Air Quality in Roseville, California — Live
Live readings from PurpleAir sensors across Roseville — with free alerts the moment the air turns.
AQI 13 from 5 PurpleAir sensors · Holding steady · data from PurpleAir
As of , the air quality in Roseville, California is AQI 13 — Good and holding steady — with PM2.5 at 2.4 µg/m³, the median of 5 live PurpleAir sensors reading 7 to 19. 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 Roseville: weeds pollen is the strongest of the three at a low 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 Roseville and Rocklin, Citrus Heights, Granite Bay, Lincoln. Every dot is a real sensor, color-coded by current air quality.
Sensor by sensor in Roseville
The sensors Canairy reads in Roseville agree right now — all 5 sit in the Good band, a 12-point spread — so the city-wide number is a fair description of the whole area today.
| From city center | AQI | Category |
|---|---|---|
| 3.4 mi S | 19 | Good |
| 4.7 mi WNW | 13 | Good |
| 7.3 mi E | 8 | Good |
| 7.9 mi SE | 14 | Good |
| 9.3 mi SE | 7 | Good |
Roseville has a pollution source most cities its size do not: a rail yard in the middle of it. Union Pacific's J.R. Davis Yard occupies about 950 acres on a strip a quarter of a mile wide and four miles long that runs alongside Interstate 80, bounded by commercial, industrial and residential property. It is the largest locomotive service and maintenance yard in the West, with over 30,000 locomotives visiting each year, and in 2004 the California Air Resources Board published a full health risk assessment of the diesel exhaust coming off it. That study, and what Placer County did about it afterwards, is the part of Roseville's air story you will not find anywhere else in the region.
What Canairy does for Roseville
A clear verdict
Not just a number — a plain-English call for Roseville: open the windows, or keep them shut.
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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.
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What the Air Resources Board found at the rail yard
The Placer County Air Pollution Control District asked the state to look at the yard after years of complaints from residents whose homes had crept closer to it. The report, released on 14 October 2004, estimated that locomotive operations at the yard emitted about 25 tons of diesel particulate matter in the year 2000. Roughly half of that came from moving locomotives, about 45 percent from idling ones, and around 5 percent from engine testing. Modelling put the estimated lifetime cancer risk above 500 in a million across an area of 10 to 40 acres northwest of the Service Track and the Hump and Trim areas. Risk between 100 and 500 in a million covered roughly 700 to 1,600 acres where 14,000 to 26,000 people lived, and risk between 10 and 100 in a million covered 46,000 to 56,000 acres with a population of 140,000 to 155,000.
That was two decades ago and it did not simply sit there. Both the county district and the state signed agreements with Union Pacific to cut emissions from the yard, with the 2004 agreement targeting at least a 10 percent reduction in particulate emissions by the end of 2007 against a baseline year. A four-year monitoring project ran from 2005 to 2008, and the final report in December 2009 concluded the mitigation goals had been met. A supplemental study in 2007 found the particles being collected were in the very fine to ultra-fine size range and carried a higher concentration of polycyclic aromatic hydrocarbons than diesel truck exhaust does. The district's own guidance for people with respiratory conditions living near the yard is to use indoor air filtration.
Foothill fires reach Roseville before they reach the rest of the valley
Placer County runs from Roseville up to Lake Tahoe, and more than 550,000 acres of it is heavily forested Sierra Nevada foothill and mountain country. Roseville is the valley-floor end of that, which means fires burning up the hill send their smoke down onto the city. The Mosquito Fire is the clearest recent example. It started on 6 September 2022 near Foresthill in the Tahoe National Forest, and by 9 September it had burned 29,585 acres at zero containment, prompting Placer and El Dorado counties to issue a joint air quality advisory for smoke. That advisory was extended twice, first through 12 September and then through 16 September. The fire was finally contained on 22 October at 76,788 acres across both counties, having destroyed 78 structures.
Placer County operates five permanent air monitoring stations — Auburn, Colfax, Lincoln, Roseville and Tahoe City — each measuring ozone and PM2.5 year-round. Five stations across a county that stretches from the valley floor to the Sierra crest is a coarse net for a smoke plume that can drop into one neighbourhood and skip the next, which is the case for watching sensors on your own street alongside the official numbers.
Summer ozone is made somewhere else and delivered here
Roseville's warm-season ozone is largely not Roseville's doing. The Sacramento region's ozone peaks downwind of the city rather than over it: the Sacramento air district designates its Folsom monitor, about twenty miles northeast of downtown Sacramento, as the county's maximum summertime ozone site specifically for days with prevailing afternoon southwesterly winds. Roseville sits on that same northeastern side of the metro, at the point where the valley starts tilting up into the foothills. Ground-level ozone reaches its highest levels in the afternoon and early evening, and almost entirely in summer.
There is real progress underneath that. The Sacramento Federal Nonattainment Area, which includes Placer County, was designated severe nonattainment in 1997 and stayed there for decades. It met the 2008 federal eight-hour ozone standard of 75 parts per billion by its 2024 attainment deadline, and the achievement was marked in August 2025. That is a regional average over years, not a promise about a specific July afternoon, but it is the direction of travel.
Roseville air quality FAQ
What is the air quality in Roseville right now?
As of September 10, 2026 at 5:10 AM PDT, the air quality in Roseville, California is AQI 13 — Good — with PM2.5 at 2.4 µg/m³, the median of 5 live PurpleAir sensors. Open the windows. Great for outdoor activity.
Why is there smoke in Roseville today?
From late summer into autumn the usual answer is a fire in the Sierra foothills or mountains east of here — Placer County runs from Roseville all the way to Lake Tahoe, so a fire near Foresthill or Colfax puts smoke over the city without ever threatening it. That is what happened during the Mosquito Fire in September 2022, when Placer and El Dorado counties ran a joint smoke advisory for well over a week. In winter, low-lying smoke on a cold, still evening is more likely to be residential wood burning. If the haze is thin, odourless and even across the whole sky on a hot afternoon, it is more likely ozone-season smog than smoke.
Does the Union Pacific rail yard still affect Roseville's air?
The 2004 state study is the last full public health risk assessment of the yard, and a great deal has changed since: Union Pacific agreed with Placer County and the state to cut particulate emissions, a four-year monitoring project ran from 2005 to 2008, and the December 2009 final report concluded the mitigation targets had been met. Cleaner locomotive engines have come into service across the fleet since then as well. What has not changed is the geography — a 950-acre yard on a strip a quarter mile wide and four miles long, running through the middle of town beside Interstate 80. Diesel particulate concentrations are always highest close to concentrated sources like rail yards, ports and freeways, so proximity still matters.
Is Roseville's air worse than Sacramento's?
Not as a general rule, and the two cities do not have the same problem. Sacramento's difficulty is the valley bowl holding smoke and winter wood smoke in place over a large population. Roseville's specifics are different: a large diesel rail facility running through the middle of it, and a position on the foothill edge where smoke from Sierra fires arrives early. On a normal day both cities are usually fine. The value of watching a nearby sensor is knowing which of those specific things is happening on your street on the day it happens.
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 5 curated PurpleAir sensors Canairy tracks in and around Roseville, 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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