Air Quality in Pearl City, Hawaii — Live
Live readings from PurpleAir sensors across Pearl City — with free alerts the moment vog or smoke moves in.
AQI 1 from 4 PurpleAir sensors · Holding steady · data from PurpleAir
As of , the air quality in Pearl City, Hawaii is AQI 1 — Good and holding steady — with PM2.5 at 0.1 µg/m³, the median of 4 live PurpleAir sensors reading 0 to 1. Canairy's verdict: Breathe easy.
For scale, that PM2.5 reading is below the World Health Organization's 24-hour guideline of 15 µg/m³. The WHO figure is a daily average and this is a live reading, so read it as a sense of magnitude rather than a formal exceedance — a brief spike and a bad day are not the same thing. More on the WHO guidelines
Pollen today in Pearl City: grass pollen is the strongest of the three at a none level, from Google's pollen forecast. Canairy shows the tree, grass and weed forecast beside the air reading on every plan, including the free one.
Free to download · Live data from PurpleAir & public monitors
Live PurpleAir sensor map for Pearl City and Aiea, Waipahu, Waimalu, Mililani. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Pearl City
The sensors Canairy reads in Pearl City agree right now — all 4 sit in the Good band, a 1-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 1.2 mi SE | 0 | Good |
| 2.1 mi WNW | 1 | Good |
| 2.5 mi WSW | 1 | Good |
| 3.7 mi WNW | 1 | Good |
Most of the year, Pearl City's air is about as good as anywhere in the country. The town sits on the leeward, dry side of Oahu in the rain shadow of the Ko'olau Range, where steady northeast trade winds usually keep the sky clear and keep pollution from settling. The exception comes on a few dozen days a year, when the trades weaken or reverse ahead of a winter storm and vog — volcanic haze from the Big Island's Kilauea volcano, more than 200 miles away — drifts up and settles over leeward Oahu, along with the occasional smoke from a dry-season brush fire in the grasslands just west of town.
What Canairy does for Pearl City
A clear verdict
Not just a number — a plain-English call for Pearl City: open the windows, or keep them shut.
Smoke alerts
A push or text the moment the air crosses your threshold — and again when it clears.
A heads-up before it's bad
Trend alerts catch the air turning, so you can close up the house before the smoke settles in.
Every place you care about
Home, work, the kids' school — across Pearl City or across the country, on one screen.
Pearl City sits in Oahu's dry, trade-wind shadow
Pearl City sits along the north shore of Pearl Harbor in the Ewa District, on the leeward side of the Ko'olau Range that runs down Oahu's spine. Moist trade-wind air rises and drops its rain on the windward side, over Kaneohe and Kailua, before it ever reaches town — which is one reason Pearl City stays noticeably drier and sunnier than the mountains a few miles east even on an average trade-wind day. Under that normal northeast flow, the same steady breeze that keeps the leeward side dry also keeps its air moving, so pollution rarely has a chance to build up.
That pattern depends on the trades actually blowing, and they blow less than they used to. State climatologist Pao-Shin Chu has tracked Hawaii's trade winds falling from about 291 days a year in 1972 to roughly 210 days more recently, a decline researchers say could add dozens more stagnant-air days across Oahu each year. When the trades stall or reverse into a southerly Kona wind, the sea breeze that normally scours the Ewa Plain clean stops doing its job.
Vog from a volcano 200 miles away reaches Pearl City
Kilauea, on the Big Island, is normally shielded from Oahu by the trade winds, which carry its sulfur dioxide plume southwest toward the Kona coast instead. But a 2017 study counted roughly 101 vog days a year reaching Oahu, arriving in about 57 separate events that typically lasted one to two days apiece. The riskiest setup is a pre-frontal Kona wind ahead of an approaching cold front, when the trades die, an inversion layer settles low, and southerly winds carry the vog plume back up the island chain into Honolulu and the Ewa side, including Pearl City.
