Smithsonian Magazine Special Report

Awareness of exposure, high-quality masks and air filters can help protect you from the dangerous pollutants in the smoke

When engineer Devabhaktuni Srikrishna learned of the Covid-19 preparation plan at his children's school in San Francisco, he knew it was short-sighted-the school planned to circulate outdoor air through the classroom to improve ventilation and hope to reduce the spread of the virus.

Srikrishna, the founder of Patient Know How, said: “This is a good strategy when you can breathe the air from the outdoors, but when wildfires may occur and you don’t want to breathe the air from the outdoors, they cannot solve the fall problem,” he said. A website that scores the fit and filtering quality of the mask.

Instead, he and a parent team raised funds to provide teachers with portable air filters that can purify the air from infectious virus aerosols and toxic wildfire smoke pollutants.

Last year, western communities faced the double crisis of a deadly wildfire season and the Covid-19 pandemic. This summer, the number of Covid-19 cases rose again, partly because of the spread of highly contagious virus variants. After years of drought and untimely heat waves, wildfires have also become intense. Piracy fires swept Oregon and burned a large area of ​​land larger than Los Angeles. Some plumes have become so large that they have begun to create their own weather patterns.

As the smog spreads thousands of miles to the east coast, air pollution caused by wildfires may no longer be a regional problem.

"This is becoming a chronic exposure," said Tarik Benmarhnia, an environmental health scientist at the University of California, San Diego. "I want to say that [wildfire] was once a very extreme event, and it may happen every few years. We can't talk about it anymore."

Fortunately, you can take steps to protect yourself and your loved ones from wildfire smoke. Here are the steps you need to take to ensure your safety.

Wildfire smoke is composed of various gases and particles with different chemical compositions. Although many of these ingredients may be toxic, the most harmful are the tiny particles called PM2.5. The diameter of these particles is 2.5 microns, which is about 1/30 the width of a human hair.

Due to their small size, these particles can be inhaled deep into the lungs and sometimes enter the bloodstream. There, they can cause serious damage to vital organs of the body, causing cardiovascular, respiratory and even nervous system problems. Research has linked PM2.5 exposure to asthma, stroke, eczema, certain cancers, etc.

Such particles appear in air pollution from transportation, industry, and agriculture. But those found in wildfire smoke seem to be much more harmful to the body. In a study published in Nature Communications in March, Benmarhnia's team found that PM2.5 in wildfire smoke can increase the number of people hospitalized with respiratory problems by 10% compared to PM2.5 from other sources.

When a large amount of PM2.5 accumulates in the air, gray haze sometimes appears. At other times, the particulate matter remains largely invisible. This is why it is important to check the air quality in your area.

The Air Quality Index is an indicator established by the Environmental Protection Agency, ranging from 0 to 500, of which 500 is the most polluted. It accounts for five major air pollutants: ground-level ozone, particulate pollution (including PM2.5), carbon monoxide, sulfur dioxide, and nitrogen dioxide. The scale is color-coded to help members of sensitive groups and the public quickly understand the degree of air pollution. Sensitive groups include children, the elderly, people with respiratory or heart disease, pregnant women, and outdoor workers who have been exposed to smoke for a long time.

When the air quality index is in the green, yellow, or orange zone, which is 150 or lower, it is usually safe outdoors. At 150 or higher-in the red, purple, and maroon areas-most people are susceptible to negative health effects, and those who are particularly sensitive to air pollution should be extra careful. At these levels, the EPA recommends staying indoors as much as possible, wearing a mask when unable to do so, and restricting strenuous outdoor activities such as exercise.

To know the real-time air quality index near you, you can visit AirNow.gov, which is a website in cooperation with the EPA, the National Oceanic and Atmospheric Administration, the National Park Service, NASA and others. The site uses research-grade instruments to report accurate air quality index, but these instruments may be far apart.

Another website called Purple Air collects detailed pictures of the location of polluted air from household air quality monitors across the United States.

When the air quality is particularly poor, Marina Vance, an engineer at the University of Colorado Boulder, said it is best to avoid going out together. When you must be outdoors, finding a high-filter mask is the key.

Just like protecting yourself and others from Covid-19, Vance said that any mask is better than no mask. But unlike Covid-19, harmful particles in wildfire smoke can easily penetrate cloth coverings and weasels through the gap between the mask and the human face.

"In the context of wildfires, one potentially dangerous thing is that when people are not protected, they feel that they are protected," Vance said. "When there are wildfires and air pollution, they will go out, they will wear cloth masks with low filtration efficiency, and have this misguided sense of security."

