How can people with asthma or heart disease cope with bad air?

Short answer. People with asthma, COPD or heart disease should act earlier than everyone else: from US AQI 101, the EPA tells them to shorten and lighten outdoor activity, follow their asthma action plan and keep quick-relief medicine handy ¹. Canada's index asks at-risk people to start adjusting at AQHI 4 if they have symptoms ⁴. The CDC advises a 7 to 10-day supply of prescriptions ².

Who is more sensitive to polluted air?

The World Health Organization names children, pregnant women, older people, people living with chronic disease and people in the lowest socioeconomic groups as most at risk ⁸. It estimates that air pollution causes about 6.6 million deaths a year, close to 84% of them from noncommunicable diseases such as heart and lung disease ⁸.

National lists overlap but are not identical:

• United States. The EPA lists people with heart disease, people with lung disease including asthma and COPD, older adults, children and teenagers, pregnant people, minority populations and outdoor workers ¹. Children are included because their lungs are still developing and they breathe more air per pound of body weight than adults ¹. For smoke, the CDC adds diabetes ².
• Canada. Health Canada lists people with lung or heart conditions, people aged 65 and older, infants and young children, pregnant people, and people more exposed because of where they live or work ³.
• Australia. NSW Health lists heart or lung conditions such as asthma, emphysema and angina, pregnancy, age over 65, infants and young children, and diabetes ⁹.

General preparation for older people, babies and people on medication is in the guide to protecting vulnerable people.

Why write an action plan with the doctor before a bad-air day?

Because the right response depends on the condition, and only a clinician can set it. The CDC tells people with asthma to follow their healthcare provider's advice and their asthma action plan if they have one, and tells people with COPD, diabetes or heart disease to talk to their provider about their condition before wildfire season ². NSW Health asks people with asthma to see their doctor about their Asthma Action Plan and to know how to manage a flare-up caused by smoke ⁹.

Questions worth bringing to that appointment, based on what the agencies raise:

• Which symptoms mean "use the reliever", which mean "call the doctor" and which mean "call emergency services"?
• Does the plan change on high-pollution days? The UK Met Office notes that people with asthma may need their reliever inhaler more often at high and very high pollution levels ⁵.
• For diabetes: NSW Health says smoke may make blood glucose harder to manage and suggests asking the doctor for a diabetes management plan ⁹.
• For pregnancy: NSW Health advises talking to a doctor or midwife and reducing exposure where possible ⁹.

Keep medicine within reach. The CDC advises storing a 7 to 10-day supply of prescription medicines in a waterproof, childproof container to take if you evacuate ². NSW Health says to check that reliever medication is up to date and to store it with a spacer in an easy spot ⁹. Asthma + Lung UK says to carry a reliever at all times and use it as soon as symptoms appear ⁶. Building a longer reserve is covered in the guide to emergency medication.

At what pollution level should sensitive people act?

Earlier than the general public, on every national scale. The full category tables are in the guide to wildfire smoke; this table shows only the level where advice for sensitive people starts and where it becomes strict.

The scales are not interchangeable: read each number on its own national scale.

How should sensitive people exercise on polluted days?

Lighter, shorter, and indoors when it gets bad. At AQI 101–150 the EPA says it is OK for sensitive groups to be active outdoors with more breaks, and to watch for coughing or shortness of breath ¹. From 151 it says to avoid long or intense outdoor activities and consider moving indoors ¹. It also suggests exercising away from busy roads ¹. When smoke lasts several days, Health Canada suggests exercising indoors in a place with cleaner air ³.

One caution: without air conditioning, staying inside with windows closed may be dangerous in extreme heat, the EPA warns ¹; NSW Health suggests air-conditioned libraries and shopping centres ¹⁰.

Should sensitive people stay in a clean-air room or wear a mask?

Filtered indoor air comes first. Particle levels can be high indoors when they are high outside, so the EPA advises cutting indoor sources such as candles and wood stoves and using HEPA or portable air cleaners ¹. Setting up one filtered room is explained in the guide to the clean-air room.

A respirator is a second line, and for this group it calls for medical advice first. NSW Health tells people who are more sensitive to smoke to follow their doctor's advice on how to stay safe, and to consider P2/N95 masks only if exposure cannot be avoided ¹⁰. Which masks filter what, and who should ask a doctor before wearing one, are covered in the guide to masks for smoke.

Which signs mean urgent help is needed?

These are general warnings from the agencies, not a substitute for a personal plan.

