Thousands of residents in parts of Florida and Oregon have been warned to stay inside as the amount of fine particle pollution (PM2.5) in the atmosphere reached an “unhealthy” level on Tuesday as of 3 a.m. Eastern time, the Environmental Protection Agency’s (EPA) AirNow Map shows. 

Why This Matters

The EPA uses the Air Quality Index (AQI) to measure and communicate air quality across the United States. The AQI is a standardized scale from 0 to 500 that classifies pollution levels into six categories, ranging from “good” to “hazardous.” Higher AQI values indicate higher levels of pollution and greater health risks for people in the affected areas.

In this case, the AQI has classified the air pollution in parts of Florida and Oregon—including Orlando and La Pine, respectively—as “unhealthy” because of elevated levels of PM2.5. This means the levels of pollution could pose a health risk to all members of the public in the affected areas. 

The EPA said, “Even if you are healthy, you may experience temporary symptoms from exposure to elevated levels of particles.”

The agency considers PM2.5 to be one of the most dangerous forms of air pollution. This is because the particles are so fine—less than 2.5 micrometers in size—they can be easily inhaled, penetrating deep into the lungs and bloodstream, potentially worsening any lung or heart conditions. PM2.5 can also trigger mild to severe symptoms such as coughing; eye, throat, and nose irritation; chest tightness; and shortness of breath, making breathing difficult. 

Advice for Those Affected by ‘Unhealthy’ Air Quality 

The EPA advises people in sensitive groups—which include children, older adults and individuals with medical conditions such as asthma—to avoid long or intense outdoor activities when air quality reaches “unhealthy” levels. 

Everyone else should reduce the duration or intensity of outdoor activities until conditions improve. For example, choose to go for a walk rather than a run.

During long or intense outdoor activity, people breathe more deeply and more frequently, which increases the amount of PM2.5 they inhale. This can irritate the lungs and may trigger or worsen existing health conditions.

But it isn’t only outdoor air that’s affected by elevated PM2.5 levels.

Indoor air can also become polluted if these fine particles seep inside through open windows, doors or ventilation systems. 

The EPA suggests that those in affected areas should try to keep indoor air as clean as possible by using air purifiers or high-efficiency filters, keeping windows closed and avoiding activities that generate indoor pollution—such as burning candles, using wood‑burning stoves or lighting indoor fires—while the air quality is in the “unhealthy” range.

What Is Causing ‘Unhealthy’ Air Quality in Oregon, Florida? 

While the EPA hasn’t established the cause of the “unhealthy” air quality across parts of Florida and Oregon, PM2.5 can come from a variety of sources. 

These include dust from construction sites or unpaved roads, emissions from vehicles or industrial plants, or smoke from wildfires or smokestacks. 

Residents should monitor the AirNow Map and look out for updates from the EPA as air quality, like the weather, “can change from day to day or even hour to hour.”