“I can see and smell the smoke in the air again today. Is it healthy to exercise in it or not?”

Whether that voice is the one in your head, or the voice of a family member or friend, the question is an important one.

These issues have arisen for many athletes with the increase in wildfires in North America and elsewhere in 2020, wildfires exacerbated by severe drought conditions in many parts of this continent.

In the second week of August, California recorded over ten thousand lightning strikes in a 72 hour period (as reported on August 20, 2020, by earthobservatory.nasa.gov). That led to hundreds of fires in that state, earning them the dubious distinction of having the “worst air quality in the world” for the previous day. In addition, the two fires seventy miles north of my home were barely contained, contributing enormous amounts of smoke while becoming two of the three largest fires in Colorado’s history. Far worse yet, by the middle of September, California had three million acres burned, and five of the twenty largest fires in state history were simultaneously burning (San Francisco Chronicle, 9-11-20). Oregon and Washington had one million acres burn in a single 48-hour period (NW Interagency Coordination Center in Portland, 9-11-20). Oregon alone had half a million people under evacuation orders.

And three weeks previously, I had wanted to take a run in the mountains near my town if the air quality was not going to hurt me. Embarrassingly self-absorbed regarding my own valley’s air quality, it appears.

And yet, amidst the tragic losses of forests, lives, and homes, each of us needs to have a means of knowing when our regional air quality is appropriate for a kid to ride a bike to school, for a senior citizen to be gardening outdoors, and for an immunocompromised patient to leave their home for groceries.

On the aforementioned August 19th here in my hometown of Montrose, Colorado, many friends, acquaintances, and patients reported the new onset of headaches, eye irritation, throat irritability, and/or low motivation and mild depression from the smoke. Checking the US Environmental Protection Agency’s Air Quality Index (AQI) that evening revealed that we had been experiencing several hours of Red/Unhealthy conditions. Does this mean “Unhealthy” to open the window if you have COPD, or “Unhealthy” to take a long run outdoors, or somewhere in between?

By the next morning, the AQI had eased somewhat to Orange/Unhealthy-for-Sensitive-Groups, but ash was visibly falling onto cars and homes in a neighboring valley, though it was forty miles from the nearest large fire. Two days after that “bad air day,” a running buddy texted me about a possible opportunity to run up the fourteener (4,282 meters elevation) named Handies Peak in a neighboring county. We could leave for it early the next morning, only if air quality improved overnight. We agreed by phone that, at 5 a.m. Sunday morning, we would each independently evaluate the most current readings from the weather site noaa.gov, as well as the AQI.

Only then would we decide whether or not to drive into the mountains to go run those steep three to four hours at altitude. Time to look at the AQI colors. We can trust the colors on the AQI, although a variety of reliable sources describe the meaning of each color ranking differently. For instance, look at the CDC/EPA chart below. Specifically, note the advice for the Purple/Very Unhealthy category.

I find the latter chart is more helpful, but would not the use of those decimals, micrometers, and ppm possibly deter the average citizen? Yes, it is thought, and therefore the CDC/EPA chart instead defines these zones around an arbitrarily assigned index “value” of 100, as seen in the prior chart. They have chosen to place 100 on the border between Yellow and Orange. This attempts to make the AQI more user-friendly for the broader populace.

I contacted the Utah Department of Environmental Quality about this difference in chart design, and Bowen Call of that entity confirmed that “There is significant confusion between actual values and the AQI values.” Just trust the colors, instead.

Notably, an even more simplistic scale is sometimes mentioned by authorities during popular press interviews, based solely on current visibility with the naked eye. If visibility is limited to five miles, vulnerable populations should take precautions to avoid exposure. At three miles, “vulnerables” should remain indoors and the healthy population should take precautions. If one mile, everyone should stay inside.

So, are we running long and high tomorrow morning, or not? Pursuing your own decision on versions of that question, you will come upon the US Forest Service and their Air Resource Advisor, the title for whom they describe as “a new category of technical specialist.” This Advisor is deployed specifically to communicate about the fire smoke conditions of a single, particular national forest. Their site is rather straightforward to navigate, and with practice at reading them, their reports have a higher level of detail, more hourly advice, and also forecasting for the day to come. Fire incident management personnel, high school coaches, and race directors are three types of users who may well desire this depth of detail. Cue on the word “outlooks” on their menus to more rapidly get to your localized forecasts.

A balanced decision regarding “go/no go” should prompt one to evaluate the breakeven point between deconditioning due to enforced inactivity from staying indoors for filtered air, versus outdoor aerobic activity benefits in air quality that is less than ideal. Though beyond the scope of this article, research has found, at least in the low quality city air situations studied, the use of cycling or walking is more healthful than driving an automobile up to a certain breakeven point; see this study in the journal Preventive Medicine.

 “What does the science say,” don’t we all find ourselves asking often in 2020? To decide whether the proposed run would be fulfilling or would be folly, I then studied the original research article in Wilderness & Environmental Medicine, Wagner and Brandley’s “Exercise in Thermal Inversions: PM2.5 Air Pollution Effects on Pulmonary Function and Aerobic Performance.” Within the conclusion section, they stated that “Young, healthy adults felt more respiratory distress running a 3200 m time trial on a day with elevated PM2.5 compared to a low PM2.5 day. However, there were no significant differences in running time” or in other tests of pulmonary function and exercise performance, which tests they deemed to be too imprecise to detect impact “by acute exposures of moderate amounts of PM2.5.”

So, did the air quality allow for a mountain run that August day, or not?

As it turned out, because our targeted morning’s sunrise AQI showed merely Yellow/Moderate for our valley, combined with a clean breeze from the direction where no fires existed, led to us deciding to go up the mountain. After having run up it, each of us was heading down from it before noon, as per smart travel strategies above timberline, to avoid lightning risks.

Although our clinical “study” had just n=2, neither runner subjectively experienced any ill effects after completing our run that day.

On one further practical point, exceedingly worse air quality is affecting millions of people in these recent few weeks, many of whose homes contain neither central air conditioning with filtration, nor costly HEPA filtration units. From a USFS website that is listed as still “under construction,” print-ready handouts are now accessible, as well as a Montana state link for easily assembling a very efficient DIY home air filter for about $40 cost in materials.

The US Bureau of Land Management employs about 3,000 wildland firefighters each year, and the US Forest Service another 10,000. Praise and thanks go to the many thousands of men and women working on our fire crews, and those in every country. In a decidedly somber tone, empathy and aid need to go to all those who are currently losing so much to these wildfires, especially in that we are not yet at the midpoint of a typical California fire season.