Extreme Temperature Events, Fine Particulate Matter, and Myocardial Infarction Mortality

Area of Science:

• Environmental Health
• Cardiovascular Epidemiology
• Air Pollution Research

Background:

• Extreme temperature events (ETEs), such as heat waves and cold spells, are linked to myocardial infarction (MI) morbidity, but their impact on MI mortality requires further investigation.
• The synergistic effects of ambient fine particulate matter (PM2.5) and ETEs on cardiovascular mortality are suggested but not well-established for MI deaths.

Purpose of the Study:

• To investigate the association between exposure to ETEs and PM2.5 and MI mortality.
• To evaluate the interactive effects of ETEs and PM2.5 on triggering MI deaths.

Main Methods:

• A time-stratified case-crossover study analyzed 202,678 MI deaths in Jiangsu province, China (2015-2020).
• Multiple ETE definitions based on temperature thresholds and durations were used.
• Exposure-response analyses were conducted using conditional logistic regression to estimate interaction effects.

Main Results:

• Both heat waves and cold spells were associated with increased MI mortality odds.
• PM2.5 exposure was significantly linked to higher MI mortality odds, with effects diminishing at higher concentrations.
• A significant synergistic interaction was found between heat waves and PM2.5 on MI mortality, but not for cold spells.
• Heat wave and PM2.5 combined accounted for up to 2.8% of MI deaths exceeding WHO interim target 3 levels.
• Women and older adults exhibited higher vulnerability to these exposures.

Conclusions:

• Exposure to ETEs and PM2.5 significantly increases MI mortality risk, with synergistic interaction observed between heat waves and PM2.5.
• Mitigating both ETEs and PM2.5 exposures may offer significant public health benefits by reducing premature MI deaths.
• Targeted interventions may be necessary for vulnerable populations like women and the elderly.