This past month has marked the end of summer and the beginning of autumn for many of us around the world. 

📷 James Wheeler

This transition has been a particularly complicated one this year with a return to school and work (or just life in general) in the midst of a global pandemic, unprecedented wildfires on the west coast (USA), and extreme weather—all of which affect the air we breathe.

📷 Craig Adderley

During this time we have been focused on doing what we can to provide information and advice to people struggling to find fresh air on the west coast of North America as wildfire season continues. 

📷 AP / Eric Risberg

Working with AccuWeather and the Los Angeles Times, we have compiled some of the most frequently asked questions related to air quality and wildfires with the hope that it will be a useful resource during pollution peaks, or if your region should be affected by a wildfire or other major air pollution event.

Read on the the Q&A…

Where has the worst air quality been observed in Oregon and California?

The worst levels (over 800+ Plume AQI) were recorded in Yosemite National Park, Portland and San Francisco – far exceeding levels recorded in the recent past – for example California: 500+ Plume AQI at the Palmdale monitoring station (north of LA) during december 2017. 

So far, have the fires on the US west coast been worse than previous years?

5 of the 10 largest fires in California history are currently burning which is of course an unprecedented situation. Very unhealthy levels of AQ are recorded in California and Oregon. The states are literally covered by smoke – half of Oregon monitoring stations have recorded Airpocalypse levels earlier this week! Smoke is transported across continental US by dominant winds and even further – it has been observed over Switzerland! However, health impacts are mostly limited to CA/OR and neighbour states (Idaho and Washington) as the smoke is lifted up while travelling east.

What’s the best way to use Flow during wildfire season?

During a pollution peak, like in the case of a wildfire, the air quality indoors is generally much better than outside. During the early-September spike in smoke on the West-coast of the USA, the Silicon Valley YMCA used their Flows to test the air indoors, and out in order to determine what programs they would run that day, and where.

At the same time, individuals in the region and as far north as British Columbia, Canada were using theis Flows to alternately test the air in their homes and outdoors to determine when it would be safe to open the windows and air things out. 

Understanding the AQI thresholds is key when making tough decisions during an air quality crisis. When the AQI drops from very high to moderate, certain outdoor activities become possible. These changes can be very localised depending on where you are located, the topography of your surroundings and the local winds. This is when Flow becomes invaluable when compared to a local monitoring station that may be kilometers away.

How does air pollution from wildfire smoke compare to other types of air pollution? For example, smog that develops in some cities in China? 

The main difference between ‘normal’ urban air pollution and that created by a wildfire is: (1) intensity: a huge amount of PMs and gases are released in a very short period of time. Consequences are poor visibility and import health impact. (2) the nature of the pollutants: much more particles in the wildfire smoke (this is why it is ‘visible’) and also much more VOCs (as mentioned in the previous bullet)

Our own Dr. Boris Quennehen studied the composition of anthropogenic and forest fire pollution plumes transported from mid-latitudes to the Arctic. His work shows that processes affecting particle size and concentration are still active after several days of transport in the atmosphere.

Dr. Quennehen: Like any combustion process, wildfires emit a mixture of particulate matter (PM) and gases. A 2013 study showed that the PM chemical composition and gas types / concentrations varies depending on the materials burning. In particular, forest fires emit significantly more pollutants, mostly because they last longer. However, urban fires are more likely to emit a higher percentage of toxic gases due to plastic or mineral oil burning. 

In the case of a wildfire, a lot of dead and standing trees get burned up, along with other biomass like dry grasses. Even variations of wood and how it is burning can make a difference. For example, a recent study of wildfire smoke in California found that smoke coming from a smouldering, smoky fire with little visible flame is more damaging than smoke coming from a really bright, intense flaming fire.

How does breathing in the air pollution from wildfire smoke compare to smoking a cigarette?

According to a 2015  study, recent wildfire pollution levels were roughly the smoking 25 cigarettes / day.

What health effects can people experience after breathing in air pollution from the wildfire smoke?

Wildfire smoke exposure can have very real health consequences. The most common health risks associated with smoke exposure are found within our lungs, the major organ of the respiratory system. Smoke exposure can lead to difficulty with breathing, including coughing, runny nose, bronchitis, wheezing and exacerbation of chronic diseases such as asthma and chronic obstructive pulmonary disease (COPD).

