I'm an EPA worker who's responded to more than 100 toxic spills and chemical fires, and I'll never forget one that got my adrenaline going

• Brian Kelly is among the 220 emergency responders at the Environmental Protection Agency.
• He responds when there's a major spill or chemical fire, including after train derailments.
• Kelly worked on disasters like the BP oil spill and lead drinking-water crisis in Flint, Michigan. 

This as-told-to essay is based on a conversation with Brian Kelly, an on-scene coordinator at the Environmental Protection Agency. It's been edited for length and clarity.

I'm one of the 220 emergency responders that the EPA has across the country who's on call when there's a major oil spill or chemical fire, like after the train derailment in East Palestine, Ohio.