Please see The Sports Digest: Exdercise to exhaustin in heated ozone is a formula for death of and Athlete, http://www.thesportdigest.com/archive/article/exercising-exhaustion-heated-ozone-formula-death-athlete
Synergism is an interaction of discrete agents (as drugs), or conditions (as weather) such that the total effect is greater than the sum of the individual effects.
Example Climate Synergism: Dangerous Heat Index + Air Pollution (Ozone) = Death
“Particulates, ozone and smog coupled with extreme temperatures form a more dangerous health threat than these problems would be for each of these individually, researchers have found.
“The combined threat is apparent in both hot and cold ends of the temperature spectrum.
Scientists have long understood that air pollution is a serious health threat. The World Health Organization reported that in 2012, 1 in 8 deaths worldwide stemmed from air pollution.
“However, researchers are still mapping out the combined effects of air quality and climate.
“Most studies focus on one or the other,” said Alexandra Schneider, a senior scientist and team leader at Helmholtz Zentrum München, a federal health research institution in Germany.
“The study on pollution showed that ozone, which tends to form on hotter days, changes the risk profile of heat stress. However, particulate matter didn’t seem to have any impacts on the links between temperature and deaths.
“Reasons, though, remain unclear. The mechanisms linking temperature, pollution and death remain murky. “There are several hypotheses, and nothing is really 100 percent clear,” Schneider said.
[Air Pollution and Extreme Weather Combine to Kill, Researchers find a mix of pollution and extreme temperatures can be deadly, Sep 3, 2014 by Umair Irfan, Scientific American]