Irvine, CA Air Quality Index (AQI) Today

That reading is today’s call on Irvine air quality — color first, number right behind it. What it decides is smaller than the headline. The loop around the park. Whether soccer practice moves indoors. Whether tonight’s windows stay open. This page also tracks the air quality Irvine has breathed since we began measuring here, not just the figure refreshing above. Skip refreshing it yourself. Pick your number and be told when the basin crosses it instead.

How does today compare with Irvine’s record so far?

We hold no series for Irvine yet — we record history only from a regulatory monitor. Why.

A single reading hides the shape behind it. BreatheCheck rebuilds the air quality Irvine has seen since we began measuring here, off the same hourly AQI feed as the number above.

The page also carries a running count of days above AQI 100 since we began counting. IQAir, AccuWeather and the state’s own monitor grid stop at today’s figure; none show the metro’s shape over time. Irvine runs ozone-dominant, the same bracket as Los Angeles, Denver, Houston and Phoenix. Afternoon spikes come on hot, still days, not one long winter smear. A rough Tuesday that clears by Thursday still shows up here.

Why is it hazy in Irvine today?

Irvine looks coastal and behaves inland. The San Joaquin Hills sit to the southwest, the Santa Ana Mountains’ foothills to the northeast, and the marine layer that keeps the immediate coastline clear pushes inland and stalls against that high ground — trapping what the basin’s own traffic produces instead of clearing it.

Same basin, same mechanism as Los Angeles — opposite outcome, for a city that looks, on the map, like it should catch a coastal break. Los Angeles sits in the wider version of this basin. Long Beach adds the port complex’s own traffic to it. Both feed air that eventually reaches Irvine.

The sky can also look worse than the number. Smoothing across recent hours holds back a bad afternoon for a few hours. Smoke from a basin fire can sit aloft, above the monitor. Or the nearest station just sits far enough away that it’s standing in for ground it isn’t actually over. A marine layer, an inland push, an averaged number works through each cause.

What is causing the bad air in Irvine?

Ground-level ozone, which is why a clear afternoon can still post a mediocre number. Sunlight cooks vehicle exhaust into ozone through the day, peaking on hot, still afternoons — often worse a few miles inland than right at the beach.

Irvine sits between two of the region’s busiest corridors, I-5 and the 405, and their exhaust has all day to react before the hills stop it from draining out. The EPA AQI breakpoints track six pollutants in total — PM2.5, PM10, ozone, NO2, SO2 and CO — and ozone is the one that dominates an Irvine afternoon. Wildfire smoke reaches Irvine too, riding the same basin currents that carry it into Los Angeles and Long Beach. We don’t have an Irvine-specific fire event on file, so we’re not inventing one. What’s actually in that smoke covers the mechanics, including here.

What makes the call different in Irvine?

The call splits three ways here, not two. Go on a clean reading. Short and unloaded: the short dog loop instead of the long one. Don’t go past the middle band — EPA’s everyone warning opens at 151, Unhealthy.

Irvine sits close enough to the coast that a marine layer should clear the air the way it does right at the beach. Instead, the San Joaquin Hills and the Santa Ana foothills box that layer in, trapping the same basin traffic Los Angeles deals with, just from the inland side. 201 to 300, Very Unhealthy, is the same warning restated more seriously, not a different group. Past roughly 200, the coastal address doesn’t buy an exception.

What AQI should you stay inside?

Nothing California-specific turned up for a school or daycare AQI rule in the material reviewed here. The Washington and Minnesota figures sometimes cited are single centres described by a teacher and parents, not state policy. Whether a daycare AQI rule is documented anywhere covers what’s confirmed.

Marine-layer haze and wildfire smoke shift personal thresholds by different amounts, and neither matches the EPA’s single sensitive-groups line to start with. An asthmatic runner logged 156 runs against AQI and set a ceiling of 60 — “my lungs struggle regardless of how well I’ve trained,” despite EPA calling nothing under 100 unhealthy. That log: 87% of runs under 50 went fine, 42% between 50 and 70, just 12% past 70. A runner on r/Marathon_Training runs nearly double that: “I’ll run in up to 110 because…error bars.” Parents this project has seen online land nearer 100.

Wildfire smoke, arriving on the same Santa Ana winds Los Angeles gets, pulls that whole table down about one EPA band. EPA’s name for that window is the Unhealthy for Sensitive Groups band, 101–150 — the agency’s, not this page’s judgment. Indoors, default to a portable HEPA purifier or a Corsi-Rosenthal box; one builder priced a 12x14 bedroom’s worth at $130. A whole-house MERV-13 swap needs a static-pressure check from a licensed tech first — it isn’t automatic in an inland system built for a marine-layer climate. What to buy indoors, and in which order covers it.

Why our number may not match what you are seeing and smelling

This runs both directions.

Direction one: the sky looks clear, the number is bad. Ground-level ozone, the dominant pollutant here, is invisible and odorless. A bright, still afternoon with no visible haze can still carry an AQI in the 100s. There’s no smelling your way to a safe read on it — only checking the number.

Direction two: the sky looks wrong, and the official line stays calm. It’s the same mechanics above, running in reverse — smoke sitting aloft, a distant station, smoothing across recent hours holding back a rough hour.

No EPA regulatory monitor near Irvine reports to us, so today’s number is modelled rather than read off an instrument.

A station miles off under-reports whichever direction of the metro sits farthest from it. How much a station a few miles off changes the reading has the detail.

Search interest in air quality Irvine doesn’t come with its own named phenomenon, the way “brown cloud” names Denver’s or “smoke aloft” names Seattle’s. No local thread on file names one for Irvine specifically. That gap is stated here plainly, rather than filled with borrowed color. How Irvine ranks against every other tracked city today updates with the live number.