Air Quality in Gresham, Oregon — Live

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

Live Gresham AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Gresham and Troutdale, Fairview, Wood Village, Portland.

Gresham sits at the eastern edge of the Portland metro, immediately south of Troutdale, where the Columbia River Gorge opens out onto the valley floor. That position is most of the story of Gresham's air. The gorge runs more than eighty miles and cuts up to 4,000 feet deep through the Cascades, and when high pressure builds on the dry side of the mountains, air is squeezed through it and arrives here first. Sometimes that east wind is just cold. Sometimes it is carrying ash.

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.

Gresham is where the east wind lands first

The Columbia River Gorge ends at the eastern reaches of the Portland metro, passing right by Troutdale, which borders Gresham on the north. The pressure difference between the dry east side of the Cascades and the wet west side turns that cut in the mountains into a wind tunnel, and the winds it produces reach the west end as strong easterlies. Troutdale is known for some of the windiest conditions in the Pacific Northwest — enough that local businesses have taken to putting East Wind in their names.

You can see the gradient in an ordinary forecast. During a windstorm in early February 2026 the National Weather Service put the strongest gusts from Washougal and Troutdale eastward, with Corbett already gusting over 60 mph that morning, and forecasters warned it would be very breezy out in east Multnomah County — the part of the county Gresham sits in — while the west side of the metro stayed comparatively calm. The same corridor draws very cold east winds toward the mouth of the gorge in winter, which is where the region's snow and freezing-rain events come from.

The 2017 Eagle Creek Fire was a local event out here

The fire started on September 2, 2017, when a teenager threw fireworks into Eagle Creek Canyon during an active burn ban. It went on to burn about 50,000 acres of the gorge and closed Interstate 84 from Troutdale to Hood River for weeks. Mt. Hood Community College in Gresham was the meeting point for evacuating residents, and on September 5 the Multnomah County Sheriff's Office issued Level 1 evacuation alerts for part of Troutdale, just up the road.

Smoke and up to an inch of ash fell across the Portland area on September 4 and 5, and it did not fall evenly. One account from those days described readings that ran from unhealthy in Gresham to moderate out in Beaverton on the same afternoon. That east-to-west gradient is the practical reason a metro-wide number is not much use if you live on this side of town.

In winter, the smoke is usually somebody's chimney

Oregon DEQ is direct about what drives fine-particle pollution across the Portland region: the primary source of PM2.5 is woodstoves, with cars, backyard burning, industry and commercial activity contributing on top of that. Cold snaps in Gresham are often east-wind snaps, and once the wind drops and a temperature inversion settles over the valley floor, that wood smoke stays down where people are breathing it.

DEQ names two criteria pollutants as the ones of most concern in the Portland area: ozone and fine particulate matter. They run on opposite calendars. Ozone builds on hot, sunny afternoons out of traffic and industrial emissions; fine particles peak on cold, still nights. A page that only watches one of them will tell you the air is fine half the year when it isn't.

Gresham air quality FAQ

Why is there smoke in Gresham today?

Check the wind direction first. Gresham sits near the west end of the Columbia River Gorge, so when the flow turns easterly it delivers whatever is burning upriver before the rest of the metro notices. That is how the 2017 Eagle Creek Fire dropped ash and unhealthy air on east Multnomah County. If nothing is burning, a smoky evening in winter is most likely wood stoves and fireplaces — Oregon DEQ names woodstoves as the primary source of fine-particle pollution across the Portland region, and an inversion over the valley floor keeps that smoke from clearing.

What is the air quality in Gresham right now?

This page shows the current AQI for Gresham, calculated from PurpleAir sensors around the city and updated continuously. The map below shows every live sensor, so you can look at the reading nearest your own street rather than an average for the whole metro.

Does Gresham really get different air than the rest of Portland?

On some days, yes, and the geography is why. Gresham is at the eastern edge of the metro next to the mouth of the Columbia River Gorge, so east winds and anything they carry arrive here before they reach Beaverton or Hillsboro. During the Eagle Creek Fire in September 2017 one report of the same afternoon had Gresham reading unhealthy while Beaverton was still moderate. On calm days the difference largely disappears.

What is an east wind event and why does it matter for air quality?

It is what happens when high pressure builds east of the Cascades and air pours west through the gorge toward the lower pressure on this side. The gorge acts as a wind tunnel, so the flow comes out fast and dry at the west end near Troutdale and Gresham. In winter those winds bring the cold air behind most of the region's snow and freezing rain. In late summer the same setup is what pushes wildfire smoke from the Cascades and the gorge directly over east Multnomah County.

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.