The levels of particulate matter floating around thanks to the High Park fire reached the “unhealthy” category on Friday. According to Christopher Dann, public information officer for the Colorado Air Pollution Control Division, the whole Front Range is feeling the effects of the ravaging fire. So how, exactly, are you supposed to fit in your hour-long training run without coughing up a lung? We talked to Dann and pulmonologist Barry Make at National Jewish Hospital, to find out how to get outdoors without getting sick.

Watch your symptoms. Your body will tell you if it’s safe to be outdoors. If you’re 20 minutes into a bike ride and your eyes itch, your throat gets scratchy, and you begin to cough, turn around. The level of smoke isn’t safe. Luckily, Make points out that unless levels are really high, healthy people shouldn’t have any long-lasting negative effects to their lungs as long as they know when to stop.

Rely on sight and smell. Pick a fixed point five miles out. If the air’s clear, lace up your shoes. If you see haze or lose sight of the point, your area has enough smoke to affect sensitive groups like older adults, young kids, and those who suffer from asthma. If you smell smoke, that means it has settled down to the level of where you’re living and everyone will feel its effects, Dann says. In the last two cases, it may be wise to find a gym or fire up the treadmill.

Check the wind. “It’s not just about where the fire is, but what the prevailing winds are doing,” Make says. It may take some planning, but the further you can stay away from the fire and its smoke, the better. If the wind is blowing east, head west for your workout. If it’s blowing south, head north. The same goes for elevation. “Depending on the time of day, winds may blow down the valley where the smoke will settle, or reverse later and blow the smoke up mountains,” Dann says.

Take it easy. Save simple workouts for outside. “There’s a reason we say to avoid strenuous exercise,” says Make. “The faster you run or ride your bike, the harder and deeper you breathe, bringing more polluted air into your lungs.” Need another reason? There’s no reprieve—other than time—for that irritated throat feeling that comes with smoke inhalation.

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