Study Extreme Weather, Air Pollution, and Stroke

The research question:

How does extreme weather affect air pollution in California?

What is the association between air pollution and stroke?

Although weather patterns vary across California, the occurrence of extreme weather—unusual, unseasonal and/or severe weather such as drought and wildfires—has increased over the last decade. This project will examine how these extreme weather events affect air pollution, and whether the associated changes in air pollution affect risk of stroke and other cardiovascular diseases such as myocardial infarctions or heart attacks.

Meet the researcher: Dr. Sophia Wang, Ph.D., is a molecular epidemiologist at City of Hope, and has expertise in how cancer develops and how individuals that get cancer fare after their treatment. She completed her education and training at the Massachusetts Institute of Technology (MIT) and at the Johns Hopkins Bloomberg School of Public Health.

To learn more about Dr. Wang and her other research projects, please click here.

What makes this project unique: Particulate matter (PM), also called particulate pollution, is the term used to describe the mixture of solid particles and liquid droplets found in the air. PM is often categorized by size; PM2.5 are small particles with diameters of 2.5 micrometers or smaller—that’s thirty times smaller than the width of a single human hair.1

Because these particles are small enough to be inhaled, they pose a risk to individuals’ health. The largest source of human exposure to PM2.5 is typically from traffic emissions. Previous research has shown a link between PM2.5 exposure and risk of stroke and overall mortality. Separate, independent research has also demonstrated that the risk of stroke increases with age. In women, the risk for stroke rises post-menopause.

This project is unique because it will evaluate risk factors that directly affect California Teachers Study participants: increased exposure to extreme weather, as wildfires become more common and severe across the state; exposure to PM2.5 pollution; and the risk of a health outcome—stroke— that is more common among an aging population. In addition to identifying whether extreme weather events influence stroke and cardiovascular disease risk, this project will be the first to delineate between long-term exposures (such as from traffic emissions) and acute exposures due to extreme weather events.

The questionnaire answers used: For this project, the researcher team will be using participant responses to past CTS questionnaires, including self-reported information on health conditions like asthma, family history of cardiovascular disease (CVD), prior CVD diagnosis, and participant use of various medications.

1EPA. Particulate Matter (PM) Basics. Available at