Canadian wildfires spread smoke throughout US

According to the Canadian Interagency Forest Fire Center, there are more than 400 wildfires actively burning in Canada, and more than 200 of them are burning out of control.

Bill Blair, Canada's minister of public safety, said at a news conference an estimated 26,000 people throughout the country have been evacuated.

"The images that we have seen so far this season are some of the most severe ever witnessed in Canada," he said.

According to AccuWeather, an area of low pressure hovering offshore and an area of high pressure over Canada have led a northerly flow of air to funnel the smoke from the wildfires into the United States, causing air quality issues throughout the country.

The Environmental Protection Agency (EPA) tracks air quality with its air quality index (AQI). An AQI of 0 to 50 is considered "good" air quality while 51 to 100 is considered "moderate." If the AQI is between 151 and 300, the EPA recommends everyone reduce or avoid intense outdoor activities, and an AQI between 301 and 500 is considered "hazardous."

As of Wednesday, New York City had an AQI over 400, and IQAir, a technology company that tracks air quality and pollution, said New York's air quality was among the worst in the world Tuesday night.

Meanwhile, Richmond, Virginia; Philadelphia; Baltimore; and Washington, D.C. all had AQIs of at least 160 as of Wednesday.

Why wildfire smoke is dangerous

The main health concern from wildfire smoke comes from very small particulates in the air that are smaller than 2.5 microns in diameter, commonly referred to as PM 2.5s.

"It's essentially the same stuff that you get from the campfire or in your fireplace, just on a much larger scale," said Peter DeCarlo, an associate professor of environmental health and engineering at Johns Hopkins Whiting School of Engineering. "Basically, it's these tiny microscopic particles about 100 times smaller than the width of our hair, made up of chemicals that get into our lungs and then get deposited into the rest of our bodies."

Health experts warned that breathing the fog can be as damaging as smoking 22 cigarettes a day.

Breathing in unhealthy levels of smoke and other pollutants can increase a person's risk of developing different lung and heart conditions, according to the EPA, and it can exacerbate pre-existing lung and heart conditions as well as trigger asthma and heart attacks.

"PM 2.5 can get into our mucus membranes and deeper into our lungs," said Sameer Khanijo, a pulmonologist at Northwell Health. "What makes them more dangerous for people with an underlying condition is that these particles are small enough that they don't get filtered out by our hair or cilia. They can get deeper into the lungs and cause reactive airway disease."

Aida Capo, a pulmonologist at Hackensack Meridian Health, said Wednesday she's seen an influx of patients because of the poor air quality.

"It's an almost immediate effect," Capo said. "If you're outside for any length of time, your symptoms can start and can worsen quickly."

According to Purvi Parikh, an allergist and immunologist at the Allergy & Asthma Network, smoke can especially be dangerous for pregnant women because they typically have diminished lung capacities. In addition, a study published in March found that smoke exposure during the first and second trimesters was associated with gestational diabetes.

DeCarlo added that PM 2.5 levels can affect other parts of the body aside from the lungs. "We associate respiratory conditions with air quality problems, but the reality is that it impacts our hearts and our brains and other body systems," he said. "Those chemicals that we breathe in will deposit in our lungs, and then from our lungs via our blood, travel to all other parts of the body."

How to protect yourself

Experts say there are multiple things you can do to better protect yourself from wildfire smoke.

1. Wear a mask or respirator

Wearing a high-quality, well-fitting mask or respirator can be effective at filtering our PM 2.5s. N95 and KN95 masks, as well as high-quality P100 respirators, offer a high level of protection, but cloth and paper masks offer very little protection against PM 2.5s.

2. Use an air filter

In areas with central air conditioning, using a high efficiency filter with a MERV rating of at least 13 can filter out a significant amount of pollution from the air. Similarly, HEPA filters are highly effective at cleaning the air in small spaces.

Experts also recommend you keep your windows closed, close any fresh-air intakes on air conditioners and in cars, and consider identifying a "clean room" in your home that has a little exposure to outside air as possible.

3. Pay close attention to air quality

"Don't let your eyes be the sole deciding factor" to determining air quality, said Panagis Galiatsatos, a pulmonary and critical care medicine physician at Johns Hopkins Medicine. You can monitor local AQI levels at EPA's website AirNow.gov.

If air quality is poor, you should stay inside as much as possible, according to Samantha Green, a family physician at Unity Health Toronto. If air quality is moderate and you have underlying health conditions, you may want to still be cautious and minimize your time outside.

"These toxins — if you can avoid them, avoid them," Galiatsatos said. "Staying at home, windows closed, that would be the most ideal situation."

If you do have to go outside, don't exercise or perform strenuous activity, said Laura Corlin, an assistant professor at Tufts University School of Medicine, and wear a tightfitting mask.

4. Limit your time with large groups

According to Francesca Dominici, a professor of biostatistics, population, and data science at the Harvard T.H. Chan School of Public Health, our immune systems are less effective after we've been exposed to high levels of fine particulate matter in the air.

That means, if you're immunocompromised, you may want to limit the amount of unmasked indoor time you spend with large groups, as you may be less able to fight off a potential virus.

5. Pay close attention to your health

Be sure to pay close attention to how you're feeling. People with underlying respiratory conditions, like asthma or chronic bronchitis, should watch out for exacerbated symptoms like difficulty breathing or intense coughing, Dominici said. If you're experiencing worse symptoms, you should contact your doctor.

In addition, Dominici recommended paying close attention to babies and young children to ensure they're not struggling to breathe or coughing excessively. If a child has asthma, parents may want to contact their child's doctor to see if their medication should be altered. (Parker, STAT, 6/7; Knutson, Axios, 6/7; Jimenez et al., New York Times, 6/6; Blum, New York Times, 6/7; Rodriguez, USA Today, 6/7; Lovelace Jr./Chow, NBC News, 6/6; Cueto, STAT, 6/7; Fiore, MedPage Today, 6/7; Potter/Alexander, Daily Mail, 6/7)

We know that climate change is a public health problem — and now, health care leaders are getting a better understanding of how their own organizations are contributing to the problem. Radio Advisory's Rachel Woods sat down with Advisory Board's  Miles Cottier  to discuss the state of climate change and why healthcare leaders shouldn't wait for government action to start making progress. Read a lightly edited excerpt and listen to the full episode below.