The Air / Southern California
Air quality in Pasadena right now
PASADENA — The air over Pasadena reads 68 on the federal index this afternoon — moderate.
The pollutants, against the WHO guideline
| Pollutant | Now | WHO 24h | × guideline |
|---|---|---|---|
| PM2.5 µg/m³ | 9.2 | 15 | 0.6× |
| PM10 µg/m³ | 10.2 | 45 | 0.2× |
| Ozone µg/m³ | 111 | 100 | 1.1× |
| NO₂ µg/m³ | 12.9 | 25 | 0.5× |
| SO₂ µg/m³ | 4.9 | 40 | 0.1× |
| CO mg/m³ | 0.2 | 4 | 0.0× |
Source: Open-Meteo (Copernicus CAMS) · WHO 2021 global air quality guidelines · No figure on this page is written by hand.
What this air means
For most people this air changes nothing. The most sensitive — people with asthma, COPD, or heart disease — may notice it on long, hard exertion outdoors; everyone else can carry on.
The mechanism, briefly
Particles under 2.5 microns — a fortieth the width of a hair — ride air all the way to the alveoli, the one-cell-thick membrane where the lung hands oxygen to the blood. The membrane cannot tell oxygen’s friends from its enemies: within an hour of significant exposure, ultrafine particulate is circulating. That is why the numbers on this page are worth checking — dose is the only variable you control.
From the Air desk
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Air pollution is taking lung tissue, not just irritating it — and the pollutant still doing it is ozone
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We invented a government cover-up that does not exist. Here is how the AQI in your phone is actually calculated.
Sol Index
The lid over a heat dome is sinking air, not the stratosphere — and it is what kills the Delta breeze
Cael Frost
Nearby
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