Exercising in the Smoke

Adapted from previous articles by Theodore Ford, MD & Annika Landis 

Unfortunately, even though it is only June, many parts of the East and Midwest are already experiencing smokey days from wildfires burning in Canada. That means we need a quick reminder of some of the general guidelines for how to exercise safely in the smoke. For those who are unfamiliar, many athletes use an Air Quality Index (AQI) to determine whether the level of pollutants in the air is unsafe to breathe. AQI is a measure in micrograms per cubic meter of air of particles sized 2.5 microns and smaller (PM2.5) which are the most hazardous to health. An AQI under 50 is considered ‘healthy’ and training can proceed as normal. An AQI from 50-100 is typically safe for low intensity (and shorter duration) training but not for any high-intensity training like intervals or speeds or long over distance. Anything above 100 makes it unsafe to train outside at all. These are just guidelines, but generally being cautious is better than risking lung damage. 

I agree with what the federal government says on their smoke information website: All people in a smoky area (except firefighters or emergency personnel) should avoid strenuous work or exercise outdoors. They should avoid driving whenever possible. If driving is necessary, people should run the air conditioner on the "recycle" or re-circulate mode to avoid drawing smoky air into the car. Closing up a home by shutting windows and doors can give some protection from smoke. Most air conditioners are designed by default to re-circulate indoor air. Those systems that have both "outdoor air" and "re-circulate" settings need to be set on "re-circulate" during fire/smoke events to prevent smoke-laden air from being drawn into the building (note: this does not apply to HVAC systems in office and commercial buildings; see Appendix A). Once people have closed up the building in which they live, they should avoid strenuous activity, which can make them breathe harder and faster. 

https://oehha.ca.gov/media/downloads/public-information/document/wildfirev8.pdf

Pollution and wildfire smoke consists of tiny airborne particles and carbon monoxide, so exercising in the smoke is generally not a great idea. At rest we breath about 6-8 liters per minute (minute ventilation) and with exercise this can increase to as much as 8 times this amount or 50-60L/minute. Just breathing at rest in moderate to unhealthy smoke, is the equivalent of smoking 1.6 cigarettes per hour. Exercising would be like huffing 13 cigarettes per hour, or a pack of cigs in a 2-3 hour workout.  

If you can avoid going outside during smoky conditions, do so. Do not exercise in the smoke. 

Many athletes are still chomping at the bit to get outside. This becomes a question of mental health as many of us get somewhat irritable if we can't get outside for a workout. If you must exercise, then the answer is mitigation, that is, do so as safely as possible. Here is my recommendation as a physician and biomedical engineer. 

If you choose to exercise in the smoke, wear a tight fitting NIOSH approved respirator that filters out all the smoke particles. 

Lets dig deeper into that statement. The mask must have a good seal against your face in order to cover your nose and mouth and not allow any air to leak around the side, so that all of your inspired breaths are filtered through the filters. Exhaled breath is typically vented through a valve. If any air leaks around the face then the filter is not filtering and you are smoking cigarettes again. So shave off the beard, and check the mask fit. 

NIOSH is the National Institute for Occupational Safety and Health, part of the CDC. They certify the performance of masks used for filtration. So the crap that is hand-made, or a fashion accessory doesn't count. (these are only useful for blocking respiratory droplets to reduce COVID spread). The designations for these high quality filtration masks are N (not resistant to oil particulates) R (resistant to oil) and P (oil proof). Any of these are useful for breathing in smokey air. The next number is the percent of particles filtered out of the air by the mask material. 95%, 99%, or 99.97%. The test particles are 0.3 microns ( one thousandth of a millimeter). For reference, the pollution particles are 2.5 microns and smaller. Bacteria are about 1 micron and virus particles are approximately 0.1 micron ( but tiny viruses can ride on larger respiratory droplets). So N95 masks filter out 95% of particles 0.3 microns (and presumably larger) if there is a tight fit. Any of these filters when used properly should protect you from dangerous smoke and infectious particles. By the way, HEPA (high efficiency particulate air filters) filter out 99.97% of this size particle. 

What is a respirator? We have all seen the white masks with N95 on it. These are disposable. These usually don't create a tight seal so these will not serve our purposes of complete protection. Think of the silicone rubber mask with the filters on both sides , and straps around the head. These are respirator masks (half face elastomeric reusable air purifying respirator). You need the straps to hold the mask tightly against your face to ensure a good seal. Anything else is bullshit. Can't wear one of these? It is too uncomfortable? Then don't go outside for exercise. 

The half face masks cost about $20-40. I have found that instead of the cartridge filters that attach to the sides of these masks, P100 filters that look like pink fabric discs are light weight and less cumbersome. A pair of P100 filters cost $10-20. These filters are oil proof and filter out 100% of hazardous smoke particles. 

If you can tolerate 2 hours of exercise, sweating into a silicone rubber face mask, then these work great. I have been out in hazardous smoke conditions and I can't even smell the campfire. I have done mountain bike and cycle-cross races in the dust and, looking back, I wish I had worn one of these. I believe the most important safety issue is making sure that you are not excessively increasing the work of breathing. The flow of filtered inspired air should be unobstructed and easy. If it feels like you are sucking hard, change the filter or stop exercising. It is theoretically possible to cause lung injury from breathing hard against excessive resistance, including collapsed lung. The filter should be replaced if there is resistance to breathing through it. Breathing very hard increases the work of breathing and requires high flow rates, so I also recommend that the exercise intensity should be easy or moderate. NO HARD intervals. 

I want to emphasize that I am NOT saying that you should exercise in the smoke wearing a painter's filtration mask. What I am saying is that if you feel that you MUST exercise outside despite the smoke, then the only reasonable way to do so is to wear one of these filtration units. I don't recommend that you try this more than once a week. 

When we find ourselves not able to do training as usual, its time to think outside the box. Creativity is an often underused skill in a sport that benefits from consistency, but I think it is a crucial way to almost always make your training work for you in whatever context you may find yourself in. Adaptability is key. 

Often with smoke, you have to wait until the morning of to make a call on safety, which makes it hard to plan training in advance. Each day, you have to be willing to change your plan to reflect the conditions and often that means trading your long run in the mountains for a spin bike or erg. When this happens, my motivation to train plummets and I find it difficult to get excited about going to the gym and spending two hours on a spin bike.

A good equation for any unusual or unforeseen training circumstances is as follows:  

Reset + Reevaluate + Recharge = Adaptability  

Reset: 

• Take some additional time in the morning to re-plan your day makes a big difference in being able to bring energy and quality to that day of training. 

Reevaluate: 

• Can I make the workout shorter in order to maintain higher quality throughout?  
• Can I add variation like switching between a ski erg, spin bike, treadmill in order to stay engaged and work different muscle groups? 
• Can I come up with a unique set of intervals or speeds that I wouldn’t normally do? 
• If I end up not being able to train as many hours, can I use that time for better recovery, like stretching or yoga?  

Recharge: 

• Effective training on its own is mentally taxing, but adding the extra strain of uncertainty due to smoke (or other factors like travel, family events, injury, etc…) can start to wear you down. It is important to pay attention to when the scales start to tip because that is a good indication that it’s time to give your mind a break.

Adaptability like any other part of skiing, you have to train for. Using the summer months to experiment and practice responding to different situations, both of your own making (i.e. changing your breakfast, changing your warm up before a TT, etc…) or out of your control, (i.e. smoke) will make you an athlete that is not easily rattled and is ready no matter the context, to give their best effort.