Euronews.green writes that researchers previously linked hot weather to dangerous health problems, such as cardiovascular diseases, as well as stroke, as per Dr Daniel W Riggs, an epidemiologist and an assistant professor in the division of environmental medicine at the University of Louisville School of Medicine in Kentucky.

Inflammation, part of the body's response to an infection or injury, is associated with heart risk and this immune response is triggered by cytokines, proteins that are released by some of the blood cells.

Riggs' team of researchers took blood samples from 624 people who were part of the Green Heart Project, which studied how planting greenery can reduce exposure to pollution and the chance of developing cardiovascular disease.

Scientists measured 11 types of cytokines and nine types of immune cells and adjusted the results based on things like age, sex and race, which led to the discovery that indeed hot weather is indeed responsible for increased levels of several cytokines. One of them, TNF-alpha, says Riggs, represents "one of the major inflammatory markers and plays an important role in cardiovascular disease."

High temperatures were also associated with higher levels of some classes of white cells, also known as monocytes, suggesting that heat indeed triggers inflammation as an immune response.

The researchers were mostly surprised about the fact that great changes took place in the cell structure after short-term exposures to hot weather.

Dr Judith Lichtman, chair of the department of chronic disease epidemiology at Yale School of Public Health in New Haven, Connecticut, said that "what's so valuable about this study is they're really trying to understand, at the body level, the mechanisms that may be contributing to this increased risk."

While the study was conducted in a small area, on people who mostly spent time outside, not in a shaded, air-conditioned place, the results must be taken with a pinch of salt, but this can open up new research potential in the future.