Wildfire smoke has been rushing into the U.S. like an avalanche. Seen on satellites, it looks like an unstoppable force(opens in a new...

Wildfire smoke has been rushing into the U.S. like an avalanche. Seen on satellites, it looks like an unstoppable force(opens in a new tab).Now that the thick smoke — filled with tiny particles that are unhealthy to breathe — is blanketing different regions and heavily-populated areas, you'll likely want to know how bad the air is, and what air quality ratings mean.Crucially, you'll also want to seek guidance from your local public health agencies. For example, on June 8 the Philadelphia Department of Public Health advised residents(opens in a new tab) in the smoky city to "Avoid going outdoors as much as possible." SEE ALSO: When will the Canada wildfire smoke clear? Not as soon as...

Wildfire smoke has been rushing into the U.S. like an avalanche. Seen on satellites, it looks like an unstoppable force(opens in a new tab).Now that the thick smoke — filled with tiny particles that are unhealthy to breathe — is blanketing different regions and heavily-populated areas, you'll likely want to know how bad the air is, and what air quality ratings mean.Crucially, you'll also want to seek guidance from your local public health agencies. For example, on June 8 the Philadelphia Department of Public Health advised residents(opens in a new tab) in the smoky city to "Avoid going outdoors as much as possible." SEE ALSO: When will the Canada wildfire smoke clear? Not as soon as...