Our community member and contributor, Dr. Jonathan Tan, says: “In my experience working in hospitals around the world, smoke exposure during wildfire disasters also increases emergency department hospitalisations and need for medications. This has an impact across almost all aspects of patient care. 

It is also important to consider that some populations are more affected by smoke exposure. 

Health effects may be exacerbated if you:

  • Have heart or lung disease (e.g., congestive heart failure, angina, chronic obstructive
  • pulmonary disease, emphysema, asthma)
  • Are an older adult (especially if you have heart or lung disease)
  • Are pregnant.
  • Are a smoker.
  • Are a child. Smoke can be more harmful to children because their respiratory systems are still developing, they breathe in more air than adults, and they are more likely to be active outside.
  • Are involved in strenuous outdoor work or outdoor sports.

In these vulnerable groups, the risk of illness and even death can be much higher than for healthy adults. In addition to respiratory disease, wildfire smoke exposure has been associated with risks to the cardiovascular system, the eyes, the neurologic system and adverse mental health outcomes.“ 

Many people are already wearing many different types of face coverings when outside due to COVID-19. Is there a specific type of face mask that people should wear when outside due to the poor air quality from the wildfires?

To help protect against wildfire smoke, wear at least an FFP2 mask or higher. 

The non-surgical masks commonly recommended as part of COVID-19 strategies to reduce transmission are worn to protect others in the event the wearer is infected, rather than to protect the wearer. 

To complicate the situation, anti-pollution masks (FFP2 and above) commonly have valves to help let air out and make breathing easier. Unfortunately, valves render the mask virtually useless in preventing the transmission of viruses – because it is designed to let air out (along with whatever else might be in that air). It would be best to choose an FFP2+ mask without valves.

Is it ok to run the Air Conditioner in wildfire smoke?

Long answer: It depends what kind of air conditioner and filter you have. In your case, (and it’s a pretty common scenario) the AC unit is drawing air in from outside and cooling it in the process. The unit then vents back out into the wide world. Most ACs, window mount or otherwise, have some sort of filter. Just like a mask for your face, the filter is a ‘mask’ for your AC, and catches varying degrees of pollutants in the process of pulling outside air inside. There are a ton of different types of filtration – from the basic fibrous mesh that catches particulate matter, electrostatic, systems, active carbon (for gaseous pollutants), and so on. All of this to say, in a wildfire situation, the air in your house is very likely to be cleaner than the air outside. 

The nutshell: If you are going to be drawing dirty air in with an AC, you’ll want to be confident the type of filter you have can handle it. I would err on the side of caution if you don’t know about the filter. 

Is the air better by the beach?

Unfortunately, living by the beach doesn’t offer any special protections from wildfire smoke. Considering the beach and the urban landscape, we could consider the distance from busy streets as a potential benefit, as well as a lack of tall buildings making corridors that can trap pollution. However, in wildfire circumstances, the situation is so radical and the plume of smoke so big, the normal gains from local winds and proximity to other sources of pollution are virtually obliterated.

If you have any other questions about air quality, don’t be shy, you can reach out to us in the comments section below. We’ll do our best to answer them all.

Join the conversation! 4 Comments

  1. Thank you!

    Air quality has certainly been a challenge during the last month.

    My flow is been a constant companion.

    In fact,
    I think that the Flow is a wonderful gift for my two sons-in-law.


  2. Such a helpful read! Like mentioned by you, wildfire smoke can have serious impact on health. That is why having an air quality monitor can be a great idea. If the PM 2.5 levels rise above 151, it can be a good idea to wear a mask.


  3. […] into 2021, we’re all still processing the incredible events of the past year, culminating with a brutal wildfire season in North America, Western USA in particular, that smashed all air quality […]


  4. Thank you so much for this article. I find i suffer from severe migraines & sinusitis during times of year when wood burning & grilling are popular. It has greatly influenced my ability to be outside. I have resorted to using face masks, prior to Covid19 for better air quality & sometimes use a complete nose plug for swimming. I even have disposable nasal filters to help if i have to work (next to a busy restaurant with heavy cooking exhaust). I wish more of the masses realized that they negatively impact others around them & air quality in general with their decision to burn things in unnecessary situations. Most of the time i cannot be outside any longer than to grab mail & go immediately back inside. It’s very limiting. I value clean breathing air & do all i can to promote knowledge of its precious part in our lives & overall health.



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We're here to help you understand what you breathe and take meaningful action against air pollution.


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