“I thought morning air was the polluted one”: why summer ozone peaks at 6 pm is a warning runners need to take seriously

'I thought morning air was the polluted one': why summer ozone peaks at 6 pm is a warning runners need to take seriously

Most runners assume morning air is polluted, but the chemistry tells a different story. Ground-level ozone peaks in early evening—not rush hour—creating a hidden threat for summer athletes. Learn why your evening tempo run might be sabotaging your performance and how to adjust your schedule.

The Hidden Morning Trap: Why 6 a.m. Runs During Heatwaves Might Be More Dangerous Than You Think

The Hidden Morning Trap: Why 6 a.m. Runs During Heatwaves Might Be More Dangerous Than You Think

You thought 6 a.m. was the safest time to run during a heatwave. A sports medicine consultant’s air quality chart revealed the truth: overnight ozone doesn’t disappear—it lingers, making “clean” morning air far more polluted than you assumed. Here’s what you need to know before your next heat-season workout.