The Air / Bay Area

Air quality in Fremont right now

41GoodUS AQI · updated 6:11 PM PT

FREMONT — The air over Fremont reads 41 on the federal index this evening — good.

The pollutants, against the WHO guideline

Pollutant	Now	WHO 24h	× guideline
PM2.5 µg/m³	3.8	15	0.3×
PM10 µg/m³	5.2	45	0.1×
Ozone µg/m³	82	100	0.8×
NO₂ µg/m³	3.3	25	0.1×
SO₂ µg/m³	0.9	40	0.0×
CO mg/m³	0.1	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

Air this clean is what lungs are built for. No adjustment needed — if you have outdoor plans, this is the hour for them.

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

Our carbon is turning the ocean acidic — and dissolving the shells of the snails the food web runs onRiver Mast PM2.5 doesn't just irritate your lungs — new pathology shows it permanently rebuilds the tissueIris Vale Governments smooth the spikes out of air-quality data before you see it — here's the math that hides the worst hoursSol Index A lid of warm air is trapping the heat domes over the Northern Hemisphere — and it won't moveCael Frost

Nearby

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