LOS ANGELES (CBSLA) — The use of legal and illegal fireworks around Southern California on the Fourth of July brought the worst air quality the region has seen in a decade, the South Coast Air Quality Management District reported Wednesday.

Illegal Fourth of July fireworks, like the one seen here in MacArthur Park, created hazardous air quality for the Southland, regulators said. (Credit: Alicia Ramirez)

According to AQMD, concentrations of particulate matter were 70% higher than previous years between the hours of 7 p.m. July 4 and 7 a.m. the following day in the South Coast Air Basin — which includes Orange County and parts of Los Angeles, Riverside and San Bernardino counties.

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In L.A. and Orange counties, AQMD said air quality reached “very unhealthy” and “hazardous” levels, with dry air during the weekend helping to trap pollution.

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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,” AQMD said in an advisory issued ahead of the holiday weekend.

The highest concentrations of particulate matter were detected in Central Los Angeles, North Hollywood and Anaheim. Officials said some instruments had so much residue on them that they would not accurately collect data.

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(© Copyright 2020 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)