Very Hot, Polluted Days Raise Heart-Attack Risk.

"Extreme heat and air pollution can be dangerous for the heart. Enduring both at the same time can be especially deadly, new research shows.

The risk of having a fatal heart attack doubles during heat waves that last several days and overlap with periods of poor air quality, according to an analysis of heart-attack deaths published Monday in the journal Circulation.

On their own, higher-than-normal temperatures or air pollution increased the risk of deadly heart attacks, showed the analysis of more than 200,000 heart-attack fatalities between 2015 and 2020 in the Chinese province of Jiangsu. But when both occurred simultaneously, they were found to amplify each other's effects.

High temperatures and polluted air have been linked in studies to both short-term and chronic health problems, including heart and kidney disease, and cognitive issues. Older people, smokers and people with heart disease, high blood pressure, diabetes or other conditions are especially vulnerable.

For the recent analysis, researchers in China and the U.S. used a statistical technique to uncover possible links between the incidence of fatal heart attacks in Jiangsu and hotter- or colder-than-average temperatures, as well as poor air quality. Air quality was considered poor when concentrations of fine particulate matter, a type of pollutant, exceeded a 24-hour average of 37.5 micrograms per cubic meter of air. Fine particulate matter, also known as PM2.5, is defined as particles that are 2.5 micrometers or less in diameter.

Risk of a deadly heart attack increased the higher the heat and the more prolonged it was, the study found. Two consecutive days of temperatures at around 100 degrees Fahrenheit increased the risk of fatal heart attack by 30%, researchers said. Four days in a row of similar heat increased the risk by 50%.

Exposure to high levels of PM2.5 on its own was associated with a 2% increased risk of deadly heart attacks, the study said. When high-heat days coincided with poor air quality, the risk shot up significantly. Two days in a row of 100-degree heat, plus polluted air, was associated with an 84% increased risk. Four consecutive days of similar heat and pollution doubled the risk, the paper showed.

Very cold temperatures also enhanced the risk of fatal heart attacks, the analysis said, though slightly less than very warm days." [1]

1. U.S. News: Very Hot, Polluted Days Raise Heart-Attack Risk. Mosbergen, Dominique. 
Wall Street Journal, Eastern edition; New York, N.Y. [New York, N.Y]. 25 July 2023: A.3.