The Same Smoke Doesn't Cost Everyone the Same

The same smoky air doesn't cost everyone the same. Children absorb a bigger dose per pound, people with heart disease face the highest death toll, and pregnant people, older adults, anyone with asthma, COPD, or diabetes, and outdoor workers all pay a steeper price than the general population — some of them well before the AQI turns red.

Why does smoke hit kids harder than adults?

A child breathes faster than an adult, relative to their size — more breaths per minute, more air moved per pound of body weight. That means more PM2.5 reaching the lungs for the same time spent outside. Their lungs are also still building airways and tissue, a process that doesn't finish until the late teens, so damage from repeated smoke exposure lands on a system still under construction. Kids also tend to be outside longer and more active — recess, practice, playgrounds — which adds exposure time on top of the higher dose rate. Infants have it worse still: newborn lungs and a faster resting breathing rate stack the same problem even higher.

Why are heart disease and older age the biggest share of smoke deaths?

PM2.5 doesn't stay in the lungs — particles small enough cross into the bloodstream, where they trigger inflammation, make blood more prone to clotting, and can destabilize the heart's electrical rhythm. In someone with existing heart disease, that's enough to tip a stable condition into a heart attack, stroke, or dangerous arrhythmia within hours of exposure, not years. Older adults carry more of this risk simply because heart and lung disease become more common with age, and the body has less reserve to absorb the added strain. This is why cardiovascular events, not respiratory ones, account for the largest share of deaths tied to wildfire smoke.

PM2.5's most visible effect is a cough. Its most lethal effect is on the heart.

What does wildfire smoke do during pregnancy?

PM2.5 crossing into the bloodstream doesn't stop at the placenta. Studies link fine-particle exposure during pregnancy to slower fetal growth, lower birth weight, and a higher rate of preterm birth — effects that compound the later in pregnancy the exposure happens. The practical response is the same one that protects a newborn afterward: cut outdoor exertion on smoky days and keep indoor air filtered, especially in the third trimester. What actually helps once the baby arrives covers the filtering setup in more detail.

Why do asthma, COPD, and diabetes make smoke more dangerous?

Asthma and COPD start from airways that are already inflamed or narrowed; smoke's fine particles are a direct irritant on top of that, which is why a flare can start within hours of exposure, not days. Diabetes works differently but lands in the same place — it already damages blood vessels and keeps the body in a low-grade inflammatory state, which compounds PM2.5's effect on clotting and heart rhythm rather than the airways. That's why diabetes sits on the same "sensitive group" list as heart disease, even without a lung symptom in sight.

What about people who can't just stay inside?

Outdoor workers — construction, agriculture, delivery, landscaping — don't get to treat a bad AQI reading as a cue to go inside; the job is outside. Low-income households face a version of the same problem indoors: older housing lets more smoke in, and air conditioning or a purifier isn't guaranteed. For both groups, the fix has to travel with them rather than assume a clean room is available: a properly fitted N95 respirator, scheduled breaks in filtered air where the employer provides it, and shifting the heaviest physical work to the cleanest part of the day. Not every mask on shelves actually filters PM2.5 — the fit matters more than the label.

At what AQI should each group act, and how?

These thresholds sit inside the AQI scale's own bands — see the full color-band table and what each one means for the general-population read.

If there's a dog, cat, or bird in the house too, they're breathing the same smoke on the same day — here's what to watch for in pets.

Sources & further reading. EPA — Particulate Matter (PM) Basics; American Heart Association — Particulate Matter Air Pollution and Cardiovascular Disease (Brook et al., Circulation, 2010); Bekkar et al. — Air Pollution and Heat Exposure With Preterm Birth, Low Birth Weight, and Stillbirth (JAMA Network Open, 2020); CDC — Protect Yourself from Wildfire Smoke.

This article is general information, not medical advice. If you're pregnant, caring for an infant, or managing heart disease, lung disease, or diabetes, talk to a doctor about smoke exposure specific to your situation.