Smoke from Canadian wildfires triggered air quality alerts in more than a dozen U.S. states on Wednesday, with health officials warning people in sensitive groups, such as children, elderly or those with respiratory conditions to limit their time outdoors or stay inside.

Yahoo News spoke with health experts who explained how wildfire smoke affects your health, what you can do to protect yourself and how long the effects from the thick orange haze blanketing a large part of the country will last.

How do I check the air quality in my area?

“The U.S. Air Quality Index is getting a lot of media attention right now, but it is really fantastic,” says Dr. Brady Scott, a fellow at the American Association for Respiratory Care. “Because you can just plug in your zip code and kind of understand the air quality is where you’re at. If it’s green or yellow, it’s OK for most individuals. When it’s orange, there’s concern that some people, especially those with respiratory conditions could be impacted. When you’re in the red zone and certainly when we’re in the purple or maroon zones, even if you are a so-called healthy person.”

OK, it says I’m in an area under an air quality alert. I can see and smell the smoke. What should be my primary health concerns?

“The particulate levels are so high that even for a normal person without any underlying medical conditions, it can still be unhealthy and dangerous if there is long-term exposure,” says Dr. Purvi Parikh of the Allergy & Asthma Network. “The longer you’re exposed to it, there’s more chance for it to cause problems. And what is happening with smoke is that these fine particles are able to get deep into your lungs, and these particles contain chemicals, pollution, carbon monoxide that can be damaging to your lungs. So over time, it can cause you to have inflammation. And for some individuals, if you’re exposed constantly, it can even turn into conditions like asthma.”

What’s considered long-term exposure? A few hours?

“Yeah. But like everything in medicine, it depends on the individual and your baseline health status,” Parikh says. “So if you’re a very healthy individual, you know, a couple of hours with a mask should be OK, without having long-term consequences. But if you’re outside exercising or if you’re pregnant, or an elderly person with heart disease or lung disease, or someone who already has an underlying lung condition or immune condition, I would try to limit that exposure as much as possible.”

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Is wildfire smoke the reason my allergies have been worse the last few days?

“Absolutely,” Parikh says. “It can make your allergies worse, because it basically amplifies them, adding more inflammation so your symptoms are much worse too. It makes your eyes burn and your skin itch more. Same thing with your cough — more coughing, wheezing, more asthma attacks. And if you suffer from sinus allergies, this can definitely make it worse because that’s the first port of entry for wildfire smoke — through your nose.”

Officials are encouraging people, especially children or those with underlying conditions like asthma, to limit outdoor activities or stay indoors. What if I have to go outside? Should I wear a mask?

“The best thing to do is check what the air quality is, and if it’s at an unhealthy level and you can stay indoors, that’s the best thing to do,” Parikh says. “But if you absolutely have to go outside, we recommend wearing a mask to limit your exposure. And the medical-grade N95 or KN95 masks are best, similar to COVID times, because they reduce some of those particles getting into your lungs. But even a surgical mask or any type of barrier is helpful.”

Wait, I read somewhere that although N95s can protect against fine particles, they don’t protect against the hazardous gasses in wildfire smoke. Is that true?

“It’s true, it is very likely that we’re even being exposed to some of the gasses,” Parikh says. “With that N95 mask, you can’t filter out everything. I mean, you see how hazy it is in New York City, you can’t see buildings down the street. So that’s why even with the mask, we recommend limiting your time outdoors as much as possible.”

What about pets?

“Absolutely,” Parikh says. “Pets are also at risk because they are afflicted by many of the same lung conditions as we humans are. So of course they’re at risk too.”

“I would be concerned about having a pet outside for long periods of time or having them doing a lot of strenuous exercise or running around,” Scott says. “The thing is, they’re breathing in the same air as we are, and it could lead to airway irritation and may create difficulty breathing for them as well.”

How long will our exposure last?

“One of the challenges with wildfire smoke is that it’s really dependent on weather conditions – the way the wind is carrying the smoke or rain in the forecast,” says William Barrett, national senior director of clean air advocacy with the American Lung Association. “The primary concern of wildfire smoke exposure is that particle pollution can linger for long periods of time and it often takes changes in wind patterns or precipitation to knock it down, moving out of the area. That’s what’s moving the wildfire smoke into the community and what will ultimately move it out.”

When the smoke clears, what should people who are still having symptoms do?

“So let’s say once the air quality returns to safe levels and you notice that you’re still having any type of symptoms a week or two later, you should be checked by a doctor,” Parikh says. “Because what happens is sometimes the exposure can weaken your lungs, weaken your sinuses and then predispose you to developing allergies or leave behind inflammation.”