When is the best time to exercise if there is high air pollution?

Exercising at any time is better than not exercising at all. There are numerous health benefits to exercising regularly, such as improved heart health, increased strength, and increased endurance. Most people exercise when it is most convenient for their schedule, so they are often at the mercy of the time of day they choose to be active.

If you routinely work out, you've probably heard various pieces of advice about the best times to fit your workouts in. You've probably also heard for a long time that exercising first thing in the morning is best. Moreover, experts say that people are very happy to exercise in the morning as the first task completed in a day so that the mind becomes more focused. However, what if you have to exercise in the midst of bad air pollution conditions? Will this affect our body on a more personal level? 

Early morning air quality is the worst

In fact, the air quality in the atmosphere is very poor from early evening until early morning. This is caused by a temperature inversion, which is a phenomenon caused by the flow of air masses in the atmosphere, resulting in temperature differences in the atmosphere. This inversion will prevent air from rising upwards, accumulating air pollution near the earth's surface and making air pollution on Earth's surface worsens. The temperature inversion will fade as the air temperature rises during the day.

Inhaling pollutants poses a special risk to athletes

Exercise is essential for good health, both physically and mentally. But the advantages of outdoor exercise may be diminished by potential health risks associated with air pollution. The air pollution level, a person’s health status, and the length and intensity of the exercise are all important to consider. During exercise, a greater proportion of air is inhaled through the mouth, effectively bypassing the normal nasal mechanisms for filtration of large particles and soluble vapors. Aside from that, a higher airflow velocity also transports pollutants deeper into the respiratory tract. Furthermore, pulmonary diffusion capacity has been shown to increase with exercise, suggesting that pollutant gas diffusion increases with exercise.

Nine of the 16 papers reviewed found that exercising outside in polluted air has short-term (temporary) health consequences, with lung function impairments being the most common. Another study discovered that people who did moderate to high-intensity exercise outside in low or high levels of air pollution had fewer health effects than those who did low-intensity exercise. The study suggests that for people with pre-existing conditions such as respiratory or cardiovascular disease, even low-intensity activities such as walking may exacerbate the negative effects of air pollution.

The best time of day to exercise is whenever you can do it consistently

With only 24 hours in a day, finding exercise time can be hard these days along with uncertain air quality. In fact, you can exercise whenever you want as long as the air quality is healthy. According to research conducted in 367 Chinese cities, evening outdoor exercise is preferable to morning exercise because it results in less inhalation exposure to PM2.5. However, air pollution varies spatially and temporally within a day and season so knowing the best time to exercise outside is important for avoiding potential health risks from inhaling particulates such as PM2.5

Nafas continues to support you by adding an Air Quality Alerts feature to our app. This feature will help you figure out the best times for you to exercise in healthy air quality. 

It's also very easy to do! Alerts can be set by choosing "Set Air Quality Alert" on any location, which opens the settings menu. In settings, you can choose whether to set Air Quality Alerts by time or AQI.

Once the feature is turned on, you will always receive notifications about air quality easily. You will find it easier to determine an exercise schedule and know the things that must be prepared before starting outdoor activities.

We will add additional features from time to time to help you avoid air pollution. If you want to suggest something, please contact us here - [email protected].


Can air pollution negate the health benefits of cycling and walking? (2016). Preventive Medicine, 87, 233–236. https://doi.org/10.1016/j.ypmed.2016.02.002

​​Ni, X.-F., Peng, S.-C., & Wang, J.-Z. (2019). Is Morning or Evening Better for Outdoor Exercise? An Evaluation Based on Nationwide PM2.5 Data in China. Aerosol and Air Quality Research, 19(9), 2093–2099. https://doi.org/10.4209/aaqr.2019.07.0362

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