5757Moderate“Unhealthy for everyone” starts at 151 — not 201.
Go
Normal outdoor plans. No change needed.
Short & unloaded
A 20-minute dog walk, not a 2.5-hour run. Keep it brief and easy.
Don’t go
Move it indoors. Above 200 that becomes everyone, not just sensitive groups.
Duration and intensity are two separate dials
Verdict by duration and intensity at AQI 57
Under 20 min
20–60 min
Over an hour
Easy
Go
Go
Go
Moderate
Go
Go
Go
Hard
Go
Go
Go
Where people actually draw the line
60 Asthmatic runnerone runner’s own 156-run log
75–100 Daycare / schoolWA 75/80, MN 100 — confirmed; most states not studied
100 Parentcommunity-reported, escalating at 150 and 200
110 Runnercommunity-reported
EPA classifies 101–150 as Unhealthy for Sensitive Groups. That is an attributed
classification, not a verdict on your lungs specifically.
If you’re staying in, filter the room you’re actually in
A portable HEPA unit or a Corsi-Rosenthal box — one builder put theirs at
about $130 for a 12×14 bedroom. We don’t default to a MERV-13 swap in whole-house HVAC:
it can restrict airflow, and the safe version needs a static-pressure check first.
Of the 114 US metros reporting to us right now, Columbia is
number 31 and number 2 of
the 2 we track in South Carolina.
The pollutant driving it today is PM2.5.
Nearby metros we also measure, and what they read at the same hour:
A metro reading differently a short drive away is normal: monitors sit
where they sit, and terrain, traffic and wind do not respect a city boundary.
We have not written a guide for Columbia yet. The 28 metros with
one earned it through months of research into what actually drives their air. This page
gives you the reading, the verdict and our own record; the writing comes when we have
something to say that is specific to this metro rather than generic.
How we measure →
Where this reading comes from
Columbia, about miles from the metro centre, with nearby sensors.
A station miles from where you stand under-reports whichever side of the metro
sits farthest from it.
Our history for Columbia so far
Daily maximum from readings we recorded ourselves — the worst the day
got, which is the number a decision turns on.
We hold 1 day so far, starting 2026-08-16. The chart fills in as we measure; nothing is back-filled.
0 of the 1 day we have recorded so far went above AQI 100.
Questions people ask
What AQI should you stay inside?
It depends who is asking. A runner community-reports 110; a parent around 100;
one asthmatic runner’s own 156-run log put their cutoff at 60. EPA classifies 101–150 as
Unhealthy for Sensitive Groups — an attributed classification, not a verdict on your lungs.
Is it safe to exercise outside today?
Duration and intensity are separate dials. A 20-minute easy walk and a
two-hour hard run at the same number are different decisions.
Why does another app show a different number?
Different averaging windows, different stations, and some apps substitute a
neighbouring city when the local feed drops. Our method →