Login | October 03, 2024
Pollutants and exercise
PETE GLADDEN
Pete’s World
Published: September 23, 2024
Ever struggled to make a decision about going outdoors for your workout amidst poor air quality levels?
Well, this year and last I’ve gone through that mental wrestling match, and I have to admit that there’s been an occasion or two when I did my outdoor workout despite bad air quality forecasts.
And I have to say that on each and every one of those days I disregarded the air quality forecasts, I did so with a tsunami of questions swirling around in my head.
Just how long and how hard should I go?
How often can I get away with this?
And how about wearing one of my unused, COVID-era N-95 masks, would that make a big difference?
So these questions led me to a recent study written by Dr. Michael Koehle, MD, PhD, and assistant professor in both the School of Kinesiology and the Division of Sports Medicine in the Department of Family Practice at the University of British Columbia.
His paper, “Physiological impacts of atmospheric pollution: Effects of environmental air pollution on exercise,” was published in the April 12, 2024 edition of Physiological Reports.
In this study Koehle explored four key questions concerning outdoor exercising amidst poor air quality levels:
1. What is the influence of exercise intensity
2. What are the effects of pre-exposure to air pollutants
3. Can you acclimate to air pollution
4. Does mask use while exercising reduce the effects of the pollutants.
Here are his findings.
Q1. For me, this is the biggest question: Is high intensity dangerous when exercising in poor air quality environments? So based on the very few studies examining this angle - which only used diesel exhaust as the air pollutant - he found that, “the effect of exercise intensity on dose and health and performance effects requires more investigation, but recent work in diesel exhaust shows surprisingly minimal acute health and performance effects and no worsening in higher intensity.” He did caution that these results should not be extrapolated to include pollutants such as those from wildfires.
Q2. Here he questioned whether resting exposure to air pollution had any effect on individuals down the road when they exercised in a clean air environment. To answer this question he cited two past studies that used diesel air pollutant exposure for individuals at rest who subsequently went on to exercise in a clean air environment. Two findings were gleaned from these studies. First, heart rates were higher when diesel pollutant preexposure was administered prior to the clean air exercise session than when clean air preexposure was administered prior to a clean air exercise session. And second, diesel pre-exposure induced an absence of exercise-induced bronchodilation, a common physiological occurrence when exercising.
Q3. With respect to pollutant acclimatization and exercise, Koehle found that most of the research regarding this topic involved ground-level ozone. And there appears to be various lines of evidence that supports the supposition that the body can adapt to ozone in the context of exercise. What’s more, these studies suggest that athletes can train to acclimate to this particular pollutant in the same way they train to acclimate to heat.
Q4. The author found little in the way of studies that addressed masking while working out. The most useful study examining this issue was a double-blinded study performed in 2018, and it concluded that mask use resulted in a 48% to 74% efficiency rate in terms of reducing the particle count for a small group of healthy adults who walked for two hours in the streets of Beijing during heavy levels of air pollution. Unfortunately he found no studies concerning mask use at exercise intensities above a casual walking intensity.
As you can see, considerably more research is needed to fully understand the physiological effects of exercising amidst poor air quality levels, especially with regard to intensity, duration and frequency of exercise.
Thus, for the time being it’s still best to defer to the AQI (Air Quality Index: https://www.airnow.gov/aqi/aqi-basics/) before you undertake that outdoor workout.
This index details six color coded categories of air pollution which describe the air quality in our area, who might be affected, and steps we can take to reduce our exposure.
It’s also used for air quality forecasts and air quality reporting.
My main takeaway here involves the mask use which I’ll definitely employ when outdoor workout passion overrules indoor common sense.