• Call emergency services (911, 999, 000) for severe trouble breathing, chest pain, or a suspected heart attack or stroke (CDC) ²; for difficulty breathing, chest pain or a medical emergency (NSW Health) ¹⁰.
• During an asthma attack, the NHS says to call 999 if the person feels worse at any time, does not improve after the maximum dose of their reliever, or has no inhaler ⁷.
• Contact a health professional for heart palpitations, unusual fatigue or shortness of breath in people with heart disease (EPA, CDC) ¹²; for dizziness, wheezing, chest pains, severe cough, asthma attacks, shortness of breath or palpitations (Health Canada, which says to talk to a provider or seek urgent medical attention) ³.
• Watch for slower signs: coughing more, wheezing, more breathlessness outdoors, or needing the reliever more often (Asthma + Lung UK) ⁶.

What official agencies recommend

• United States (EPA, AirNow, CDC). Sensitive groups act from AQI 101 ¹. Keep a 7 to 10-day prescription supply and tell shelter staff about asthma, COPD, diabetes or heart disease ².
• Canada (Health Canada, ECCC). At-risk people reduce or reschedule strenuous outdoor activity at AQHI 7 to 10 and avoid it at 10+ ⁴. Exercise indoors in cleaner air during long smoke events ³.
• United Kingdom (Met Office, NHS, Asthma + Lung UK). Lung and heart patients cut strenuous activity from DAQI 7 and avoid it at 10 ⁵. Carry the reliever ⁶; call 999 when an attack does not respond to it ⁷.
• Australia (NSW Health). Review the action plan with a doctor, keep the reliever with a spacer within reach, and ask for a diabetes plan ⁹.
• World Health Organization. Children, pregnant women, older people and people with chronic disease are most at risk ⁸.

Where they differ:

• Diabetes. The CDC and NSW Health list it as a risk factor ²⁹; the EPA particle guide and Health Canada do not name it ¹³.
• Who else counts. The EPA includes minority populations and outdoor workers ¹; Health Canada includes people exposed by location or occupation ³.
• Starting point. The EPA's advice begins at AQI 51 for unusually sensitive people ¹; Canada and the UK start at index 4, and only for people with symptoms ⁴⁵.

Frequently asked questions

Should someone with asthma stop exercising when the air is bad?

Not always. At US AQI 101–150 the EPA says sensitive groups can stay active outdoors with lighter sessions and more breaks; from 201 they should avoid all outdoor physical activity ¹. Their own action plan comes first.

Is polluted air dangerous during pregnancy?

NSW Health says brief smoke exposure is unlikely to affect the mother or baby, but continuous exposure for more than one week may increase risks such as preterm birth and lower birth weight ⁹. The WHO counts pregnant women among the groups most at risk ⁸.

Should someone with heart disease wear an N95?

Only after medical advice. NSW Health tells sensitive people to follow their doctor's advice and to consider P2/N95 masks only when exposure cannot be avoided ¹⁰. Staying in filtered indoor air comes first ¹.

Your household's air risks, in your plan

Air quality forecasts and alerts are explained country by country.

The Phaenyx plan's "Water and air" section lists the water and air risks for your postal code, so you can prepare a sensitive person's plan before a bad-air day. The Phaenyx Safe app keeps the reflex sheets offline. Build your Phaenyx plan.

Sources

1. U.S. Environmental Protection Agency (EPA) / AirNow — Air Quality Guide for Particle Pollution (EPA-452/F-23-002) — https://www.airnow.gov/sites/default/files/2023-03/air-quality-guide-for-particle-pollution_0.pdf (accessed 2026-10-27)
2. Centers for Disease Control and Prevention (CDC) — Wildfire Smoke and People with Chronic Conditions — https://www.cdc.gov/wildfires/risk-factors/wildfire-smoke-and-people-with-chronic-conditions.html (accessed 2026-10-27)
3. Health Canada — Wildfire smoke and your health — https://www.canada.ca/en/health-canada/services/publications/healthy-living/wildfire-smoke-health.html (accessed 2026-10-27)
4. Environment and Climate Change Canada — About the Air Quality Health Index — https://www.canada.ca/en/environment-climate-change/services/air-quality-health-index/about.html (accessed 2026-10-27)
5. Met Office (UK) — Air pollution — https://weather.metoffice.gov.uk/guides/air-quality (accessed 2026-10-27)
6. Asthma + Lung UK — Air pollution effects on your lungs, including lung cancer — https://www.asthmaandlung.org.uk/living-with/air-pollution/your-lungs (accessed 2026-10-27)
7. NHS (UK) — Asthma — https://www.nhs.uk/conditions/asthma/ (accessed 2026-10-27)
8. World Health Organization (WHO) — Health effects of air pollution: evidence and implications: technical brief — https://www.who.int/publications/i/item/B09563 (accessed 2026-10-27)
9. NSW Health (Australia) — Know if you are at higher risk from bushfire smoke — https://www.health.nsw.gov.au/environment/bushfire/Pages/know-high-risk.aspx (accessed 2026-10-27)
10. NSW Health (Australia) — Protect yourself from bushfire smoke — https://www.health.nsw.gov.au/environment/bushfire/Pages/bushfire-protection.aspx (accessed 2026-10-27)