Answer: F. All of the above

Large forest fires are 5 times more frequent today than 50 years ago. This has sparked interest in the adverse effects of exposure to wildfire smoke and particulate matter (PM).1 In addition to having similar toxic and carcinogenic substances as those found in cigarette smoke, wildfire smoke has a mixture of solid particles and liquid droplets. These are measured as PM and reported as the size of the particles.

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During the Sonoma-Napa wildfires, 24-hour exposure of fine particles in the San Francisco Bay area exceeded 200 mg per cubic meter. That is nearly 6 times the upper threshold set by the Environmental Protection Agency of no more than 35-mg per cubic meter of particles ≤2.5 mm in size (PM2.5).1 Short-term exposure to elevated concentrations of PM2.5 has been associated with increased risk for acute respiratory, cardiovascular, and neurologic outcomes.1,2

All of these adverse events have been associated with both acute and chronic exposure to fine particles from wildfire smoke. One study found that a 9-mg per cubic meter increase in exposure during 2 days was associated with an approximately 7% higher risk for out-of-hospital cardiac arrest, with a 4.5% increased risk on the day of the exposure.2

This patient with risk factors for cardiovascular disease should be advised to stay indoors with his windows and doors closed and the air conditioner set to recycle the internal air rather than bring smoky air in from the outside.1 Further, he should upgrade to high-efficiency particulate air filters. He should be advised to avoid going outdoors for prolonged periods of time.1 If he had moderate to severe respiratory or cardiovascular disease, then it might be beneficial to recommend an N95 or N100 mask when he goes outside and that, if possible, he should relocate to a region with better air quality.1

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  1. Balmes JR. Where there’s wildfire, there’s smoke [published online January 31, 2018]. N Engl J Med. doi:10.1056/NEJMp1716846
  2. Haikerwal A, Akram M, Del Monaco A, et al. Impact of fine particulate matter (PM2.5) exposure during wildfires on cardiovascular health outcomes. J Am Heart Assoc. 2015;4:e001653.