Srikrishna said that the most important factor is how closely the mask fits your face. If there is a leak, no mask can effectively block contaminants or virus particles. If you wear glasses and fog when you put on a mask, it means that the seal is not tight enough.

The rating of a mask is based on how many particles can be filtered out when worn correctly. For example, N95 mask can block 95% of particles, while P99 can filter 99%.

"This is what these n95 masks are designed for-to help maintain breathability while providing good filtration. Whether you're talking about Covid or wildfire, it works," Srikrishna said.

Srikrishna's favorite mask uses a semi-flexible N95 filter with a strong rubber silicone seal on the edge. Other versions have a sturdy plastic frame and round, replaceable filters on each side of the mouth. For individuals who are accustomed to wearing disposable surgical masks, some companies make straps that fit on the top to form a strong enough seal to classify the product as N95.

N95 and other high-filter masks are particularly effective because they carry an electrostatic charge. Just like the socks will stick together when they are pulled out of the dryer, small particles will stick to the electrostatic properties of the mask.

Although the Covid-19 pandemic and wildfire season demand may cause the supply of disposable N95 masks to dry up, Srikrishna said there are other highly rated respirators to choose from.

"Just like buying shoes, there are many different types and many manufacturers," Srikrishna said. "You have to find a product that suits you and provides aerosol filtration."

Staying indoors on a hazy day can significantly protect you from wildfire smoke. Nevertheless, polluted air can still leak into buildings, increasing health risks, especially for people with weakened immune functions or pre-existing diseases. Vance recommends closing all doors and windows and using air-conditioning for ventilation to close possible passages (if any). In some extreme conditions, please consider sticking plastic sheets around the windows to ensure a better seal.

To purify the air in your home or building, you can buy a variety of different portable air purifiers. Many of them work by using fans to circulate air through high-efficiency particulate air (HEPA) filters. The HEPA filter that has been in use since World War II is still the standard filtration technology. These filters are composed of many randomly arranged fibers that mechanically absorb tiny particles in the air, such as pollen, dirt, dust, and some bacteria and viruses.

"Keep it simple and don't be fancy," Vance said. "There are some portable air purifiers that use ionization technology, electrostatic precipitation, and all kinds of bells and whistles. To be honest, all you really need is a filter."

Srikrishna emphasized that when purchasing an air filter, individuals should consider the size of the room they want to purify. Since square feet calculations are non-linear, he said that individuals often mistakenly underestimate how much filtering capacity they need. For example, if you buy a filter for a 15 x 15 foot (225 square foot) room, you need four to properly clean a 30 x 30 foot (900 square foot) room.

These filters can be used to clean air pollution and SARS-CoV-2 (the virus that causes Covid-19) in the air. Srikrishna said: “When you use it in shared settings for Covid prevention, you need to turn it on as much as possible,” and pointed out that most filters are designed to detect particles. If you keep the automatic settings, you won’t catch virus-carrying Aerosol. "It's a very simple thing, but it makes everything different. Otherwise, it can't do anything."

If you have heating, ventilation, and air conditioning (HVAC) devices in your home, you can also install filters to purify the air circulating in the building. Choose a HEPA filter with a MERV rating of 13 or higher. Even on mild days when the air conditioner is off, Vance recommends running the central fan with the filter in place for additional cleaning.

For those who find it too expensive to buy a portable air filter or to run an air conditioner, researchers are testing the efficacy of a DIY solution that involves connecting a MERV 13 or HEPA filter to a standard box fan to create some filtered ventilation.

Reduce other forms of pollution

On a personal level, there is nothing you can do to prevent or stop active wildfires. As the West is struggling to deal with smog, Benmania said that it is important to consider the unfair impact of air pollution on the community.

"Everyone is exposed to [wildfire smoke], but we didn't start from the same place," he said. "Some people are already vulnerable because they live in contaminated areas from other sources, in very hot environments, or in specific occupations, which may expose them to other problems and pressures that may not be related to wildfire smoke."

In order to limit these additional sources of pollution, please consider driving less, not using wood stoves and restricting the use of gas-powered equipment when the air quality is poor. For individuals whose occupations require them to be outdoors most of the day, such as agricultural workers and construction workers, wearing protective clothing and well-fitting masks can limit skin and lung exposure.

No matter how you choose to protect yourself from air pollution, it's best to plan immediately before wildfires become more violent.

"Planning in advance is a smart idea," Vance said. "When wildfires hit your area, these products tend to disappear from the shelves."

Editor's note, August 11, 2021: Due to a mathematical error, this article initially misreported the number of air filters used to clean a 30 x 30 foot room. The correct number is four.

Claire Bugos is a reporter and former printing intern for Smithsonian Magazine. She recently graduated from Northwestern University, majoring in journalism and history.

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