In the past year, her research team has published two studies showing clear effects from ozone and PM2.5 at or below the WHO-recommended limits. Such findings raise the stakes for the harm likely to be done by the pollution cocktails in China and elsewhere.
Kulmala, in his Nature article titled “China’s choking cocktail,” says we can expect “chains of chemical reactions” taking place among the multiple pollutants on Chinese smogs. Those reactions, he says, may have unexpected consequences that make conventional regulation of individual pollutants unpredictable and even counterproductive.
“Attempts to control one pollutant can increase the concentration of others,” he warned. For instance, controlling NOx emissions can sometimes result in a tenfold increase in ozone levels in summer, because while some NOx compounds create ozone, others destroy it.
Once pollutants are inhaled, there may be unexpected synergistic health effects, too, according to Joe Mauderly of the Lovelace Respiratory Research Institute in Albuquerque, New Mexico. The synergies may either accelerate or decelerate dangerous biochemical changes.
Researchers in the megacity of Guangzhou in southern China recently published data showing an apparent synergistic effect in the city between nitrogen dioxide (one type of NOx emission) from vehicles emissions and PM10 particulates from coal burning. When either of the pollutants were at high levels, there were more deaths in the city over the subsequent two days, especially cardiovascular deaths. But, most disturbingly, when both pollutants were at high levels, the increased death toll was more than twice as high as for one pollutant. In combination, they “mutually amplify the risk of mortality,” concluded the paper’s lead author, Yuzhou Gu of the Guangzhou Center for Disease Control and Prevention.
Article source: https://e360.yale.edu/features/how-a-toxic-cocktail-is-posing-a-troubling-health-risk-in-chinese-cities