Short-term air pollution exposure appears to confer greater risk for MI mortality
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Those exposed to short-term ambient air pollution demonstrated elevated risk for MI mortality, researchers reported.
“Exposure to ambient air pollutants has been linked to increased cardiovascular morbidity and mortality and continues to be a public health concern worldwide,” Yuewei Liu, MD, PhD, associate professor in the department of epidemiology at the School of Public Health at Sun Yat-sen University in Guangzhou, China, and colleagues wrote. “Because MI is a leading cause of death that accounts for over 30% of all deaths from ischemic heart diseases, it is of great importance to understand whether air pollutant exposures also trigger deaths from MI.”
Researchers conducted a time-stratified case-crossover study investigating 151,608 (mean age, 75 years; 54% men) MI death cases in Hubei province, China, from 2013 to 2018. Exposure to particulate matter with an aerodynamic diameter of 2.5 m or less (PM2.5), an aerodynamic diameter of 10 m or less (PM10), sulfur dioxide, nitrogen dioxide, carbon monoxide and ozone based on each case’s home address and control days were assessed at neighboring air quality monitoring stations.
MI mortality risk
Exposure to air pollution was associated with increased odds for MI mortality for both PM2.5 (P for nonlinear trend < .001) and PM10 (P for nonlinear trend = .006). These odds demonstrated a significant increase before a breakpoint of 33.3 g/m3 for PM2.5 and 57.3 g/m3 for PM10 and flattened at higher exposure levels. The association for nitrogen dioxide exposure was almost linear.
Researchers observed a significant association with a 4.14% (95% CI, 1.25-7.12) increase in odds of MI mortality for PM2.5, 2.67% (95% CI, 0.8-4.57) for PM10 and 1.46% (95% CI, 0.76-2.17) for nitrogen dioxide after each 10 g/m3 increase in air pollution exposure.
Nitrogen dioxide exposure and MI mortality demonstrated a significantly stronger association in adults aged at least 75 years (percent change in odds, 2.24%; 95% CI, 1.39-3.1) compared with adults younger than 75 years (percent change in odds, 0.36%; 95% CI, –0.64 to 1.38; P for effect modification = .006).
Acute adverse effects
“These findings add to the understanding of acute adverse effects of air pollution on cardiovascular mortality and highlight the needs for either general population or policy practitioners to take effective measures in reducing air pollution exposures, especially for older adults and those with higher risk of MI occurrence,” the researchers wrote.
According to an accompanying editorial, despite the abundance of consistent evidence, lingering concerns include exposure misclassification, residual confounding, exposures to other toxicants and other poorly recognized co-exposures continue.
“These studies have further provided a time scale of rapid reversibility of air pollution-mediated morbidity and mortality,” Sanjay Rajagopalan, MD, director of the Cardiovascular Research Institute and professor in the department of medicine at Case Western Reserve University School of Medicine in Cleveland, and Cardiology Today Editorial Board Member Jagat Narula, MD, PhD, associate dean of global health and professor of cardiology and radiology at Icahn School of Medicine at Mount Sinai, wrote in the editorial. “As part of a though experiment, immediate elimination of all fossil fuel emissions could save 3.61 million deaths within the ensuing year.”
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