A new study found that people who were exposed to higher levels of noise from aircraft were more likely to have a higher body mass index, an indicator for obesity that can lead to stroke or hypertension. The findings highlight how the environment — and environmental injustices — can shape health outcomes.
Research has shown that noise from airplanes and helicopters flying overhead are far more bothersome to people than noise from other modes of transportation, and a growing body of research suggests that aircraft noise is also contributing to negative health outcomes.
One of the latest studies, led by Boston University School of Public Health (BUSPH) and Oregon State University (OSU) indicates that airplane noise may increase one’s risk of developing cardiometabolic diseases, a cluster of conditions such as heart attack, stroke, diabetes, and hypertension.
Published in the journal Environment International, the study found that people who were exposed to airplane noise levels at 45 dB or more were more likely to have higher self-reported body mass index (BMI), with the highest BMI measures linked to aircraft noise levels at 55 dB or above. Airplane noise exposure at 45 dB or above was also associated with having higher BMI in middle to late adulthood from early adulthood. For comparison, the sound of a whisper is 30 dB, a library setting is 40 dB, and a typical conversation at home is 50 dB.
BMI is an indicator of general obesity, which can lead to cardiometabolic diseases, as well as a range of other health issues. The study is the first to explore a connection between aircraft noise exposure and obesity nationwide in the United States; past studies on this subject have focused on European populations, and results have varied.
“Prior research has shown that aircraft noise can elevate stress responses and disturb sleep, but there has been mixed evidence of any links with body mass index,” says study lead and corresponding author Dr. Matthew Bozigar, assistant professor of epidemiology at OSU. “We were surprised to see a fairly robust link between aircraft noise and higher body mass index among women across the US.”
These new findings underscore the role of the environment on one’s risk of chronic disease.
‘Obesity has become very stigmatized, but what is important to remember is that it is linked with poor cardiometabolic health outcomes, and that it has strong environmental drivers,” Dr. Bozigar says. “This is disheartening, but also promising, in the sense that we could potentially enact policies to mitigate these drivers of obesity.”
For the study, Dr. Bozigar and colleagues examined airplane noise exposure and self-reported BMI and other individual characteristics among nearly 75,000 participants living around 90 of the major US airports. The participants were selected from the Nurses’ Health Studies (NHS), ongoing, prospective studies of US female nurses who have completed biennial questionnaires since the 1970s and 1980s.
The team examined aircraft noise levels every five years from 1995 to 2010, using a day-night estimate (DNL) that captures the average noise level over a 24-hour period and applies a 10 dB adjustment for aircraft noise occurring at night, when background noise is low. The current policy-related threshold for significant noise impacts is above DNL 65 dB. The team assessed BMI measures at multiple thresholds below that (less than 45 dB; 45-54 dB; 55 dB and above; and continuous exposure at 45 dB or above) for the nurses’ geocoded residential addresses.
Although the team acknowledges that BMI is a suboptimal metric, the independent and strong association between more aircraft noise exposure and higher BMI that they observed is notable. There were also regional differences, with stronger associations among participants on the West Coast and those who live in arid conditions.
“We can only hypothesize about why we saw these regional variations, but one reason may relate to the era of regional development, building characteristics, and climate which may affect factors such as housing age, design, and level of insulation,” says study senior author Dr. Junenette Peters, associate professor of environmental health at BUSPH. “Regional differences in temperature and humidity may influence behaviors such as window opening, so perhaps study participants living in the West were more exposed to aircraft noise due to open windows or housing type, which allowed more noise to penetrate.”
Similarly, the stronger associations observed in arid climates, many of which are also in the Western US, may relate to the way noise travels under various atmospheric conditions, Dr. Peters says.
Future research should explore this link between aircraft noise exposure and obesity further, as well as broader inequities in environmental noise exposure, particularly among other populations. Previous data suggest that Black, Hispanic, and low-income populations are disproportionately exposed to aircraft noise. The participants in the NHS study groups were primarily White and of mid-level socioeconomic status.
“We need to study the potential health impacts of environmental injustices in transportation noise exposures alongside other environmental drivers of poor health outcomes” Dr. Bozigar says. “There is a lot more to figure out, but this study adds evidence to a growing body of literature that noise negatively impacts health.”