Chemical and hazmat emergencies kill and injure through inhalation, skin contact, and contamination of food and water. Unlike most natural disasters, the correct survival action for a chemical emergency — shelter-in-place or evacuate — depends entirely on the specific chemical and your location relative to it. This guide covers the identification and decision framework used by first responders, adapted for civilian use.
Hazmat Incident Types and Common Sources
- Transportation accidents: The most common type. Tank trucks, rail cars, and pipelines carry chemicals through residential areas. A single chlorine rail car contains enough gas to be dangerous for miles downwind.
- Industrial facility releases: Chemical plants, water treatment facilities (large chlorine storage), and manufacturing operations near residential areas. Most counties have a Local Emergency Planning Committee (LEPC) database of facilities with hazardous materials — available publicly.
- Pipeline incidents: Natural gas, petroleum, and increasingly, liquid chemical pipelines. Gas leaks are immediately detectable by smell (added mercaptan odorant); liquid chemical leaks may not be.
- Industrial and structure fire smoke: Industrial structure fires, vehicle fires, and fires in areas with chemical storage produce smoke that is qualitatively more toxic than wildland fires. N95 masks are inadequate for most toxic industrial smoke — distance is the primary protection.
DOT Hazmat Placard Identification
Every vehicle carrying hazardous materials in the US is required to display DOT placards — diamond-shaped signs indicating the hazard class. Understanding placards gives you immediate information about the threat:
- Orange (Explosives): Subdivision 1.1–1.6; immediate explosive hazard. Evacuate; do not approach.
- Red (Flammable Gas/Liquid): Classes 2.1 and 3. Fire and explosion risk. Evacuation distances depend on the material; look up the UN number in the ERG.
- Green (Non-Flammable Gas): Class 2.2. May be asphyxiant (oxygen-displacing) or toxic depending on UN number.
- White with skull (Toxic): Class 6.1. Toxic by inhalation, ingestion, or skin contact. Shelter or evacuate based on release size and wind direction.
- Yellow (Oxidizer): Class 5.1. Accelerates combustion of other materials. High fire hazard; evacuate.
- UN number (4-digit number on placard or orange panel): Identifies the specific chemical. Look up in the Emergency Response Guidebook (ERG) — available as a free PDF from PHMSA and as the free ERG app.
CHEMTREC (Chemical Transportation Emergency Center): 1-800-424-9300 — 24-hour hotline providing emergency response guidance for chemical incidents. Primarily for first responders but available to anyone during an emergency.
Shelter-in-Place vs. Evacuation: The Decision
The correct action depends on the chemical’s properties and your situation:
- Shelter-in-place is preferred when: The release is temporary (one-time spill, not ongoing); you cannot safely move upwind and uphill; authorities direct shelter-in-place; the chemical is a heavy gas that concentrates near ground level (chlorine, hydrogen sulfide) and your upper floors provide better protection than the outdoors.
- Evacuation is preferred when: You are directly downwind of a large, ongoing release; authorities order evacuation; you can quickly move to a vehicle and escape perpendicular to the plume.
General rule for chemical plumes: Ready.gov says to move away immediately, upwind of the source. If going upwind would take you through the release, move crosswind (perpendicular to the wind) to get out of the plume first, then keep moving away. Moving straight downwind keeps you in the plume.
Creating a Sealed Safe Room
For shelter-in-place, a sealed interior room reduces chemical infiltration by reducing air exchange with the outside. Ready.gov gives no time limit for a sealed room: stay until authorities say it is safe, and keep a radio on so you hear the all-clear as soon as it comes.
Safe room setup:
- Choose an interior room above ground level (most heavy gases are denser than air and concentrate near the ground)
- Pre-cut plastic sheeting (4–6 mil polyethylene) to cover all vents, windows, and the door of the chosen room; store with duct tape in the room
- Seal gaps around the door with duct tape from the inside; lay a wet towel at the base of the door
- Turn off HVAC — air handling systems draw outside air in and distribute chemical throughout the structure
- Have a battery-powered radio to monitor emergency broadcast and “all clear” signal
What to buy ahead: One roll of 6-mil polyethylene sheeting (10×50 feet) and 2 rolls of duct tape covers one safe room.
Respiratory Protection for Civilians
For most toxic chemical emergencies, civilian respiratory protection options are limited:
- N95 respirator: Filters particles but does not filter chemical vapors or gases. Provides minimal protection against chlorine, ammonia, hydrogen sulfide, or other toxic gases. Only useful for particulate releases (dust, some smoke).
- Full-face respirator with combination cartridges (3M 6800 + 60926 cartridges): Filters both particles and common industrial gases. 3M lists the 60926 for ammonia, chlorine, certain organic vapors, formaldehyde, hydrogen sulfide and several acid gases. It is not listed for hydrogen cyanide, and it is not for atmospheres immediately dangerous to life. Must be fit-tested for effectiveness.
- A wet cloth over the nose and mouth: Provides minimal, brief protection against some water-soluble chemicals (chlorine dissolves in water; a wet cloth briefly reduces intake). Not a substitute for evacuation or shelter.
Decontamination After Chemical Exposure
If you were exposed to an unknown chemical or confirmed toxic substance:
- Remove clothing immediately: Taking off your clothes removes 80% to 90% of the chemical (CDC). Cut clothing off rather than pulling over head (avoids face exposure). Place in a bag away from people.
- Wash and flush: CDC says to wash from head to feet with lukewarm water and mild soap for at least 2 to 3 minutes, without scrubbing. Flush burning eyes with water for 10 to 15 minutes, and do not use eyedrops.
- Do not induce vomiting for ingested chemicals unless explicitly instructed by Poison Control (1-800-222-1222) — some chemicals cause additional damage on the way back up.
- Seek medical care: Even if you feel well immediately after exposure, many chemicals have delayed effects. Report the exposure to emergency personnel.
Know Your Local Hazards: The LEPC Database
Most communities are served by a Local Emergency Planning Committee (LEPC) that maintains a list of facilities with significant quantities of hazardous materials. Under the Emergency Planning and Community Right-to-Know Act (EPCRA), this information is publicly available. Search “[your county] LEPC hazardous materials” to find facilities near your home and the chemicals they store. This tells you which direction to evacuate if a specific facility has an incident.
Where to Go Next
Respiratory protection for wildfire smoke (a related particulate hazard) is covered in wildfire evacuation: defensible space, go/no-go decision, and evacuation kit. Emergency shelter-in-place supply requirements overlap with general extended outage preparation in extended power outage: grid-down preparedness for 14-day blackout.
