Doctoral thesis links environmental noise to weight gain, heart damage

Environmental noise can trigger stress and sleep disturbances that affect metabolism and cardiovascular health, according to a doctoral thesis by Triin Veber, an environmental health specialist at the University of Tartu, ERR reported.

Environmental noise includes pollution from air traffic, industry, cars and railways. Although it is not usually loud enough to cause direct hearing damage, a growing number of epidemiological studies link it to the development of chronic diseases.

Veber said the body’s stress response to noise has an evolutionary basis. When a person hears a sudden sound while sleeping, the body prepares to wake up and escape. Stress hormones are released into the bloodstream, blood pressure rises and metabolism changes to help the person flee quickly.

A short-term stress response is not necessarily harmful, Veber said. Problems can arise when the stress system is activated too often or does not switch off sufficiently.

Today, people may react to a motorcycle passing beneath a window at night in much the same way their ancestors reacted to a cracking branch and a possible predator. Even when a person does not wake up, analyses show that the process can also begin during sleep.

If these minor disturbances recur night after night and year after year, sleep becomes less deep and less restorative. Over time, this may lead to cardiovascular disease and metabolic disorders.

Noise levels in Tallinn and Tartu

According to research, environmental noise becomes harmful at an annual average level of about 50 to 55 decibels, roughly the volume of ordinary conversation. Concerts, by comparison, can reach 90 to 100 decibels.

The annual average reflects the combined effect of occasional cars passing beneath windows at night and higher noise levels during daytime rush hours, Veber said.

For her doctoral thesis, Veber analysed noise maps for Tallinn and Tartu. The maps model residents’ average exposure based on buildings and terrain. Using 2015 data, she found that 61.4 percent of Tallinn residents and 60 percent of Tartu residents lived in areas with noise levels above 55 decibels.

Novaator also conducted an amateur science experiment to assess the noise levels at traffic hubs in Tallinn and Tartu.