Who's Most at Risk From Wildfire Smoke — and the Warning Signs That Mean It's Time to Get Help

Wildfire smoke has settled over much of Ontario, and emergency departments are seeing more people arrive with breathing problems. When the air turns hazy and you can smell smoke, it's normal to wonder how worried you should be — and when a cough or scratchy throat is something more serious.

This guide explains who is more likely to be affected by wildfire smoke, why, and — most importantly — the warning signs that mean you should stop waiting and get help right away.

The single most useful thing to know: most people feel some irritation during a smoke event, but a smaller number develop serious problems that need urgent care. Knowing the difference can save a life.

What's actually in the smoke

Wildfire smoke is a mix of gases and tiny particles. The biggest health concern is fine particulate matter, often called PM2.5. These particles are far too small to see, and they can travel deep into your lungs. According to Health Canada, there is no known safe level of exposure to some of the pollutants in smoke — meaning it can affect your health even at lower levels, and during heavy smoke, everyone is at some risk regardless of age or health. [1]

That's why paying attention to how you feel matters more than how bad the air looks outside.

Who is at higher risk — and why

Some people feel the effects of smoke sooner, and more strongly, than others. Being in one of these groups doesn't mean something bad will happen — it means it's worth watching your symptoms more closely and acting sooner.

People with asthma, COPD, or other lung conditions. Smoke particles settle deep in the lungs and can irritate already-sensitive airways. Health Canada notes that people with conditions such as asthma, chronic bronchitis, and emphysema are more sensitive to the effects of smoke. [1] For someone with asthma or COPD, smoke can trigger a flare-up that's harder to control than usual.

People with heart disease. Public Health Ontario notes that people with underlying heart conditions — such as heart failure or coronary artery disease — may find their condition worsens with smoke exposure, and some experience symptoms like a racing heart, fatigue, or dizziness. [2]

Older adults. Health Canada lists the elderly among those more sensitive to smoke, in part because heart and lung conditions become more common with age. [1]

Infants and young children. Children breathe faster than adults and take in more air for their size, and their lungs are still developing. Many children feel the effects of smoke at lower levels than healthy adults do. [2]

Pregnant people. Pregnancy brings physical changes that can make smoke harder to tolerate. The U.S. Centers for Disease Control and Prevention (CDC) lists pregnant people among those at higher risk from wildfire smoke and advises limiting time outdoors during smoky conditions. [3]

People who work or exercise outdoors. Spending long hours outside — or breathing hard during exercise or physical work — means taking in more smoke. The CDC identifies outdoor workers and people doing vigorous outdoor activity as higher-risk groups. [4]

What's expected — and what's a warning sign

Most people exposed to wildfire smoke will notice some mild, short-lived irritation. Health Canada describes common symptoms such as a sore throat, cough, and stinging or watering eyes. [1] These are your body reacting to an irritant. They're uncomfortable, but on their own they're usually not an emergency — and they tend to ease once you get to cleaner air.

Warning signs are different. They point to your lungs, heart, or oxygen levels being under real strain. These are not symptoms to "wait out."

Red flags — call 911 or go to the emergency department now

Call 911 or go to the nearest emergency department right away if you or someone with you has any of the following during a smoke event:

• Severe shortness of breath or serious trouble breathing — struggling to catch your breath, or unable to speak in full sentences
• Chest pain or chest tightness
• Wheezing that won't settle down
• Confusion, severe dizziness, or fainting
• A severe asthma or COPD flare-up that is not improving after using your usual reliever (rescue) inhaler
• Bluish lips or fingertips

The CDC advises calling 911 or going straight to an emergency department for medical emergencies such as severe trouble breathing, chest pain, or signs of a heart attack or stroke. [4] Asthma Canada is equally direct: an asthma attack can be a life-threatening emergency, and you should never hesitate to call 911 if your symptoms persist or if there's no improvement after taking your reliever medication. [5]

If you're not sure whether something counts as an emergency, treat it as one. It is always better to be checked and sent home than to wait too long.

When to contact a healthcare professional (not an emergency)

Between mild irritation and a true emergency, there's a middle zone — and this is where a lot of people get caught. You don't need an ambulance, but you shouldn't just push through, either.

Contact your family doctor, a walk-in clinic, or a pharmacist promptly if:

• You have new symptoms that aren't easing, or symptoms that keep getting worse
• You have a chronic condition — like asthma, COPD, or heart disease — that is becoming harder to manage than usual during the smoke
• You're using your reliever inhaler more often than normal, but you're not in a full-blown crisis
• You're running low on a regular medication and need a refill to get through the smoke event
• You're unsure whether your symptoms are normal and want advice from a professional

A pharmacist is often the easiest professional to reach quickly, and they can help you review your medications and inhaler technique. Your family doctor or a walk-in clinic can adjust a treatment plan before a small problem becomes a big one. The CDC advises people with conditions like asthma or heart disease to monitor their symptoms and seek medical care when needed, and to keep prescriptions up to date with enough supply on hand. [4]

A note on where to go: For breathing emergencies, the emergency department is the right place — not a specialist's office. For ongoing concerns, start with your family doctor, a walk-in clinic, or a pharmacist. There's no need to track down a lung specialist on your own during a smoke event; your regular care team can guide you and refer you if needed.

Have a plan — especially if you have a chronic condition

The best time to prepare is before your symptoms flare. A little planning takes the panic out of a bad-air day.

If you have asthma, COPD, or a heart condition:

• Keep your reliever (rescue) inhaler and daily medications with you and topped up. Asthma Canada recommends carrying your reliever inhaler with you at all times during smoke season. [5]
• Know your action plan. If you have an asthma action plan, review it so you know exactly what steps to take as symptoms change, and when those steps mean it's time to call for help. [5]
• Reduce your exposure indoors. Public Health Ontario suggests keeping windows closed, running your HVAC fan on recirculate, and using a portable air cleaner where you can to lower the amount of smoke getting inside. [2]
• Take it easy. Limit hard physical activity and time outdoors while the air quality is poor, and check your local Air Quality Health Index so you know when conditions are worst. [1]

For everyone else, the same basics help: stay indoors when the air is thick, keep smoke out of your home where you can, and check on the people around you who are more vulnerable — older neighbours, young children, and anyone with a lung or heart condition.

The bottom line

Wildfire smoke affects almost everyone a little, and some people a lot. Mild irritation — a cough, a sore throat, itchy eyes — is common and usually settles in cleaner air. But severe breathing trouble, chest pain, a flare that won't respond to your reliever, or confusion and fainting are warning signs that need emergency care: call 911 or go to the emergency department. For symptoms that are new, worsening, or making a chronic condition harder to manage, don't wait it out — contact your family doctor, a walk-in clinic, or a pharmacist promptly.

Trust what your body is telling you, act early, and lean on your care team. During a smoke event, getting help sooner is always the safer choice.

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If any of the urgent warning signs described above apply to you, don't wait for an appointment — seek medical care now.