Air Quality in Honolulu, Hawaii — Live

Live readings from PurpleAir sensors across Honolulu — with free alerts when vog drifts in from Kilauea.

Live Honolulu AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Honolulu and Pearl City, Kailua, Kaneohe, Waipahu.

Honolulu has some of the cleanest air of any major U.S. city most of the year. The trade winds that blow steadily off the open Pacific keep pollution from building up, and the city's annual PM2.5 average — roughly 3.5 to 4 micrograms per cubic meter — sits well inside the World Health Organization's guideline. The real exception is vog: volcanic smog from Kilauea, more than 200 miles away on Hawaii Island, which can drift over Oahu when those trade winds weaken or reverse, mostly in winter.

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.

Honolulu's air is about as clean as it gets

Government monitoring and independent tracking from IQAir both put Honolulu's annual average PM2.5 at roughly 3.5 to 4 micrograms per cubic meter in recent years — under the World Health Organization's annual guideline of 5, and cleaner than almost any major mainland city. Most of that comes down to geography: Oahu sits in the open Pacific with nothing upwind for thousands of miles, and the northeast trade winds that blow on most days constantly flush the island's air out to sea.

That steady wind is also why Honolulu rarely deals with the kind of local pollution that piles up in valley or basin cities — there's no ridgeline here to hold smoke or exhaust in place overnight. The tradeoff is that when the trade winds do weaken or reverse, a shift locals call Kona weather, whatever is in the air has nowhere to go and can hang around longer than usual.

The real story here is vog, drifting over from Kilauea

Oahu has no active volcanoes of its own, but it sits downwind of one of the most active volcanoes on Earth. Kilauea, on Hawaii Island roughly 200 miles southeast, has erupted repeatedly since December 2020, with further episodes in 2021, 2022, 2023, and 2024. Each eruption releases sulfur dioxide that reacts with sunlight, moisture, and oxygen to form the fine sulfate particles known as vog. The City and County of Honolulu's 2025 hazard mitigation plan specifically calls out the September 2023 eruption, which released an estimated 209,000 tons of sulfur dioxide a day, as a vog-producing event felt beyond Hawaii Island.

Under normal conditions, the northeast trade winds push that plume toward the Kona side of Hawaii Island and out over open ocean, sparing Oahu almost entirely. It's when those trade winds go quiet — most often in winter — that vog can spread across the whole state, including Honolulu. By the time it reaches Oahu it has mostly converted to fine PM2.5 rather than raw sulfur dioxide gas, so the city's own hazard plan rates the health impact here as minor for most residents, occasionally reaching levels that matter for people with asthma, heart conditions, or other sensitivities.

How the state tracks it, and what the color codes mean

The Hawaii Department of Health runs stationary air monitors on Oahu at Honolulu, Kapolei, and Sand Island, tracking PM2.5, PM10, and sulfur dioxide, while the USGS Hawaiian Volcano Observatory tracks Kilauea's gas emissions to help forecast vog days before it arrives. The state uses a color-coded sulfur dioxide advisory scale — green, yellow, orange, red, purple, and maroon — running from 'good' to 'hazardous,' with sensitive groups advised to take precautions well before conditions affect the general population.

Those three official stations cover a lot of ground for one island, though, which is where a denser network helps. Canairy reads PurpleAir sensors scattered across Honolulu's neighborhoods, from downtown to the east side, so you can see how the air near your own house compares to the citywide picture instead of relying on whichever official monitor happens to be closest.

Honolulu air quality FAQ

What is the air quality in Honolulu right now?

This page shows the current AQI for Honolulu, calculated from PurpleAir sensors across the city and updated continuously. The map below shows every live sensor, so you can check the reading closest to your own neighborhood.

Why does Honolulu sometimes get hazy — is that vog?

Usually, yes. Vog is volcanic smog that drifts over from Kilauea on Hawaii Island, more than 200 miles away. Trade winds normally carry it out to sea before it reaches Oahu, but when those winds weaken or reverse — most often in winter — vog can settle over Honolulu as a fine haze. On Oahu it shows up mostly as elevated PM2.5 rather than the stronger sulfur dioxide levels found closer to the volcano.

Is Honolulu's air quality usually good?

Yes. Honolulu's annual average PM2.5 typically runs around 3.5 to 4 micrograms per cubic meter, well inside the World Health Organization's guideline, thanks to steady trade winds off the open Pacific. The main exception is vog from Kilauea, which can raise particle levels for a few days at a time, mostly in winter when the trade winds falter.

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.

Where does Canairy's Honolulu data come from?

Readings come from PurpleAir's network of laser particle sensors across Honolulu and surrounding towns, cross-referenced with government monitors and the Google Air Quality API. You can see every sensor behind your numbers on the live map - there's no black box.

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.