These Counties Have MD's Worst Air Quality Thursday

MARYLAND — The air is still listed as unhealthy to breathe in most of Maryland Thursday afternoon, with 11 Maryland counties plus the city of Baltimore labeled as "Code Red" for poor air quality.

Health officials continue to warn children, the elderly, and those with respiratory conditions to stay indoors.

Smoke from millions of acres burning in eastern Canadian wildfires is lingering above several states on the East Coast this week, making it difficult to breathe and bringing an eerie yellow or gray sky. Smoke will become more dense in the region Thursday night, said forecasters.

As of Thursday afternoon, 20 of the state's 23 counties are under an air quality alert, along with the city of Baltimore. Much of the Baltimore-Annapolis-DC region started the day under Code Purple conditions, when the air is unsafe for everyone.

The Maryland Department of the Environment issued a Code Red alert for fine particulates in Baltimore city, plus Harford, Howard, Anne Arundel, Prince George's, Montgomery and Baltimore counties, along with adjacent counties.

Much of the Eastern Shore and southern Maryland are classified as Code Orange, meaning air is unsafe for the young, elderly and people with medical conditions.

Only Garrett and Allegany counties in far western Maryland were listed as moderate for air quality.

To see the current quality in your city or county check AirNow.gov.

Air quality alerts are triggered by a number of factors, including the detection of high levels of fine-particle pollution — known as "PM 2.5" — which can irritate the lungs.

The AQI scale is as follows:

• Good/green: 0-50
• Moderate/yellow: 51-100
• Unhealthy for sensitive groups/orange: 101-150
• Unhealthy/red: 151-200
• Very unhealthy/purple: 201-300
• Hazardous/maroon: 301-500

Here's a look at the air quality in some Maryland cities at 3:45 p.m. Thursday:

• Annapolis: 156
• Baltimore: 156
• Bel Air: 159
• Bethesda: 162
• Columbia: 162
• Bowie: 162
• Ocean City: 185
• Gaithersburg: 162
• Towson: 156
• Frederick: 77
• Westminster: 77

The highest concentrations of wildfire smoke should drop Thursday afternoon across Maryland, the Department of the Environment said, though particles in the air will remain a concern until Friday.

"Under northerly winds, smoke will continue to be pushed south over our area. Thicker smoke may overspread parts of the area Thursday morning, resulting in poor air quality and visibility potentially less than 2 miles," the National Weather Service said. "Some improvement is likely through the day, but the smoke likely will continue to affect the area at times until a front on Friday potentially brings some reprieve to fine particle concentrations."

Related: When Will The Smoke Clear In MD? Latest Forecast For Thursday

Friday's forecast calls for a chance of showers between 11 a.m. and 2 p.m., then a chance of rain and thunderstorms after 2 p.m. Widespread haze and patchy smoke will hang over the Baltimore region, the National Weather Service said. Look for partly sunny skies with a high near 78. Chance of precipitation is 50 percent.

Friday night rain chances drop to 20 percent, with a slight chance of showers and thunderstorms before 11 p.m. Widespread haze and patchy smoke are expected before 1 a.m.

Code Red means “unhealthy for the general population,” means everyone should keep outdoor activities light and short.

A Code Orange alert means that air pollution concentrations within the region are unhealthy for sensitive groups, including children, people with heart or lung disease, older adults, pregnant people, and those who spend a lot of time outdoors.

On Friday, levels of particulate matter in the air will still be high enough to impact those in sensitive groups, according to forecasters. Look to the weekend for the first signs of relief, as the NWS said "there should be some reprieve from the smoke through the weekend."