How Wildfires Changed Air Quality in America

The Scale of the Problem

The numbers tell a stark story. Using 10 years of EPA monitoring data (2014-2023), we can see wildfire smoke's fingerprint across the country:

• 123 western cities have PM2.5 as their dominant pollutant — wildfire smoke is the primary driver for many of these
• 125 western cities show worsening AQI trends, with fire-season PM2.5 spikes becoming more frequent and intense
• 161 eastern PM2.5 cities also show worsening trends, partly driven by long-range smoke transport

The EPA's own analysis confirms that without wildfire contributions, US PM2.5 levels would be at or near historic lows. Wildfire smoke has, in many regions, erased gains from decades of emission controls under the Clean Air Act.

Western Cities Hit Hardest

These western cities show the steepest air quality declines over the past decade, driven primarily by increasingly severe wildfire seasons:

Smoke Travels: East Coast Impact

The 2023 Canadian wildfire season demonstrated that wildfire smoke is not just a western problem. New York City, Philadelphia, and Washington DC all experienced AQI readings above 200 — the first time many eastern residents had ever checked an air quality app. Smoke plumes from fires in Quebec and Alberta traveled over 1,000 miles, blanketing the entire eastern seaboard in an orange haze.

This pattern is becoming more common. As fire seasons intensify and extend — driven by drought, heat, and decades of fire suppression — long-range smoke transport will increasingly affect cities that historically had little PM2.5 exposure.

Why Wildfires Are Getting Worse

Three converging factors are driving the increase in wildfire smoke:

1. Climate Change

Higher temperatures dry out vegetation faster, extending the fire season by weeks in many regions. The average US temperature has risen roughly 1.8°F since 1900, with the fastest warming in the West. Hotter, drier conditions create more fuel for fires and make them harder to contain.

2. Century of Fire Suppression

Decades of aggressive fire suppression have allowed fuel to accumulate in forests across the West. When fires do ignite in these overgrown forests, they burn hotter and larger than they would in a more natural fire cycle. Prescribed burns and forest thinning are being expanded, but cannot keep pace with the backlog.

3. Development in Fire-Prone Areas

The wildland-urban interface — where homes meet undeveloped land — has expanded dramatically. More people living in fire-prone areas means more ignition sources, more structures to protect, and greater health exposure when fires occur.

What You Can Do

If you live in a wildfire-prone area or anywhere smoke can reach:

• Monitor daily AQI through the EPA's Fire and Smoke Map
• Invest in a HEPA air purifier — the single most effective indoor protection during smoke events
• Create a clean air room — one sealed room with a purifier running for refuge during heavy smoke
• Use N95/KN95 masks outdoors during smoke events (cloth masks do not filter PM2.5)
• Check long-term trends on AirHistory before making relocation decisions