Air Quality in Roseville, California — Live

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

Live Roseville AQI from nearby PurpleAir sensors loads when this page opens in a browser, along with a live sensor map covering Roseville and Rocklin, Citrus Heights, Granite Bay, Lincoln.

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.

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.

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

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.

What is the air quality in Roseville right now?

This page shows the live AQI for Roseville, calculated from PurpleAir sensors around the city and updated continuously. Placer County's own regulatory network is five stations covering everything from the valley floor to Tahoe, so neighbourhood sensors fill in a lot of ground the official monitors cannot. That matters more than usual in a city built around a four-mile rail corridor, where conditions a mile apart are genuinely not the same.

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 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.