Air Quality in Fremont, California — Live

Live readings from PurpleAir sensors across Fremont — with free alerts the moment the air turns.

Live Fremont AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Fremont and Union City, Newark, Hayward, Milpitas.

Fremont sits at the south end of the East Bay with the bay on one side and the Diablo Range on the other, and for most of the year that geography gives it good air. Across its whole monitoring network in 2023, the Bay Area Air Quality Management District recorded four days over the national 8-hour ozone standard and three days over the national 24-hour PM2.5 standard. What makes Fremont worth watching is not the annual average — it is the specific things sitting inside the city and just behind it: a car plant with a long enforcement history, I-880 and I-680 both running through town, and hills that have burned twice in recent memory.

Canairy watches the sensors around your home, your kids' school, and everywhere else you care about, and tells you in plain English when the air changes enough to matter.

The factory on the east side of town

In June 2024 the Air District's Hearing Board ordered Tesla to fix ongoing air quality violations at its Fremont factory. The Air District said Tesla had racked up more than 112 notices of violation since 2019, nearly all of them traced to the plant's two paint shops, where the thermal oxidizer meant to destroy solvent vapours broke down repeatedly and was sometimes shut off while other equipment was being repaired. The pollutants at issue were precursor organic compounds — which react with nitrogen oxides in sunlight to form ozone — and toxic air contaminants.

The order gave Tesla roughly fifteen months to hire an outside engineering firm and produce a plan, then another six months to carry it out once the Hearing Board approved it. Separately, in February 2024 Tesla settled a hazardous waste case brought by California district attorneys, covering Fremont among other sites, for $1.5 million. One honest caveat: a neighbourhood sensor measures fine particles, not solvent vapours, so a paint shop release will not necessarily show up as a spike on the map below.

Fires start in the hills behind Fremont

The hills east of the city are the northern end of the Diablo Range, and they burn. The SCU Lightning Complex ignited in dry lightning on 16 August 2020 and burned 396,624 acres across Santa Clara, Alameda, Contra Costa, San Joaquin, Merced and Stanislaus counties before containment on 1 October — the fifth-largest wildfire in California's modern record, with 222 structures destroyed and no lives lost. Its Canyon Zone burned in Alameda and Santa Clara counties, in the range directly behind Fremont.

More recently, the Little Fire started just before 3pm on 21 July 2026 near Little Valley Road south of Pleasanton, reached 1,007 acres, and forced evacuations north of State Route 84 in Sunol — up Niles Canyon from Fremont's Niles district. The Air District warned that smoke would affect East Bay air quality, but said levels were not expected to exceed the national 24-hour standard, and no Spare the Air alert was issued. That is the more typical pattern here: a fire close enough to see and smell without a regionwide smoke event.

Most of the year, the bay does the work

The Air District describes Alameda County as split. In the western half, near the bay, ozone rarely exceeds health standards because the water moderates temperatures. In the eastern half, around the Livermore Valley, summer afternoons frequently approach triple digits and ozone runs the highest in the Bay Area. Fremont is firmly on the bayside half of that split, with Coyote Hills and the Don Edwards San Francisco Bay National Wildlife Refuge between the city and open water.

That is also why the sky can look far worse than the air actually is. On 9 September 2020, smoke from the North Complex and more than twenty other fires blocked out the sun across Northern California and held Bay Area skies orange all day — bridge and street lights stayed on, drivers were told to use headlights — while ground-level air quality read 90, in the moderate band. Your eyes and the sensor will not always agree, in either direction.

Fremont air quality FAQ

Why is there smoke in Fremont today?

Check the hills first. Fires in the Diablo Range east and south of the city, or up Niles Canyon toward Sunol, put visible smoke over Fremont without necessarily pushing the AQI far. The Little Fire near Sunol and Pleasanton in July 2026 burned over a thousand acres and the Air District expected East Bay smoke, but pollution was not forecast to exceed the national 24-hour standard. If there is no local fire in the news, it is more likely smoke drifting in from a larger fire elsewhere in Northern California, or on a cold winter evening, wood smoke from fireplaces settling in the flatlands.

What is the air quality in Fremont right now?

This page shows the current AQI for Fremont, calculated from PurpleAir sensors across the city and updated continuously. Fremont covers a lot of ground — the Niles and Mission San Jose sides sit against the hills, while Ardenwood and Centerville are out toward the bay — and on a still day those can read differently. The map below shows every live sensor so you can find the one nearest you.

Does the Tesla factory affect Fremont's air?

Regulators say it has. The Air District issued Tesla more than 112 notices of violation between 2019 and 2024 over uncontrolled releases from the factory's paint shops, and in June 2024 the Hearing Board ordered the company to fix the underlying equipment problems on a set timeline. The pollutants involved were ozone-forming organic compounds and toxic air contaminants — which are not the same thing as fine particles, and are not what a PurpleAir sensor reads. The sensors on this page are a good guide to smoke and general particulate conditions, not to solvent vapours.

When is Fremont's air usually at its worst?

Two windows. Late summer and early autumn, when Northern California fires are burning and smoke can arrive from hundreds of miles away — August and September 2020 were the extreme version of that. And cold, still winter nights, when wood smoke from fireplaces and stoves gets trapped near the ground; that is the season the Air District issues winter Spare the Air alerts and bans wood burning across the nine counties. The rest of the year, onshore air off the bay usually keeps things in the Good range.

What AQI level is unhealthy?

Under the US EPA scale, AQI 0–50 is Good and 51–100 is Moderate. From 101 the air is Unhealthy for Sensitive Groups — kids, older adults, and people with asthma or heart conditions — and above 150 it's Unhealthy for everyone. Canairy translates these numbers into a plain-English verdict, like whether to close the windows or move a workout indoors.

Is Canairy free?

Yes. The Canairy app is free to download and includes live air quality for all your saved places, plain-English verdicts, and free push alerts when the air crosses your threshold. A paid plan adds extras like SMS text alerts.

Get Canairy free on Google Play.