AQI Detail Page
AQI 400: cigarette equivalent, interpretation, and what to do next
At AQI 400, a full day of exposure is roughly equivalent to smoking 15.93 cigarettes.
AQI category
Hazardous
PM2.5 estimate
350.4
µg/m³
Daily equivalent
15.93
cigarettes / 24h
If repeated daily
477.9
cigarettes / 30 days
What AQI 400 means
Avoid outdoor exposure unless it is essential, and use layered indoor protection.
People with breathing or heart problems may need professional medical advice if symptoms worsen.
Exposure framing
1 hour: about 0.66 cigarettes.
2 hours: about 1.33 cigarettes.
24 hours: about 15.93 cigarettes.
7 repeated days: about 111.5 cigarettes.
Scenario guidance at AQI 400
These are the kinds of day-to-day decisions users commonly make from this reading.
Commute or errands
Avoid2 hours equals 1.33 cigarettes at AQI 400.
Delay nonessential errands and consolidate unavoidable travel.
Outdoor exercise
Avoid1 hour equals 0.66 cigarettes at AQI 400.
Skip outdoor exercise and wait for cleaner air.
Kids, school, or playground time
Avoid3 hours equals 1.99 cigarettes at AQI 400.
Keep children inside and use the cleanest indoor space you can maintain.
Sleeping with windows open
Avoid8 hours equals 5.31 cigarettes at AQI 400.
Seal the room as much as possible and run filtration continuously.
Why the estimate is credible
The site first converts AQI into an estimated PM2.5 concentration and then applies Berkeley Earth’s cigarette-equivalence framing.
The estimate is most useful for comparing air-quality dose across times, situations, and repeated days. It should not be treated as a literal smoking-equivalence medical claim.
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