Poor Air Quality and Asthma: Should You Wear a Mask?
During a recent encounter with poor air quality (which doesn’t happen much locally), the Weather Network app on my phone advised against wearing masks in such weather. This left me perplexed—after all, aren’t masks supposed to protect against at least some of the particulate matter that causes air quality to be poor?
Less than a week later, I can’t find the verbiage provided in the app, despite checking for cities still under poor air quality advisories. This leads me to believe it’s possible that the combination of a heat warning and a special air quality statement/warning may be the cause of this specific app-shared warning. Someone on Instagram also told me the same.
Of course, then I started wondering why the heck they’d advise not to wear masks. Uselessness? Hazard? General lack of evidence? I went to Google and the journals to understand why my (very brief) stint wearing my Vogmask with N95 filter outdoors may have been contraindicated.
Gathering the data on face masks for poor air quality
It turns out, in the last 10 years, there is simply not much data supporting the use of face masks (also known as respirators or respirator masks) for filtering the poor quality air. A January 2015 article states “Limited evidence suggests that the use of respirators may be effective in some circumstances.”1
However, rarely, if ever, is limited evidence able to be conclusive. We need multiple, long-term studies to determine such things conclusively. Further, an Australian Family Physician published article notes:
“Further research on the role of face masks in managing the public health impacts of episodes of bushfire smoke pollution is needed. Two studies from communities affected by wildfire smoke in the United States have evaluated face masks. One of the studies, which was conducted in an indigenous community, did not find that mask use reduced symptoms or health care attendances, and attributed this to inconsistent use, poor fit testing, and variation in mask effectiveness.”
—Bushfires and human health in a changing environment (2009)2
Consider air mask quality
The same study notes that improper fit of masks worn by non-health care provider (HCP) consumers may negatively affect performance of the masks, which in some cases—like if fit properly—can filter as much as 90% of pollutant from the air 1—HCPs actually go for a test where their face is measured to ensure they wear the correct mask size. In healthy participants, walking while wearing the mask in poor air quality for 24 hours led to decreased heart rate and decreased blood pressure compared to those not wearing, despite the added work of breathing with the resistance of the mask.1 This speaks to the impacts of air pollution on cardiovascular health.
Less stark evidence is available for asthma or other lung diseases. In my search for, "evidence for wearing mask air pollution asthma” on both Google and Google Scholar, I came up with only the following statement directly referencing asthma and use of masks: “When air quality is very poor, levels of
[…] pollutants are so high that they can act directly on the lungs of people with asthma. […]
There is no good evidence that wearing a face mask will be helpful.”4
So, masks likely are not going to hurt, and they may even help in general—though they may, for those of us with asthma, make breathing feel more difficult. But simply, there’s not enough evidence to conclude or even suggest masks are helpful for those of us with asthma on high air pollution days.
Should you wear a mask?
Generally, it would appear from the scholarly data you should not invest significant money into a mask for air pollution. Consumer reports offer the same suggestions, turning the research into actionable and understandable recommendations. From mainstream media, The Guardian notes “face masks may not be the answer to our problems,” affirming “If [a mask] fits well, then breathing through a mask is not easy,” and “Wearing a mask could, therefore, pose a problem for those who already have breathing or heart difficulties.” 5
CTV News Health states the lack of effectiveness but notes if you feel more comfortable wearing a mask, don’t go for the cheapest option and “choose the best one you can and look for one marketed to workplaces”. 6The Conversation also considers the role of placebo effect: "The main reason that these findings should be interpreted cautiously is that participants were aware that they were breathing filtered air. 7 You simply can’t study a mask that is to go on a person’s face without them knowing, which of itself can skew the results! Finally, individual masks will offer differing results dependent on fit, filter efficacy 8, and even facial hair. 5
The best choice is to talk to your doctor before making any changes—as always—including wearing a mask. They may recommend you wear a mask in certain situations (such as when dusting if you have dust mite allergy), or at times you are exposed to smoke or other specific air quality problems.
I opted out of wearing a mask for asthma
I opted not to wear my Vogmask (with N95 filter) when walking outdoors due to the heat and difficulty in breathing it can cause, and I kept it off at the bus stop until someone lit a cigarette in my vicinity. I did find it helped when I was still, but I would not have been able to tolerate it when in motion. Although, let’s be honest, it could have been the placebo effect of taking action.
I figured though, that since I purchased a mask in the spring, I might as well try it. Fortunately, my thought process was backed by the fact that generally, mask-wearing seems to do no harm, even if it may not be necessary. I still had significant symptoms the next day, so just like the research, my own results are inconclusive, too.
Do you ever wear a mask to prevent asthma symptoms, and why or why not? Did your doctor recommend one? Let us know in the comments.
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