Concurrent Heat Waves, Air Pollution Exacerbate Negative Health Effects of Each

“The weather factors that drive heat waves also contribute to intensified surface ozone and air pollution episodes,” said UCI professor of Earth system science Michael J. Prather, co-author of the study, published this week in Proceedings of the National Academy of Sciences. “These extreme, multiday events tend to cluster and overlap, worsening the health impacts beyond the sum of their individual effects.”

Heat waves cause widespread discomfort and can be deadly for vulnerable individuals, while surface ozone and air pollution are linked to premature death from heart disease, stroke and lung ailments.

A heat wave and pollution episode struck the eastern portion of the United States and Canada in late June of 2005. Observations show the concurrence of high surface ozone, an abundance of fine particulate matter and scorching temperatures.

Credit: Jordan Schnell / Princeton University

Prather’s group made the findings after examining 15 years of surface observations (1999-2013) for the eastern United States and Canada. The researchers overlaid a grid of one-degree-square segments onto a map of the region and analyzed the recorded levels of surface ozone, amounts of fine particulate matter (pollution) and maximum temperatures between April and September for each roughly 69-by-69-mile section of the map. This allowed them to construct a climatological picture of the duration, coincidence and overlap of each of these factors.