Don’t Play With Fire: Key Facts About Wildfire Smoke & Particulate Matter

The severity of the recent fires in California can hardly be overstated. According to the Sacramento Bee, fires that began this past summer account for “five out of the six biggest wildfires in California history.” Together, these fires have burned an astounding 3.5 million acres, destroyed over 7000 structures, and resulted in dozens of lives lost. Over 17,000 firefighters are currently hard at work, trying to contain the blazes.

But while we rightly worry about burned natural areas or destroyed homes, there’s also been an increasing focus on air quality. That’s important, because wildfire smoke can prove extremely harmful—and can affect areas hundreds of miles from the blaze itself. If you’re confused about the makeup and impact of wildfire smoke, this post should help clear the air.

Firefighters before a blaze in California.
Firefighters combatting the LNU Lightning Complex fire (Source)

Where There’s Smoke

Wildfire smoke travels based on weather variables—changes in temperature, wind, water vapor, and precipitation. With the “right” combination of factors, smoke can travel hundreds, or even thousands, of miles from the initial fire. For instance, smoke from California was reported in both Hawaii and Ohio—a distance of over 4,000 miles. Even here, in New York City, I’ve heard anecdotal reports of an unusual haze.

The good news is that scientists are able to predict where smoke will end up before it arrives. Interestingly, this process doesn’t involve tracking actual smoke. Rather, it involves identifying the locations of various fires, and then applying a sophisticated model incorporating weather elements to predict its eventual destination. These models use color to show where smoke levels are expected to be particularly high:

An example of an NOAA Smoke model
An example of the NOAA smoke monitoring model (Source)

One of the best models, developed by the NOAA, is publicly available, so you can explore how smoke is affecting your area. A useful guide to operating the model has been written up here. It’s interesting and informative to see the relationship between weather patterns and smoke in real time.

However, understanding the location of wildfire smoke is not as simple as just looking at the map. It’s also necessary to understand that smoke isn’t distributed equally. Different particles naturally travel at different atmospheric levels, depending on their weight. “Near Surface Smoke” hovers within ~8 meters of the ground, and typically consists of heavier particles. “Vertically Integrated Smoke,” made up of lighter particles, can reach up to 25 kilometers into the atmosphere.

When evaluating this map or reading articles on smoke in your area, you should consider Near Surface Smoke levels, as that’s primarily the type of smoke you’ll be inhaling. But that’s not to say that Vertically Integrated Smoke isn’t important, however—it can impair air travel, block incoming sunlight, interfere with the natural climate, and even compromise solar energy production.

Given that, no matter our location or altitude, we are all increasingly affected by wildfire smoke, it’s worth asking: what exactly is wildfire smoke?

The Dirt on Wildfire Smoke

The question might seem obvious, but it’s actually fairly complex. Wildfire smoke is comprised of tiny particles from whatever material has burned to create it. While this includes vegetation—mostly trees, dry grass, and brush—it also includes burnt building materials. Chemically, these add up to “a mixture of carbon dioxide, water vapor, carbon monoxide, particles, hydrocarbons and other organic chemicals, nitrogen oxides, and trace minerals.”

Surprisingly, particles which are not attributable to the initial wildfire can be present in wildfire smoke! Particles have a natural tendency to attach themselves to other particles—sort of like how water droplets will merge together when they near one another. This means that high particulate matter levels can be present even when the largest particles have already left the air. For instance, ash, which we might instinctively expect to be a major component of wildfire smoke, doesn’t travel very far. Wildfire ash particles are heavy, meaning that they often fall quickly to earth. But other, smaller particles attach to less visible components of smoke. Because of this effect, the composition of the smoke changes depending on its distance from the initial blaze.

Given all these variables, it’s most useful to think about wildfire smoke in terms of particulate matter. Particulate matter, or “PM”, is defined as “the sum of all solid and liquid particles suspended in air, many of which are hazardous.” There are two major types present in wildfire smoke: PM10, and PM2.5. The numbers refer to the maximum size (in micrometers) of the particles described. As is discussed above, PM10 will be more common near the initial sight of the fire, with PM2.5 making up an increasing proportion of the smoke farther away from the epicenter.

Measuring Wildfire Smoke Levels

While the computer model mentioned earlier is one way to monitor smoke, there are different, more hyper-local methods. Using one of these methods is often preferable, because air quality can vary drastically even within small geographic areas. Perhaps the easiest way to estimate air quality is to use a visibility test, which works particles in the air reduce visibility over long distances. The following EPA chart is useful in employing such a test:

A table outlining how visibility and PM relate
The visibility test is particularly useful if you don’t have access to the internet (Source)

You can also look to services which utilize data from public monitoring stations. Temboo recently released an air quality monitoring dashboard for just this purpose! This dashboard provides information on PM2.5 and PM10 (as well as the EPA’s six criteria pollutants) for locations of your choice. It’s particularly useful because you can graph data, export results, and even sign up for daily AQ email updates via our free tool, The Daily Breather. Oftentimes, informative patterns emerge: for instance, air quality in my location worsens during rush hour.

