5:18 PM GMT
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Live updates as wildfire smoke prompts air quality alerts across Philadelphia region
Last updated: Thursday, July 16, 2026 10:48PM GMT
PHILADELPHIA (WPVI) -- Heavy smoke from wildfires is darkening skies from the U.S. Midwest to the East Coast. The smoke on Thursday prompted warnings that breathing the air outside could be dangerous for people.
The smoke is coming from fires that are burning primarily in Canada but also in northern Minnesota. A National Weather Service Meteorologist in Detroit says a lingering high pressure system has trapped the smoke close to the ground.
Air quality alerts have been issued in Philadelphia, Pennsylvania, New Jersey and Delaware.
Follow along for live updates.
Key Headlines
- 2 hours and 11 minutes ago
- 5:18 PM GMT
- 4:07 PM GMT
- 4:18 PM GMT
Here's how the news is developing.
Jul 16, 2026, 10:48 PM
Latest AccuWeather forecast on air quality and extreme heat
THURSDAY: Smoke in our region has dropped air quality to unhealthy levels for all.. Please limit outdoor activities to prevent yourself from breathing in harmful particulates. Another hot day as heat wave #5 rolls on, high 92, and humid. Watch for an isolated storm to pop up that could be gusty.
FRIDAY: We again could see smoke reducing visibility and creating air quality issues. Clouds mix with sunshine, high 90.
Get the latest AccuWeather forecast at 6abc.com/weather.
4:18 PM GMT
NJ DEP issues air quality advisory
4:07 PM GMT
Air Quality Index: What do the numbers mean?
The Air Quality Index is a scale used for daily reporting of how clean or polluted the air is, and what health effects might be of concern.
The AQI focuses on what you might experience if exposed within a few hours or days after breathing polluted air.
The Environmental Protection Agency calculates the AQI using 5 major air pollutants regulated by the Clean Air Act:
- Ground-level ozone
- Particle pollution (also known as particle matter)
- Carbon monoxide
- Sulfur Dioxide
- Nitrogen Dioxide
AQI BY THE NUMBERS
The AQI runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern.
The index is divided into six categories, each corresponding to a different level of health concern.
An AQI of over 100 triggers an alert for vulnerable groups.
Levels over 300 signal a health emergency and everyone is more likely to be affected.
Full breakdown:
Green - Good: 0 to 50. Air quality is satisfactory, and air pollution poses little or no risk.
Yellow - Moderate: 51 to 100. Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
Orange - Sensitive Groups: 101 to 150. Members of sensitive groups may experience health effects. The general public is less likely to be affected.
Red - Unhealthy: 151 to 200. Some members of the general public may experience health effects; members of sensitive groups may experience more serious health effects.
Purple - Very Unhealthy: 201 to 300. Health alert: The risk of health effects is increased for everyone.
Maroon - Hazardous: 301+. Health warning of emergency conditions: everyone is more likely to be affected.
Learn more about the index from the EPA at AirNow.gov.
6abc Air Quality Tracker
