Chlorine
Chlorine is used to treat drinking water, pools and wastewater, to bleach paper and to make plastics and chemicals. As a gas it’s a powerful lung irritant. Most workers are more likely to meet it by accident, when bleach is mixed with another cleaner and releases chlorine or related gases.
- General Industry
- Water Treatment
- Cleaning
Know it when you see it
- Greenish-yellow gas with a sharp bleach-like smell
- Heavier than air, so it collects in low places like pits, basements, trenches and vaults
- Shipped and stored as a liquid under pressure in cylinders and ton containers; a small liquid leak becomes a large gas cloud
You can smell chlorine at low levels, but your nose gets used to it. Don’t rely on smell to tell you the air is safe.
Mixing dangers
- Bleach + acids (some toilet bowl, rust and drain cleaners) releases chlorine gas.
- Bleach + ammonia (glass cleaners, some degreasers, urine) releases chloramine gas.
- Pool chemicals mixed together or with water in the wrong order can react violently.
Use one cleaner at a time, follow the label, and rinse between products. See Household Chemicals.
Health effects
- Burning eyes, nose and throat; coughing; watery eyes
- Chest tightness, wheezing and shortness of breath
- At high levels, fluid in the lungs, which can show up hours later
- Liquid chlorine contact causes frostbite-like burns
Anyone with breathing trouble after an exposure needs medical care, even if they feel better at first.
Exposure limits
OSHA’s limit is a ceiling of 1 part per million, never to be exceeded. NIOSH considers 10 ppm immediately dangerous to life or health. See Exposure Limits.
Working around chlorine systems
- Get trained on your site’s chlorine procedures, alarms and evacuation routes.
- Use fixed chlorine detectors and portable monitors where gas can be released. See Gas Detectors.
- Secure cylinders, keep valve caps on when not connected, and use the right connections and gaskets.
- Only trained responders with the right respirators and emergency kits should stop leaks. See HAZWOPER.
- Keep an escape respirator where your site requires one.
If chlorine is released
- Leave the area and go uphill and upwind, away from low spots.
- Warn others and call 911 or your site emergency number.
- If you were exposed, remove contaminated clothing and wash skin with lots of water.
- Flush eyes with water for at least 15 minutes. See Eyewash & Showers.
- Get medical care, and tell the provider it was chlorine.
Daily checklist near chlorine systems
- Detectors working and no alarms
- Cylinders secured and labeled
- Escape respirator and wind sock or wind direction known
- Eyewash tested
- Cleaners stored apart, never mixed
Standards & references
Last updated: