Discussion: Air quality

Thanks for the nice summary. Sounds like we might need our own PurpleAir sensor some day.
The air in Yellowknife was in the 450 range *before* it got bad!

Interesting study - thanks! In contrast to AQHI, it considers the long term impact of inhaling PM2.5 rather than the acute effects. That's one of my big problems with AQHI. This study looks at long-term mortality.

Just so I've got it here in simple language for future reference:

The study notes that different types of runs have different impacts. The harder you work (basically the harder you breathe), the lower the PM2.5 level you need for the run to benefit your health compared to staying at home. (Which is the base level comparison they make.)

"The health benefit assessment revealed a tipping point of 65 μg/m3 (40% VO2max), 55 μg/m3 (60% VO2max), and 45 μg/m3 (80% VO2max and 85% VO2max), respectively, for a 60-min run.

"Furthermore, the assessment revealed a break-even point of 120 μg/m3 (40% VO2max), 95 μg/m3 (60% VO2max), 85 μg/m3 (80% VO2max), and 80 μg/m3 (85% VO2max), respectively, for a 60-min run."

The Aussie standards addressed different types of effort too, which is important for people like us.

As CO said, the tipping point is the PM2.5 level at which you do not receive additional health benefits by doing the run. (Arguably, there may be fitness benefits if you're preparing for a race but the run won't help you live longer.)

The break-even point is the PM2.5 level at which the run actively causes harm, i.e. it could shorten your life.

You can only get approximate values from the graphs in the study but the other variable is running time. If you run more than 60 minutes, the level of PM2.5 needs to be lower to achieve a health benefit compared to staying at home. You can't get exact numbers from the graphs but it appears that the tipping point for a 2-hr run at 60% VO2 Max is in the 35-40 μg/m3 range, compared to 55 μg/m3 for a 1-hr run at the same effort. And for a 30-min run at 60% VO2 Max, the tipping point is 80 μg/m3.

They also allude to other activities with lower impact, such as walking and cycling - activities where you may be able to breathe through your nose at a respiration rate closer to normal.

So there's a lot of good info there to guide decisions. As PM2.5 rises:
- Lower your intensity.
- Shorten your run.
- Consider other forms of exercise that don't make you breathe as hard.
- Exercise indoors, assuming you have better air quality there.

That’s crazy that the air quality in Yellowknife was already that bad before it got really bad! We had air quality readings of up to 450 in Canmore on our worst day or two earlier this summer and I wouldn’t even open the door for a second for fear of letting some of that air in.

Thanks for the summary and the additional interpretations, Bash :). I too will refer back to it.

It's too bad we need to learn about this. It's as much fun as learning about ticks.