Example Daily Breather email
Make checking your air quality a daily habit with The Daily Breather x Temboo!

If you require an even more accurate understanding of local particulate matter, you can use a PM sensor, like one of the ones mentioned in my previous post on air quality testing. Such sensors are often fairly inexpensive (at or under ~$300). And, if you use a Temboo compatible sensor, you can utilize all of Temboo’s data visualization and alert features (as outlined above). Whatever your preferred method, it’s important to monitor PM2.5 and PM10—particularly during fire season—because of the wide variety of health effects they cause.

Health Impacts

Smoke in San Francisco, showing the impact of wildfires
Wildfire smoke continues to blanket San Francisco (Source)

According to the EPA, all sizes of particulate matter can cause adverse health effects. But the most pernicious effects are actually caused by smaller particulate matter. That’s because smaller particles more easily enter your eyes, lungs, and bloodstream. When this occurs, people experience a variety of ailments, including palpitations, heart attacks, aggravated asthma, coughing, and eye irritation. The extent of these effects can worsen over time as people are exposed to more and more particulate matter. 

While everyone can be impacted by particulate matter, there are several populations who should take particular care to avoid it. The most obvious of these groups are people with lung conditions (like asthma, which affects 25 million Americans). For instance, during the 2007 California fire season, one study found that emergency room visits for asthma increased nearly 50%. And considering that 2007 was a milder fire season than 2020, one expects the impact to be even greater this year. It’s also worth noting that smokers, whether or not suffering from another lung condition, can be included in the population of those with lung conditions.

Another sensitive population is those with cardiovascular disease. According to the EPA, studies have linked particulate matter increases to “increased risks of heart attacks, cardiac arrhythmias, and other adverse effects in those with cardiovascular disease.” Sadly, over 125 million Americans suffer from a cardiovascular condition—meaning that just about half of people exposed to wildfire smoke will fall into this category alone. 

And, of course, all those who are more susceptible to adverse environmental factors should exercise caution. This includes pregnant people, young people, and elderly people. It also includes those suffering from preexisting conditions—and those who are sick. 

This last category is particularly important during the Covid-19 pandemic. There’s emerging evidence that pollution from the California fires can increase both the changes of getting sick and of dying from Covid-19, amplifying the already large problem of the disease itself. One study from Italy reported that “The infection rate tripled when particulate matter increased 250 percent, and mortality rates doubled when particulate matter increased 220 percent.” If you’re in a location affected by wildfire smoke, it’s more necessary than ever to follow good Covid-19 protocols.

Dealing with PM

It’s not always possible to avoid wildfire smoke, so it’s vital to know how to deal with it. First, it’s important to monitor particulate matter and air quality so that you can understand the current situation and respond to it. You can do this through a computer model, a local AQI report, or even a personal sensor.

It’s also useful to have an emergency preparedness kit in case you need to remain indoors for a long period of time; the EPA provides a page outlining what you can include in your kit. If you do have to venture outside, you should wear a mask that can filter out particulate matter, like an N95. As the CDC explains, the N95 was actually named as such because it can filter out over 95% of airborne particles. 

 Beyond these three key strategies, you should stay indoors, close windows, or even relocate to a Clean Air Shelter (if available). You should also try to minimize the other sources of particulate matter, which could worsen already bad air: things like smoking, burning wood or incense, or using a gas stove. Another surprising thing you can do to minimize exposure is avoid exercising. While exercise is normally great for the lungs, it also means that you inhale 4x as much, which is problematic if you’re breathing contaminated air. 

Finally, if you live in an area that’s likely to be affected by wildfire smoke, it’s prudent to invest in a system which can clean your air. Indoor air cleaners can remove particles from the air, significantly reducing health risks. While such cleaners can be expensive, and it can be confusing to figure out which one is right for your location, this guide on indoor air cleaners in the home can help. Such an air cleaner can be a wise investment.


Unfortunately, it seems unlikely that wildfire smoke and particulate matter will become less of a problem in the future. Climate change causes a variety of environmental shifts, most of which increase the likelihood of wildfire: earlier snowmelt, drier soil, prolonged summers, and hotter daily temperatures. The effects of these factors can be easily seen by looking at the number of acres burned every year in California:

Graph showing climate change's impact in increasing fires.
Wildfires have a steadily worsening impact over time (Source)

This means that it’s important, especially now, to have a good understanding of wildfire smoke and particulate matter. By monitoring PM, developing plans to deal with wildfire smoke, and taking proper precautions, you can ensure your health and safety—and that of your family, friends, and community. 

At Temboo, we want to help you do just that. If you’re interested in PM monitoring solutions—whether at your home, workplace, or somewhere else—please don’t hesitate to reach out

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