The Exchange

Commentary and Observations from
the Medical Front Lines

Protecting Patients From Unsafe Air Quality

Protecting Patients From Unsafe Air Quality

With all of the fires raging in California, many other areas far from them are experiencing poor air quality too. Poor air quality can have both long- and short-term adverse effects on patient health.

Wildfire smoke is comprised of a mixture of gaseous pollutants (eg, carbon monoxide), hazardous air pollutants, polycyclic aromatic hydrocarbons, water vapor, and particle pollution. Particle pollution represents a main component of wildfire smoke and is the principal public health threat.

Individuals at greater risk of adverse health effects from wildfire smoke include those with cardiovascular or respiratory disease, older adults, children under 18 years of age, pregnant women, outdoor workers, and those of lower socioeconomic status.

The US Environmental Protection Agency has a great resource page for wildfires that includes strategies to reduce exposure to poor air quality both indoors and outdoors. For example, staying indoors is typically better than being outdoors when outdoor air quality is poor, as particle levels and activity levels are generally lower indoors. To reduce smoke in your vehicle while driving, closing the windows and vents is recommended. In addition, running your car's air conditioner in recirculate mode will reduce air intake from outside.

If you go outdoors when smoke levels are in the unhealthy ranges, consider wearing a respirator. It is recommended that people use a "particulate respirator" N95 mask. Other masks such as paint masks, dust masks, or surgical masks will not prevent smoke inhalation.

The most common advisory issued during a smoke episode is to stay indoors. The effectiveness of this strategy depends on how well a building limits smoke from entering, and on efforts to minimize indoor pollution sources. Regardless, staying indoors will provide some protection from smoke, especially in a tightly closed, air-conditioned home in which the air conditioner recirculates indoor air. Generally, newer homes keep ambient air pollution out more effectively than older homes. Staying inside with the doors and windows closed can reduce the entry of outdoor air into homes—in some cases by 33% or more.

During periods of high smoke levels, patients whose homes have fresh air intake should close the intake or set the system to recirculate mode. The central heating/cooling system filter can effectively reduce indoor particle concentrations when the system is operating. If the system has a standard fiberglass filter, upgrading to a filter rated MERV13 or higher can be especially important during smoky periods to effectively remove fine particle pollution in the indoor air.

Lastly, during a wildfire smoke event, portable air cleaners fitted with high efficiency filters may reduce indoor particle concentrations by as much as 45%. Furthermore, portables can be operated continuously at a lower cost compared to the continuous operation of a central system.

It is imperative that we educate our patients on the health effects of poor air quality and the ways they can reduce their risk.

There is a free course available to healthcare professionals to learn about air quality and its effects on health. is a great site to check your local air quality to determine if the air near you is good, moderate, unhealthy, or even hazardous.

  • Fisk WJ, Chan WR. Health benefits and costs of filtration interventions that reduce indoor exposure to PM2.5 during wildfires. Indoor Air. 2017;27:191-204.
  • Howard-Reed C, Wallace LA, Ott WR. The effect of opening windows on air change rates in two homes. J Air Waste Manag Assoc. 2002;52:147-159.

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Filed under: Public Health, Pulmonary Medicine

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