars and nightclubsRubens Cavallari / Folhapress
Researchers from the fields of architecture and urbanism and engineering have been working hard to find solutions for urban noise problems. According to engineer Sylvio Reynaldo Bistafa, a retired professor of the School of Architecture and Urbanism (FAU) of USP, the main source of noise from cities today is traffic, followed by industrial plants, concerts, and outdoor events. One of the recent cases for which he created alternatives involves a paper and cellulose factory, whose production machinery was outdoors. When the unit was created in Greater Porto Alegre, the region was predominantly rural. However, with the advancement of urbanization, the area, which previously housed only small farms and country houses, has become full of residences. The noise from the factory began to disturb the neighbors, who reported it to the Public Prosecutor’s Office.
Contracted by the company to seek solutions for the problem, Bistafa suggested the installation of an acoustic barrier (i.e., a wall to contain the sound) around the industrial plant, as well as the installation of specific sound barriers on the machinery. These structures are made from perforated galvanized steel, electroplated and filled with rock wool. With resistance to adverse weather conditions, they have a great capacity for absorbing noise.
“The company adopted the barrier around the factory, but did not modify the equipment, which was worth millions of dollars. With the modifications, they would have lost the warranty and the maintenance costs would have become unviable,” he explains. With this, the noise emitted today by the factory is within the limits established by NBR 10.151 for daytime, but not for nighttime hours. Despite this fact, the Public Prosecutor’s Office has allowed the unit to continue operating, because closing the factory would result in financial impacts on the community, since many of the residents work there. “The case shows how noise control engineering presents potential and limitations,” ponders the researcher.
In turn, Araújo, of UFRN, carried out her PhD research funded by FAPESP at FAU-USP, completed in 2009, to seek solutions for buildings that require ventilation, natural lighting, and noise insulation without using energy. “Cobogós [perforated concrete blocks], architectural structures frequently used in the walls of buildings and residences and for dividing environments, help reduce heat and humidity, since they allow the passage of natural ventilation, and, at the same time, due to being perforated, end up aiding the entry of noise,” she explains. In the study, Araújo developed a prototype cobogó that, in addition to providing illumination and ventilation, also mitigates the entry of external noise.
Araújo is currently preparing to file the patent application for the product and is working on updating the noise map of Natal, with the proposal of creating a partnership with the municipal government. As highlighted by the architect, urban noise represents the second worst type of pollution, according to the WHO, being surpassed only by atmospheric pollution. “Cities must create specific action plans to mitigate the problem or incorporate these measures into their master plans, which are currently the main tools for urban space management,” she adds.
Projects
1. Extra-auditory effects of noise: Subjective and electrophysiological stress indices (nº 21/04542-9); Grant Mechanism Regular Research Grant; Principal Investigator Alessandra Giannella Samelli (USP); Investment R$109,357.13.
2. Proposal for the development of a hollow acoustic element (nº 05/59917-4); Grant Mechanism Doctoral Fellowship; Supervisor Sylvio Reynaldo Bistafa; Beneficiary Bianca Carla Dantas de Araújo; Investment R$92,449.88.
Scientific articles
BRASILEIRO, T. da C. et al. Mapas de ruído: Histórico e levantamento da atual produção brasileira. Acústica e Vibrações. 34 (51). 2019.
HILLESHEIM, D. et al. Prevalência e fatores associados a atividades que levam ao nervosismo no trabalho no Brasil: Estudo com dados da Pesquisa Nacional de Saúde, 2013. Revista Brasileira de Saúde Ocupacional. vol. 48. 2023.
HILLESHEIM, D. et al. Perda auditiva induzida por ruído no Brasil: Descrição de 14 anos de notificação. Audiology – Communication Research, vol. 27. 2022.
FORTUNA, C. O mundo social do ruído. Contributos para uma abordagem sociológica. Análise Social. Revista do Instituto de Ciências Sociais da Universidade de Lisboa. vol. 55, no. 234. 2020.
Book
SCORSIM, E. Sustentabilidade ambiental acústica – Propostas regulatórias para cidades livres de ruídos excessivos. Curitiba: Author Published. 2024.
Documents
Frontiers 2022: Noise, blazes and mismatches – Emerging issues of environmental concern. United Nations Environment Programme. Nairobi, 2022. Office for Europe, 2011.
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