When is it best to do vigorous outdoor exercises during the ground-level ozone season?
[Back to Top] It is safe on ozone action days to exercise in the morning, because ozone does not usually reach unhealthy levels until the afternoon when temperatures are the hottest. Morning is a good time for biking, walking, jogging or other types of strenuous outdoor activities. At high elevations in the mountains, ozone levels can remain high throughout the day and night during bad air events – so people should limit outdoor activities if they notice signs of problems such as coughing and breathing difficulty.
