Good morning, lungs. Let’s check the AQI (air quality index) before we check our Strava.



If checking the air quality has become part of your warm-up routine lately, you’re not alone. Between wildfire smoke, smog, and urban exhaust, outdoor athletes are facing a stealthy opponent: air pollution. And spoiler alert—it’s not just unpleasant. It’s performance-limiting, inflammation-boosting, and, in some cases, long-term lung damage–ing.





Why Athletes Are Especially at Risk


Let’s get real: your VO₂ max can’t out-train polluted air.


When you’re grinding through hill sprints or crushing tempo runs, your ventilation rate can skyrocket from a resting 500 L/hr to a whopping 6,000 L/hr (1). That means way more air—and more pollutants—are making their way into your lungs.



And if you're breathing through your mouth (you are), you’re bypassing your nose’s filtration system. Straight to the lungs, baby.




Confused about all the new jargon? Does size matter? Short answer, yes.



Welcome to Particle Size 101:

  • Particulate matter is a mixture of many microscopic chemicals both solid and liquid
  • Airborne smoke, soot, ozone, exhaust, dust, nitrogen dioxide (that's often what makes the city sky look redish)
  • Larger than 10um are not considered harmful since don’t get past your upper respiratory tract
  • Fine particles are smaller than 2.5um
  • Ultrafine particles are less than 0.1um
  • Fine and ultrafine are the most toxic because they can enter deep into the airways of the lungs. They carry toxic hitchhikers—ozone, NO₂, soot—that love setting off inflammatory cascades.





Performance Impacts Are Real—and Gendered


Real-world studies are tricky due to shifting particle concentrations and individual variability, but the results are sobering:

  • Cyclists exposed to traffic-based pollution showed airway inflammation and reduced lung function within hours (2)
  • Hikers and runners in ozone-heavy areas had declines in FEV1 and FVC—classic markers of airway restriction. And a greater ozone exposure history lead to more asthma and wheeze in hikers. (3)
  • Women may be more susceptible due to estrogen receptor interactions with pollutants (4) (5)



Let that sink in: your hormones might make you more sensitive to air pollution than your training buddy.




So... How Much Is Too Much?



Even “moderate” pollution levels can be too much. Lung function declines have been recorded at 60 parts per billion (ppb) of ozone—well within what some city days hit (6).




Smart Athlete Strategies to Breathe Easier

💊 Vitamin C 2000mg: Reduces oxidative stress and lung inflammation in asthma and exercise-induced asthma (7)(8), but more studies are needed.

🐟 Omega-3s: Shown to dampen pollution-induced inflammation (9).

💨 Train smart: Indoors when AQI is poor, and shift sessions to times when pollution is lowest (think early morning)

🧬 Address your baseline: Reduce systemic inflammation and support detox pathways (and yes, a naturopath can help with that 😉)




Final Lap

You train with science. Let’s recover with it, too. Your lungs, recovery, and performance all depend on it.

Check your local air quality before lacing up:

🇨🇦 Ontario AQI

🇺🇸 U.S. Ozone Monitoring


Note

  • in Canada parts per billion (PPB) are measured
  • in the USA it’s parts per million (PPM)
  • Conversion 1 PPM = 1000 ug/m3





References

  1. Air pollution, athletic health and performance at the Olympic Games. J Sports Med Phys Fitness. 2016 Jul-Aug;56(7-8):922-32. Epub 2015 Mar 19. Ken Fitch
  2. Respiratory health effects of ultrafine and fine particle exposure in cyclists. Occup Environ Med.2010 Feb;67(2):118-24. doi: 10.1136/oem.2009.046847. Epub 2009 Sep 22. Maciej Strak
  3. Effects of ozone and other pollutants on the pulmonary function of adult hikers. Environ Health Perspect 1998 Feb;106(2):93-9.S A Korrick
  4. Sex differences in the expression of lung inflammatory mediators in response to ozone. Amer J Physio: Lung Cellular and Molecular Physiology. Nov 15 2015. Noe Cabello
  5. The role of estrogen receptor β in fine particulate matter (PM2.5) organic extract-induced pulmonary inflammation in female and male mice. Research Article. Published: 18 April 2022. Volume 29, pages 60922–60932. Huaqi Guo
  6. Lung Function and Inflammatory Responses in Healthy Young Adults Exposed to 0.06 ppm Ozone for 6.6 Hours. Am J Respir Crit Care Med. 2011 Jan 7;183(9):1215–1221.Chong S Kim
  7. The effects of vitamin C on respiratory, allergic and immunological diseases: an experimental and clinical-based review. 27 February 2023. Mohammad Hossein Eshaghi Ghalibaf
  8. Vascular benefits of vitamin C supplementation against fine particulate air pollution in healthy adults: A double-blind randomised crossover trial.Ecotoxicol Environ Saf 2022 Aug:241:113735. doi: 10.1016/j.ecoenv.2022.113735. Epub 2022 Jun 8.Jingyi Ren
  9. Mechanistic insights into the health benefits of fish-oil supplementation against fine particulate matter air pollution: a randomized controlled trial. Environmental Health volume 21, Article number: 104 (2022). Lu Zhou