Air quality was poor in parts of Southern California Sunday due to Independence Day fireworks, according to the South Coast Air Quality Management District.
As of Sunday afternoon, the Air Quality Index levels were unhealthy in portions of Los Angeles and San Bernardino counties due to elevated fine particulate matter concentration, the AQMD said.
Overnight and in the morning hours, the level reached the hazardous category in parts of LA and Orange counties.
The decline in air quality was due to light winds and unregulated fireworks seen and heard around Southern California, the AQMD said. The levels were expected to drop to moderate levels in coastal and downtown LA areas, but the San Fernando Valley, San Gabriel Valley and Inland Empire were expected to have levels that were considered unhealthy for sensitive groups or generally unhealthy, according to the AQMD.
"Breathing of fine particular matter can lead to a wide variety of cardiovascular and respiratory health effects," the AQMD said. "Those with heath or lung disease, older adults and children are at greater risk and should consider reducing or avoiding outdoor physical activity, and prolonged or heavy exertion."