One pool chlorine product + A different pool chlorine product
Heat, fire, or chlorine gas
Never mix different pool chemicals, including different types of chlorine products, with each other or with anything else. [1]
If you already mixed
Leave the area right away and get to fresh air. For household cleaners, open windows and doors to let in fresh air, and stay away until the gas has gone away. [2] [3]
Call 911 for any trouble breathing or swallowing. [2]
Eyes: rinse with lots of room-temperature running water for at least 15 to 20 minutes. [4]
Remove contaminated clothing; wash skin with soap and water. [5] [6] [2]
For mild symptoms or questions, call Poison Help 1-800-222-1222. [2]
A fading smell is not an all-clear: the smell may not be noticeable to people exposed many times, and chlorine gas is heavier than air, so it may linger near the ground. [6]
EPA says the most common pool chemicals are inherently incompatible with each other; mixing can make enough heat to ignite nearby combustibles and can release toxic chlorine gas. [7]
EPA also warns not to mix old and new chemical even of the same type. [7]
Chemicals
Sources
- CDC — Use Pool Chemicals Safely (poster) retrieved 2026-10-27
- Washington Poison Center — Chloramine Gas retrieved 2026-10-27
- Centers for Disease Control and Prevention — Chlorine fact sheet retrieved 2026-10-27
- National Capital Poison Center (Poison Control) — Help for poisons splashed in the eye retrieved 2026-10-27
- NJ Department of Health — Hazardous Substance Fact Sheet: Sodium Hypochlorite retrieved 2026-10-27
- National Capital Poison Center (Poison Control) — Chlorine gas retrieved 2026-10-27
- U.S. EPA — Chemical Safety Alert: Safe Storage and Handling of Swimming Pool Chemicals (2001) retrieved 2026-10-27