AQI Scale Flags Rising Lung Risks From 0 to 500 Pollution Levels

Q: When wildfire smoke is high, could the air inside your home potentially be even more toxic than outdoors?

Yes—indoor air can sometimes become as bad as, or even worse than, the air outside during wildfire smoke, especially if smoke is leaking in and the home is adding its own pollution. Wildfire smoke is made up largely of PM2.5, the fine particles most linked to breathing and heart risks. Those particles can enter through cracks, doors, windows and ventilation systems, even when a house is closed up. If the smoke outside is heavy, indoor air can deteriorate quickly, particularly in older or poorly sealed homes. Experts note that if a fire is very close, it may be nearly impossible to keep dense smoke from building up indoors. Indoor conditions can become worse than outdoors when smoke infiltration is combined with pollution generated inside the home. Frying food, burning candles, smoking, using wood stoves or fireplaces, vacuuming, and some scented products can all add fine particles or gases. In that situation, indoor air may be more toxic than the outdoor smoke alone. That said, indoor air is usually meant to be made safer than outdoor air during a smoke event. The key is to keep windows and doors closed, set HVAC systems to recirculate, use MERV-13 or better filters if possible, run a HEPA air cleaner or a DIY box-fan filter, and avoid indoor particle-producing activities. People with asthma, COPD, heart disease, children, older adults and pregnant people should be especially cautious and monitor AQI closely, since it can change hour by hour.

3 articles · Updated · Health News Hub · Jul 16

A 0-to-500 AQI scale signals how likely outdoor air is to trigger breathing problems, with risk rising as pollution from particles, ozone, smoke and exhaust increases.
At 0-50 and 51-100, most people can stay active outdoors, though unusually sensitive people may develop mild cough, throat irritation or get winded during strenuous exercise.
From 101-150, children, older adults, pregnant people and those with asthma, COPD or heart and lung disease face higher risk and should cut back or move activity indoors.
At 151-200, even healthy people may develop coughing, wheezing, chest tightness or shortness of breath; at 201-300 and hazardous levels above that, everyone should minimize time outside.
Dr. Mehak Gandhi said AQI reflects current exposure risk rather than lung damage already done, so people should track hourly changes, reduce exertion and keep rescue inhalers close on poor-air days.