Los Angeles Times: unhealthy air across SoCal

South Coast Air Quality Management District said a wildfire smoke advisory remained in effect through 10 p.m. on Thursday, May 21, for broad stretches of Southern California as smoke from the Sandy, Bain, Verona and Santa Rosa Island fires spread across the region. PM2.5 pollution reached the “Unhealthy for Sensitive Groups” category at times in the San Fernando Valley, central Los Angeles, Jurupa Valley, the Perris-Hemet area and Diamond Bar, the agency said. Los Angeles County health officials separately warned that smoke from the Sandy fire could reach from the San Fernando Valley to Arcadia, while smoke already over the ocean from the Sandy and Santa Rosa Island fires was expected to move back onshore overnight. ### Which fires were driving the smoke? The South Coast AQMD advisory named four fires on May 21: the Sandy fire near Simi Valley in Ventura County, the Bain and Verona fires in Riverside County, and the Santa Rosa Island fire in Channel Islands National Park. In its Thursday advisory, the district said the Sandy fire had burned 1,698 acres and was 15% contained, while the Santa Rosa Island fire had burned 16,942 acres and was 26% contained. Widespread moderate smoke impacts were forecast across the Los Angeles Basin, Catalina Island, the Inland Empire and the Coachella Valley. (xappp.aqmd.gov) KTLA, citing Los Angeles County public health officials, reported that unhealthy air from those fires was affecting parts of Ventura, Los Angeles, Orange, Riverside and San Bernardino counties. The station said the smoke advisory covered the day on Thursday. ### Why were officials watching the Sandy fire so closely? The Ventura County Fire Department said Wednesday evening that air quality monitoring was underway around the Sandy fire perimeter because of the blaze’s proximity to the Santa Susana Field Laboratory. (xappp.aqmd.gov) CAL FIRE said monitoring equipment had been deployed proactively to establish background readings and assess conditions if the fire moved farther into the area. The Santa Susana Field Laboratory is the former nuclear and rocket testing site above Simi Valley that has long drawn scrutiny over contamination. (ktla.com) Secondary reports based on Los Angeles Times reporting said firefighters were working to keep flames away from the site while officials tracked whether any contaminants could be released. ### What was happening on Santa Rosa Island? National Parks Traveler reported on May 20 that the Santa Rosa Island fire had grown past 16,000 acres after a stranded sailor used an emergency flare when his sailboat grounded on the island. (latimes.com) The publication said the island was closed to the public and that firefighters had begun to slow the fire’s spread as winds improved, with containment at 26% as of Wednesday morning. (aol.com) By Thursday, later reports said the blaze had burned nearly a third of the island and containment was approaching 50%. CBS Los Angeles said the fire remained 44% contained as of Wednesday evening, and the Santa Barbara Independent reported on Thursday morning that the fire was more than 17,000 acres and 44% contained. ### What were residents and schools told to do? (nationalparkstraveler.org) Los Angeles County health officials said people who could see or smell smoke, or notice ash in the air, should stay indoors to limit exposure. The county said children, older adults, people with heart or lung disease and immunocompromised residents faced higher risks from smoke exposure. County officials also asked schools and recreation programs in smoke-affected areas to review California wildfire-smoke guidance, including whether to limit or suspend outdoor physical education and after-school sports until conditions improved. (cbsnews.com) The AQMD said residents could track neighborhood conditions on its air-quality map as fire activity and winds changed. The Thursday smoke advisory was scheduled to expire at 10 p.m. on May 21, according to South Coast AQMD and Los Angeles County public health officials. (ktla.com) CAL FIRE incident pages for the Sandy fire and Santa Rosa Island fire were expected to carry the next containment and acreage updates, while AQMD said local air readings could change quickly with weather and fire behavior. (xappp.aqmd.gov)