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In the past, thunderstorms, heat waves, or snowstorms may have derailed your outdoor training plans, forcing you to come up with a plan B. But now there’s a new environmental scourge to add to that list: poor air quality.

Unfortunately, climate change is worsening air quality across the country, thanks to heat, drought, and wildfires that contribute higher levels of ozone and particle pollution. Though air quality has improved overall in the past 50 years, the 2023 American Lung Association “State of the Air” report indicates that more than one in three Americans currently live in places with unhealthy air.

While reduced air quality impacts everyone, outdoor athletes, like runners, cyclists, and hikers, are particularly susceptible to sucking in lungfuls of polluted air.

Exercising hard outdoors simply exposes you to greater levels of pollution compared to the person who is just walking or sitting outside, says Paul Kriegler, RD, CPT, director of nutrition product development at Life Time. “Heavy exertion causes dramatic increases in ventilation rate and volumes — how much air we bring into our lungs — so anything that increases ventilation could increase exposure to any particulate substances in the air.”

While humans are equipped with built-in filtering systems (from our nose hairs to our lungs) to deal with junky stuff in the air, fine particles from pollution — including from wildfire smoke — can cross into the bloodstream, triggering inflammation and impairing blood vessel function, explains Kriegler. Exposure to poor air quality could lead to increased risk of breathing problems, lung damage, asthma attacks, heart attacks, and stroke.

Check out these tips for determining whether it’s safe to exercise in unhealthy air, how to protect yourself when you do, and how to take your workouts inside without sacrificing the quality of your training.

How can I know if it’s safe to exercise outside?

When you have an outdoor workout planned, consider these factors:

  • Do you see smoke or haze? Can you smell smoke? These are “dead giveaways” to reschedule or relocate a hard workout, says Kriegler.
  • If you wear a fitness tracker that provides a performance indicator such as heart-rate variability (HRV), use that info to guide you during your workout. “Anytime I see a negative performance indication such as lower-than-usual HRV, I pay extra close attention to how hard I push that day,” says Kriegler.
  • Zero in on how you’re feeling. If you’re feeling sluggish, if you have a headache, or if you’re struggling more than usual, consider decreasing your pace or intensity or even stopping your workout. “The last thing you need to do is push yourself harder when the conditions are unfavorable,” Kriegler says.
  • Look at the Air Quality Index (AQI) from gov, which offers activity guidance based on ozone and particle pollution in your ZIP code. (Many weather apps report the AQI.) When air quality is good, the AQI will be flagged with the color green — meaning it’s a great day to be active outside. Meanwhile, the color yellow indicates that sensitive groups, like those with asthma, should take precautions. The colors red and purple denote higher levels of ozone and particle pollution and signal the importance of decreasing the duration or intensity of your workout — or skipping it altogether, if you’re in a more vulnerable group.

Can I make it safer to do an outdoor workout on a high-pollution day?

Natural environments often have better air quality than urban and suburban areas. So, depending on where you live, you could seek out green and blue spaces — for example, in a forest or near a lake or an ocean. Check the AQI at parks, trails, and beaches near you to see if any of them have better air quality than your immediate neighborhood.

Seek out green and blue spaces — for example, in a forest or near a lake or an ocean.

You can also sport an N95 mask or breathe only through your nose — two methods for filtering some (though not all) particles. While both approaches are safe for most people during lower-intensity activity, such as a leisurely walk or bike ride, they’re not ideal solutions during vigorous exercise if you’re not accustomed to them. Wearing a facemask during vigorous exercise may result in more labored breathing; though research doesn’t show that it affects oxygenation levels, difficulty breathing can result in increased rate of perceived exertion, fatigue, and even dizziness. And while nasal breathing is associated with improved blood-oxygen saturation and athletic performance, it is a skill like any other; jumping straight into nose-only breathing during a hard workout may make you feel breathless and increase exertion rates. If you want to adopt working out with a mask or breathing only through your nose, get comfortable during lighter, lower-intensity effort first. If you want to engage in a long duration or higher-intensity workout but don’t feel comfortable breathing through a mask or your nose yet, you may be better off amending your plan, if possible.

So, if I have to switch up my training plan, what’s the best approach?