The clearest recent example was the 2018 Lower Puna eruption, when Kilauea's sulfur dioxide output jumped from a baseline of roughly 1,500 to 2,500 tons a day to as much as 40,000 tons on its worst day, May 30, 2018. Oahu felt it: the EPA stood up a 35-monitor tracking network that June, and a University of Hawaii economic study the same year found emergency-room visits for breathing problems rose 23 to 36 percent during vog events. It's a reminder that Pearl City's air can turn hazy without a single local source doing anything different — the volcano is doing the polluting from across the ocean.
Dry-season brush fires add smoke of their own
Pearl City's dry season, roughly May through October, is also brush-fire season in the grasslands just west of town. In August 2025, a fire burned through more than 250 acres near Kunia Camp, bordering Waipahu, which shares Pearl City's western edge, and a second blaze the same month burned about 600 acres nearby and briefly closed Kunia Road. Hawaii's Department of Land and Natural Resources warned that smoke could linger for days or even weeks as smoldering stumps kept burning after the flames were out.
The fuel is invasive guinea grass, which the state's own invasive species program rates as a high fire risk: it grows fast, dries out completely between rains on the leeward side, and regrows even thicker after a burn. None of this reaches Pearl City's rooftops directly, but it sits close enough that a dry, windy afternoon in Kunia or Waipahu can put a haze over the Pearl Harbor side of town before anyone smells smoke.
Pearl City air quality FAQ
What is the air quality in Pearl City right now?
As of September 14, 2026 at 5:09 AM PDT, the air quality in Pearl City, Hawaii is AQI 1 — Good — with PM2.5 at 0.1 µg/m³, the median of 4 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Why does vog sometimes reach Pearl City?
Pearl City is normally shielded from Kilauea's volcanic haze by steady northeast trade winds, which carry the plume toward the Big Island's Kona coast instead. But when the trades weaken or reverse into a southerly Kona wind, usually ahead of a winter cold front, the vog can drift back up the island chain and settle over leeward Oahu, including Pearl City. A 2017 study counted roughly 101 such vog days a year on Oahu.
Does Pearl City get wildfire smoke?
Not from forest fires, but from brush fires in the dry grasslands nearby. In August 2025, fires burned more than 250 acres near Kunia and about 600 acres in a separate blaze close to Waipahu, right on Pearl City's western border, with officials warning smoke could linger for days afterward. Central and leeward Oahu's dry season, roughly May through October, is when that risk is highest.
What the AQI numbers mean
| AQI | Category | What it means for you |
|---|---|---|
| 0–50 | Good | Open the windows. Great for outdoor activity. |
| 51–100 | Moderate | Sensitive groups may want to take it slower outside. |
| 101–150 | Unhealthy for Sensitive Groups | Kids, elderly, and respiratory conditions stay closer to home. |
| 151–200 | Unhealthy | Skip outdoor exercise. Close windows. |
| 201–300 | Very Unhealthy | Limit time outside. N95 if you must go. |
| 301+ | Hazardous | Health emergency. Stay inside, run filtration if you have it. |
Canairy lets you tighten these bands if you’re more sensitive than the EPA default, so an alert can fire before the official category changes. How to read the Air Quality Index
Where these readings come from
The AQI at the top of this page is the median of the 4 curated PurpleAir sensors Canairy tracks in and around Pearl City, with outliers set aside so that one sensor brought indoors — or parked beside a barbecue — cannot set the number for a whole city. Every sensor behind it is listed above with its distance and bearing from the city center. There is no black box here.
In the app, a place you save resolves the same way first. When no neighborhood sensor is reporting it falls back to the nearest EPA AirNow monitor, and anything modeled rather than measured is labelled a regional estimate rather than passed off as a sensor reading. How low-cost sensors compare to regulatory monitors
About Canairy
Canairy is free to download. The free plan covers one saved place with live readings, a plain-English verdict, and push alerts when the air crosses a threshold you choose. Paid plans add more places, faster refreshes, and SMS alerts. It is built by two parents in Sonoma County, California, who got tired of guessing whether it was safe to send the kids outside. Why we built it
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Air quality near Pearl City
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