Buzz
When the air quality is compromised—such as due to wildfire smoke—outdoor exercise is often not recommended. Let's examine why, and explore what you can do instead.
Exercise increases your breathing rate
Exercising during smoky conditions is particularly challenging because physical activity naturally leads to deeper breathing. The more intense your exercise, the greater the need for oxygen, and consequently, the more air you'll need to inhale to meet that demand.
Air pollution contains various harmful components, but one of the most concerning is PM2.5 particles, which are smaller than 2.5 microns. (In comparison, dust and pollen usually fall into the PM10 category, which is under 10 microns.) These tiny particles can penetrate deeper into the lungs. Smoke or polluted air with a high concentration of PM2.5 particles can irritate the eyes, nose, throat, and lungs, often leading to coughing and shortness of breath.
Indoor air is generally cleaner than the air outside.
When air quality deteriorates, it’s usually outdoor exercise that we’re advised to avoid. However, indoor air quality can also fluctuate.
Some homes—especially newer, more energy-efficient ones—are quite effective at keeping indoor air separate from outdoor pollution, while others might allow more air leakage. If you live in an older house or keep windows open regularly, you may have a significant amount of particulates indoors too. Closing windows, using appropriate vents for your air conditioning, and investing in an air purifier can help improve air quality.
This suggests that indoor exercise is generally preferable to outdoor exercise in terms of air quality, though if indoor air quality is poor enough, it can still irritate your lungs. This is a good opportunity to explore indoor workout options, whether through a YouTube video or using a bike trainer. On the most polluted days, however, it might be wise to simply take a rest day and wait for the air quality to improve.
How bad is the air quality to stop exercising?
There isn’t a simple yes or no answer to this, but here are some helpful guidelines.
If the air quality index (AQI) is 50 or lower, the benefits of exercise may still outweigh the pollution risks. A 2016 study, as discussed here in Outside, suggests that short exercise sessions are generally safe at this level. For further guidance, the Yolo-Solano Air Quality Management District in California provides a chart to help you determine what type of exercise is suitable for various AQI levels.
If the AQI is above 200, outdoor exercise is not recommended. Between 151 and 200 (“unhealthy for everyone”), outdoor activities should include plenty of rest periods, and it's better to move indoors if possible. For AQI levels between 100 and 150 (“unhealthy for sensitive groups”), short outdoor activities are acceptable, but team practices or workouts should be toned down in intensity. Below 100, the chart considers it a “great day to be outdoors.”
Be aware if you belong to a ‘sensitive group’
If you fall into one of these sensitive categories, the chart suggests keeping track of your symptoms as air quality worsens. Children under 12 and adults over 65 are considered part of these sensitive groups. Individuals with asthma, lung conditions, or those who are pregnant should be cautious and reduce outdoor exercise, even if others around them are managing fine.
Allergist and pulmonologist R. Sharon Chinthrajah told Medscape that she is adjusting medication and action plans for some patients, urging them to reach out if they experience increased breathing difficulties. If you have a lung condition or belong to another sensitive group, consulting with your doctor on how to manage the heightened health risks during wildfire season may be wise.
Air quality affects your health all day, not just during exercise. Spending time in clean air and wearing an N95 mask can help reduce the number of particulates you inhale. While cloth masks don’t provide the same level of protection as respirators, Chinthrajah mentioned to Medscape that they may still offer some benefit.
