Washington, D.C., and the surrounding area were placed under a “Code Red” air quality alert on Sunday after a record-breaking Independence Day fireworks display filled the skies over the nation’s capital.

District officials issued the alert early Sunday morning, just hours after the massive fireworks show concluded late Saturday night. According to AlertDC, a Code Red designation indicates that air quality reached unhealthy levels for sensitive groups, including older adults, children, and people with certain medical conditions. Officials advised those residents to limit time outdoors while the alert remained in effect.