Air pollution is a global environmental crisis that has been linked to an estimated 9 million premature deaths per year, according to The Lancet Commission on Pollution and Health. WHO has estimated that up to 12.6 million global deaths/year are due to living in unhealthy environments. The Global Burden of Disease (GBD) Study in 2019 updated these estimates, indicating that air pollution was responsible for 268 million disability-adjusted life years (DALYs).
The harmful effects of air pollution are largely due to fine particulate matter (PM2.5) and reactive gases such as ozone and nitrogen dioxide. It is also associated with an increased risk of cardiovascular morbidity and mortality, as well as mental health issues, cognitive impairment, and dementia. In addition to the health risks of air pollution, environmental noise is another transport-related health risk factor. According to WHO, at least 1.6 million healthy life years are lost annually from traffic noise in Western Europe.
Research suggests that the social cost of noise and air pollution in the EU — including excess death and disease — could be more than 1 trillion EUR. To address this issue, scientists have used a custom-built Inhalation system for mice from TSE Systems to investigate single and combined exposure of mice to aircraft noise and airborne particulate matter (APM).
A total of 172 male C57BL/6J mice were exposed to either APM only, noise only, a combination of APM and noise, or to clean air and no noise. Additionally, 34 male C57BL/6J mice were exposed to either clean air, NIST1, NIST2, or NIST3 for 6 h per day for 3 days. The target concentration of particles in the chamber was 200 μg/m3. Mice were exposed to a loop of 69 aircraft noise events for 9 ± 3 h per day for 3 days. All exposures occurred during the daytime.
In summary, this study provides evidence for the deleterious effects of noise and/or APM on different organs, particularly on the lungs and brain. The researchers have shown a clear additive effect of combining noise and APM, which is of particular importance in the context of air pollution and transportation noise exposure in cities. The results also suggest that specific stress pathways are induced by noise and/or APM single exposure and co-exposure, and that these pathways may interact with each other, in a non-linear fashion.
These findings provide important insights into adverse health effects that can be caused by combined environmental exposures.
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