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Soaring temperatures and heavy pollution are a deadly mix for asthmatics and people vulnerable to heart problems, a study of hospital admissions has found.
New research has found that the incidence of heart attacks, strokes and respiratory problems skyrocket on days that are both hot and polluted.
The five-year study, published in the International Journal of Meteorology, is one of the first to examine how this "dangerous" environmental combination affects health.
"We've found a special relationship between heat and pollution and it's not a good one," said Professor Shilu Tong, a public health specialist at Queensland University of Technology.
"With the trend of climate change continuing, and more hot weather on the way, we have a timely warning of how it's affecting us."
Professor Tong and PhD student Cizao Ren correlated hospital admissions, temperatures and air-pollution levels across Greater Brisbane between 1996 and 2001.
Respiratory problems such as pneumonia and asthma usually improved over summer when temperatures rose above 25C.
But high levels of pollution appeared to ruin the benefits of warm weather by apparently exacerbating allergies.
"High air pollution negates the beneficial effects of higher temperatures on respiratory hospital admissions," Mr Ren said.
Admissions for strokes and heart attacks generally increased as the temperatures rose, but high pollution compounded the problem.
"More deaths occur when these two factors are both high," he said.
"But when we have high temperatures and low pollution, the effect of temperature is less strong on cardiovascular mortality."
The link between the factors is not yet understood but Mr Ren believed the physiological stress caused by high temperatures could make people more susceptible to air pollution.
He urged people with health problems to try to lower their exposure to air pollution on peak pollution days - generally Tuesdays, Wednesdays and Thursdays.
- AAP
