The study analyzed heart attack rates of nearly 16,000 New Jersey residents hospitalized for a heart attack in 2018 using data from the MIDAS database, an archive of all cardiovascular hospitalizations in the state. Average daily traffic noise at home was calculated using data from the state’s Bureau of Transportation Statistics.
Patients were divided into those with high traffic noise levels (average 65 decibels or higher throughout the day) and those with low noise exposure (average daily less than 50 decibels). The noise level of 65 decibels is similar to a loud conversation or laughter. Since noise levels are averaged over the course of the day, Moreyra says many people may have experienced periods of relative quiet interrupted by louder bangs like trucks, trains or airplanes. pass.
The overall results show that 5% of heart attack hospitalizations are due to high noise levels in the state. Heart attack rates were 72 percent higher in places exposed to high traffic noise, with these areas having 3,336 heart attacks per 100,000 people compared with 1,938 heart attacks per 100,000 people in quieter areas. Based on the relative rates of heart attacks at different locations, the researchers calculated that exposure to high-pitched noise accounted for about 1 in 20 heart attacks in this state.
The study is one of the first to examine noise and heart disease in the US, but the findings are in line with several earlier studies done in Europe. New Jersey is a state with many dense urban areas, close to roads, railroads, and three major airports. Moreyra said other metropolitan areas with similar infrastructure and traffic noise are likely to see a similar pattern.
“As cardiologists, we often think about many of the traditional risk factors like smoking, high blood pressure or diabetes,” says Moreyra. “This study and others suggest that maybe we should start thinking about air pollution and noise pollution as additional risk factors for cardiovascular disease.”
Although the study did not investigate the biological mechanisms behind the link, Moreyra said noise can cause chronic stress, sleep disturbances and emotional distress such as anxiety and depression, possibly affect heart health. Chronic stress is known to cause hormonal changes linked to inflammation and changes in blood vessels that are linked to heart disease.
Living close to roads and other transportation infrastructure also means being exposed to more vehicle smoke and other forms of particulate air pollution. Previous studies have linked particulate air pollution to cardiovascular damage and increased rates of heart disease.
“Air pollution and noise go hand in hand,” says Moreyra. “The question is: what percentage of this effect is due to particulate pollution, and how much is noise?”
Researchers are beginning to untangle those factors, but Moreyra said further studies are needed to unravel the impact of noise pollution on heart health.
The researchers did not attempt to account for demographic, socioeconomic, or other health risk factors in their analysis, and they suggest that further research could help discern the effect. of noise pollution with these other factors. Additionally, Moreyra said the study did not take into account noise exposure at work or other locations. As a next step, the team plans to examine the data in more detail to gain insight into which sources of traffic noise can have the greatest health impact.
Moreyra says that a range of policy interventions can help reduce an individual’s exposure to traffic noise at home, even in urban areas. Examples include better enforcement of noise regulations, infrastructure to block road noise, air traffic rules, low-noise tires for vehicles, and ways to better acoustics for buildings.