California Fire Live Updates: New Fire Breaks Out Along Highway 405 in Brentwood

The Hughes Fire emitted huge plumes of smoke as it grew rapidly in the Castaic area, leading to potentially unhealthy air quality nearby, officials said.

The smoke caused the air quality index to fall into the unhealthy range in Camarillo, Fillmore, Moorpark, Oxnard, Piru, Santa Paula, Simi Valley and Ventura, according to the Ventura County Air Pollution Control District .

Air quality monitors downwind of the Hughes Fire recorded dangerous levels of smoke and soot, according to the district. Some of the highest levels were recorded at Rio Mesa High School in El Rio, just north of Oxnard.

The local air district urged residents to stay indoors as much as possible, close all windows and doors and wear protective masks to limit their exposure.

The South Coast Air Quality Management District also issued a smoke advisory for a large portion of northwest Los Angeles County. The potentially affected area extends from the coastline of Santa Monica and Malibu south, through the San Fernando Valley, Santa Clarita, Angeles National Forest and the Castaic Lake area.

Smoke will have the most impact on areas near and southwest of the fire, including the San Gabriel Mountains, the Interstate 5 corridor near Castaic Lake and Santa Clarita, according to AQMD.

Children, the elderly and pregnant women are particularly vulnerable to the effects of smoke and soot. When ultrafine particles from wildfires are inhaled, they travel into the lungs and even the bloodstream, where they can trigger respiratory and cardiovascular problems.