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.