An aerial view of crews attempting to extinguish a large fire and explosion that occurred at the Chevron Refinery in El Segundo overnight Thursday. The explosion and hours-long fire at Chevron’s refinery Thursday night in El Segundo deeply unnerved communities in the South Bay. AdvertisementBut, for the Chevron refinery explosion, there is no guarantee such an investigation will take place. Environmental advocates say the extent of the fallout may not be known until there is a larger examination of air quality monitors. OSHA records show the agency conducted at least 15 inspections at the Chevron refinery in El Segundo over the last decade, identifying 17 violations.