That depends on what you’re training for, where you are in your training season, and what type of workout you have planned, says running and triathlon coach Mike Thomson, CSCS, USATF, a Life Time personal trainer in Overland Park, Kansas. For example, the further out you are from a race, the more leeway you have to modify or skip a workout. When you are four to six weeks from a race or event, however, each workout becomes more important, he says.

When you have a hard or long workout planned on a poor-air-quality day, you’re best off doing a cross-training or mobility workout instead to support your overall training — and moving your planned workout to the next day.

“One thing that’s important is to give yourself grace,” Thomson says. “We get all worked up in our head that we have to do this or that. But at the end of the day, an off- or skipped workout won’t change that much.”

However, if poor air quality lingers and doesn’t improve, move your training indoors and do your best on the treadmill or on the bike, says Thomson. It’s not ideal — especially for endurance and sprint training geared to a specific outdoor event — but it will support your fitness without sacrificing your health. In the long run, that’s the most sustainable and beneficial approach that can still support your goals.

“One thing that’s important is to give yourself grace,” Thomson says. “We get all worked up in our head that we have to do this or that. But at the end of the day, an off- or skipped workout won’t change that much.”

Does exercising outdoors on a high-pollution day negate the benefits of exercise?

The short answer is that although poor air quality may not actually negate the benefits of exercise, it almost certainly impacts your training by undermining performance.

The long answer? Well, research on this topic is still developing. A meta-analysis of 25 studies published in Preventive Medicine in 2020 concluded that moderate or intense exercise on high-air-pollution days may actually counteract the short-term negative effects of air pollution in healthy people (though not in more vulnerable groups). Paradoxically, low-intensity exercise amplifies these risks for everyone — and especially for those with pre-existing conditions, such as COPD. The researchers noted, however, that the studies examined were done under variable conditions and had inconsistent results.

A 2022 systematic review published in the International Journal of Environmental Research and Public Health, of seven studies that looked at the impact of heart health and exercising in air pollution, concluded that “the beneficial effects of outdoor PA [physical activity] are reduced when the exercise/PA is performed in an outdoor polluted environment.” Another study concluded that high amounts of exercise in highly polluted environments is harmful for heart health, though maintaining regular physical activity outside on low- or moderate-air-quality days was more beneficial than decreasing physical activity.

Despite the as-yet-inconclusive science, it’s likely that you might not feel on top of your game if you’re working out on a high-pollution day — and that’s a critical consideration during training.

A combination of increased inflammation and an inability to perform your best “would make trying to train ‘well’ a waste of effort, in my opinion,” says Kriegler. “Some inflammation created from a proper training stimulus is good, but potentially toxic inflammation has virtually zero upside.”

Poor air quality will certainly affect your workout, says Kriegler. Polluted air impairs your oxygen uptake, or VO2 max (an objective measure of the volume of oxygen that your body can utilize at any one time), so exercise may feel harder than normal, he says.

As a result, you may find it’s more difficult to hit the speed or intensity you’re aiming for and you may notice your heart rate is higher than normal. In the short term, he says, you might experience headaches, fatigue, cough, itchy eyes, and excess mucus production after the training session.

In the end, a combination of increased inflammation and an inability to perform your best “would make trying to train ‘well’ a waste of effort, in my opinion,” says Kriegler. “Some inflammation created from a proper training stimulus is good, but potentially toxic inflammation has virtually zero upside.”

Is there anything I can do nutritionally to support my lung health?

Eating a balanced diet can help minimize inflammation, says Kriegler. This includes a good amount of protein, fiber, antioxidant-rich produce, and healthy fats, such as extra-virgin olive oil, avocado, and grassfed butter.

In addition, Kriegler recommends omega-3 fatty acids. “Optimizing omega-3 fatty acid status would also help the body respond to inflammatory stressors, like air pollution, in a healthier way and has been shown to be helpful for respiratory function in those with chronic lung conditions, like asthma and COPD,” he says. Try to eat omega-3-rich fish like salmon and sardines, and consider a high-quality omega-3 supplement. Other helpful supplements that buoy respiratory health include N-Acetylcysteine, L-citrulline, and beetroot powder, as well as vitamins A and D.

“If you’re routinely exposed to toxins and can’t change it — like you run in an urban environment with poorer air quality — these are some of the first things I’d try to make your body as resilient as possible,” Kriegler says.

For more nutrition tips to support lung health and immunity, check out this article.

Jessica Migala

Jessica Migala is a writer specializing in health, nutrition, fitness, and beauty.

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