Exposure to extreme heat and high levels of PM2.5 significantly increases the risk of fatal heart attacks, each through unique mechanisms.
Extreme Heat
Long-term exposure to extreme heat can lead to chronic health risks, including increased risks of renal, liver, and cardiovascular diseases over 12-14 years. A single episode of heat stroke can induce chronic health disorders such as obesity, cardiac hypertrophy, liver steatosis, and metabolic inflexibility, especially when combined with a high-fat diet. Heatstroke can also cause sustained multi-organ dysfunction, leading to myocardial metabolic irregularities and early heart disease.
High PM2.5 Levels
Exposure to PM2.5 is strongly associated with adverse cardiovascular outcomes, including increased risk of mortality, stroke, heart failure, myocardial infarction, and cardiac arrhythmias. Long-term exposure to PM2.5 increases the risk of incident acute myocardial infarction (AMI) and ischemic heart disease (IHD) mortality. The primary mechanisms through which PM2.5 influences cardiovascular events include oxidative stress and systemic inflammation, direct translocation into systemic circulation, and perturbation of the autonomic nervous system (ANS).
Combined Impact
While both extreme heat and high PM2.5 levels independently increase the risk of fatal heart attacks, their combined impact could potentially exacerbate cardiovascular risks. Individuals exposed to both extreme heat and high levels of air pollution may experience a synergistic effect, increasing their vulnerability to cardiovascular events. However, the exact nature of this combined impact would require further research to fully understand.
Given these risks, maintaining vigilance over weather conditions and air quality becomes crucial. Those at risk, such as the elderly, individuals with pre-existing heart conditions, and even young people, should take appropriate precautions during periods of extreme heat and high particulate matter levels. This includes staying indoors when necessary, using air purifiers, and being mindful of clothing choices to promote heat dissipation.
[1] Chae, Y. O., et al. "Exertional Heat Stroke Induces Metabolic Disorders and Cardiac Remodeling in a Diet-Induced Obesity Mouse Model." PLOS One, vol. 14, no. 1, 2019.
[2] Brokamp, C., et al. "The Association between Long-Term Exposure to Particulate Matter and Cardiovascular Disease Mortality: A Systematic Review and Meta-Analysis of Ecological Studies." Environmental Health Perspectives, vol. 129, no. 11, 2021.
[3] Ramanathan, C., et al. "Investigating the Association between Ambient Fine Particulate Air Pollution (PM2.5) and Cardiovascular Disease Outcomes: A Systematic Review and Meta-Analysis of Cohort Studies." Environmental Pollution, vol. 261, 2019.
