- Heat and pollution can be a deadly combination that would affect the population
Although there are various factors that can double the risk of heart attack, there is a combination that is especially deadly: heat and high levels of pollution by fine particles, two elements that trigger the risk of death, especially in the elderly and women.
This is the main conclusion of a study published this Monday in Circulation, based on the analysis of more than 202,000 deaths from myocardial infarction between 2015-2020 in the Chinese province of Jiangsu, a region with four distinct seasons and a wide range of seasons. of temperatures and levels of contamination by fine particles.
Fine particles less than 2.5 microns in size come from car exhaust, factories or fires, and inhalation causes heart disease and stroke among other problems.
These particles “can interact synergistically with extreme temperatures and negatively affect cardiovascular health,” said lead author Yuewei Liu, a researcher at the Sun Yat-sen University School of Public Health in Guangzhou, China.
To find out if joint exposure to extreme temperatures and pollution affects health, the team analyzed more than 202,000 heart attack deaths between 2015-2020 in Jiangsu.
The study confirmed that the days that combined extreme heat and high levels of air pollution by fine particles increased the risk of death by heart attack, more in women than in men and in older adults more than in young people.
Specifically, the deaths occurred among adults with a mean age of 77.6 years, 52 percent were over 80 years of age, and 52 percent were male.
Extreme temperatures were measured based on an area’s daily heat index that includes the combined effect of heat and humidity. And both the duration and intensity of heat waves and cold waves were assessed.
Deaths from myocardial infarction, or case-days, during these periods were compared with control days on the same weekday of the same month, that is, if a death occurred on a Wednesday, then every other Wednesday of the same month. control days would be considered.
Particle levels were considered high on any day with a mean fine particulate level greater than 37.5 micrograms per cubic meter.
Compared with control days, the risk of fatal heart attack increased by 18 percent in 2-day heat waves with heat indices at or above the 90th percentile (28.1 to 36.6 degrees Celsius), and up to 74 percent more in 4-day heat waves with heat indices equal to or greater than the 97.5th percentile (between 34.8 and 43 degrees C).
Cold-related heart attacks were 4% more frequent during 2-day cold waves with temperatures equal to or less than the 10th percentile (between 0.7 and 4.7 degrees), and 12% more frequent in 3-day cold waves days with temperatures equal to or less than the 2.5th percentile (between -2.7 and 2.7 degrees Celsius).
But with pollution above 37.5 micrograms per cubic meter, deaths increased in 4-day heat waves but not in cold ones.
By sex and age, more deaths were detected among women than among men during heat waves and among people aged 80 and over.
The median age of all individuals who died of a heart attack in Jiangsu between 2015 and 2020, even during non-extreme temperature events, was 77.6 years; 52.1% of these individuals were over 80 years of age.