Heat and bad air hit Maryland on Fourth of July

Marylanders heading out for Fourth of July celebrations Saturday are dealing with dangerous heat and poor air quality across much of the state.

What’s Happening: The National Weather Service has issued an Extreme Heat Warning for parts of north central Maryland, including Frederick County, running from 10 a.m. to 8 p.m. Saturday. Heat index values — what the temperature actually feels like when humidity is factored in — are expected to reach between 105 and 108 degrees.

What’s Important: Overnight low temperatures in the 70s gave little relief heading into Saturday morning. The heat is not expected to let up quickly — heat index values of 95 to 100 are possible again Sunday afternoon.

Air Quality: The Maryland Department of the Environment has issued air quality alerts covering most of the Baltimore and Washington metro areas:

• Prince George’s County, central and southeast Montgomery County, and central and southeast Howard County are under a Code Red alert, meaning air pollution levels are unhealthy for the general public.
• Northern Baltimore County, northwest Harford County, southern Baltimore County, and Anne Arundel County are under a Code Orange alert, meaning pollution may be unhealthy for sensitive groups, including children, the elderly, and people with asthma, heart disease, or other lung conditions.

How This Affects Real People: Officials recommend staying indoors in air conditioning, drinking plenty of fluids, avoiding direct sun, and checking on neighbors and relatives. Anyone who does go outside should avoid strenuous activity or exercise.