The use of legal and illegal fireworks around Southern California brought the worst air quality to the region in a decade, the South Coast Air Quality Management District reported Wednesday.
Concentrations of PM2.5 were 70% higher than previous years between 7 p.m. on the Fourth of July and 7 a.m. the next day in the South Coast Air Basin, which includes Orange County and parts of Los Angeles, Riverside and San Bernardino counties, according to the AQMD.
Air quality reached "Very Unhealthy" and "Hazardous" levels in parts of Los Angeles and Orange counties. Dry air during the weekend trapped the pollution, adding to the high levels.
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"Breathing fine particulate matter can lead to a wide variety of cardiovascular and respiratory health effects such as heart attacks, asthma aggravation, decreased lung function, coughing or difficulty breathing and may lead to premature death in people with heart of lung disease," according to an AQMD statement.
The highest concentrations of PM2.5 were detected in Central Los Angeles, North Hollywood and Anaheim, and some instruments had so much residue on them that they could not accurately collect data, according to the pollution control agency.