NOISE has become synonymous with big cities. Far from being a simple irritant, noise pollution has developed into a public health problem, affecting human health, and disturbing the daily life of millions.

From New York and London to Karachi, Jakarta, Dhaka and Mumbai, the daily hustle and bustle of crowded streets and the rumbling of vehicular traffic, rail tracks and busy skies are contributing not just to a rise in emissions in megacities, but also noise pollution.

The WHO puts the acceptable level of noise in residential areas at 55 decibels and 70 decibels for all other areas. Population growth and urbanisation have blurred the distinction between residential and commercial zones in many developing countries. The problem has reached alarming proportions as heavy traffic, construction works and industry located in the proximity of human settlements push noise pressure to levels f ar exceeding WHO guidelines.

Experts now estimate that the consequences of noise pollution on human health are second only to air pollution. Hearing impairment and effects on sleep, quality of life, mental health and well-being are associated with noise. UNEP`s report Frontiers 2022: Noise, Blazes and Mismatches analyses the harmful ef fects of noise. The report singles out traf fic noise exposure as a `risk f actor for the development of cardiovascular and metabolic disorders such as elevated blood pressure, arterial hypertension, coronary heart disease and diabetes` and adds that `a conservative estimate indicates that long-term exposure to environmental noise contributes to 48,000 new cases of ischemic heart disease and causes 12,000 premature deaths annually in Europe`. A recent study in France found that noise pollution affected the health of around nine million people in the country, while up to 156 billion euros was the estimated cost of dealing with the ef fects of noise pollution in France.

Noise pressure levels in cities across Pakistan have risen exponentially in recent years as unplanned and unmanaged urbanisation continues to swell the urban sprawl.

Small towns are also becoming unlivable. In violation of municipal bylaws, residential areas are commercialised. Except for some posh townships, it is difficult to differentiate between a residential and commercial locality. Offices, shopping plazas and autorepair workshops surround even schools, universities and hospitals places which should always be protected from noise pollution. Ear-splitting noise from unmuffled motorbikes, auto rickshaws and public transport is harmful in more than one way.

Besides causing physical impairment, excessive noise leads to psychologicaleffects, and changesin socialbehaviour by interfering with daily routines.

In developed countries, municipal authoritarians strictly enforce regulations to protect people especially schoolchildren and patients in hospitals from most sources of noises. The general public is alert and closely monitors any deviation from noise control measures and regulations. In contrast, the lack of public awareness, inadequacy of noise emission standards, and poor enforcement of existing laws and regulations are compounding noise pollution challenges in some developing countries.

Current rules of fer little by way of ef fective control measures or penalties for polluters.

The answer to addressing this growing menace lies in adopting a comprehensive and consistent policy approach to noise pollution management which combines the principles of precaution, prevention and polluter pays. Environment and health authorities will need to collaborate with the civic administration to monitor noise levels, compile data on the sources and effects ofnoise pollution and raise public awareness through the electronic and social media.

Local governments must take steps through the strict enforcement of regulations and newlaws to hold noise polluters accountable.

Cities can also take practical steps by installation of road or rail noise barriers and reducing noise at source from construction and industry. Other measures that can contribute significantly to noise reduction in cities include the pedestrianisation of streets, taking old vehicles off the roads, promoting cycling and putting in place infrastructure for electric cars and electric motorbikes. Trees and green belts serve the dual purpose of filtering dirty air and absorbing noise. It was not without purpose that in days past, city roads were lined with trees and buf fered with green belts.

By 2050, 68pc of the global population will be living in cities. Pakistan has the highest rate of urbanisation in South Asia, portending a rapid increase in urban population in the next decade. Unless managed, noise pollution could contribute to a public health crisis. Ensuring reduced noise levels, especially in our cities, must become a priority. • The writer is director of intergovernmental affairs, United Nations Environment Programme.