Air pollution + extreme heat = double the risk of a heart attack
A study of 202, 678 heart attack deaths in Jiangsu province, China, from 2015 to 2020 found that days that had extreme heat, extreme cold or high levels of PM2.5 air pollution were significantly associated with the risk of death from a heart attack, especially in women and older adults.
Significantly, days that had a combination of both extreme heat and high levels of PM2.5 provided the greatest risk of heart attacks.
Data was collected of the temperature and air pollution levels prior to a heart attack death and compared to control days. PM2.5 levels above 37.5µg/m³ were deemed to be ‘high’.
Extreme temperatures were determined by the daily heat index for an area, which captures the combined effect of both heat and humidity. The duration and extremity of the hot and cold conditions was also taken into account.
Yuewei Liu, an associate professor of epidemiology in the School of Public Health at Sun Yat-sen University in Guangzhou, China said: ‘Extreme temperature events are becoming more frequent, longer and more intense, and their adverse health effects have drawn growing concern. Another environmental issue worldwide is the presence of fine particulate matter in the air, which may interact synergistically with extreme temperatures to adversely affect cardiovascular health.
‘Our findings provide evidence that reducing exposure to both extreme temperatures and fine particulate pollution may be useful to prevent premature deaths from heart attack, especially for women and older adults.’
Compared with control days, the risk of a fatal heart attack was observed to be twice as high during four-day heat waves that had PM2.5 levels above 37.5µg/m³. Days with high levels of fine particulate pollution during cold snaps did not have an equivalent increase in the risk of heart attack death.
Heart attack deaths were also found to be higher among people over 80 than in younger adults during heat waves, cold snaps or days with high levels of fine particulate pollution.
The researchers estimated that up to 2.8% of heart attack deaths may be attributed to the combination of extreme temperatures and high levels of fine particulate pollution.
