A pool operator at a small community pool in California mixes two common pool chemicals and accidentally creates a poisonous gas cloud that emanates from the pump room out onto the pool deck and makes 50 people sick, including kids in swim lessons and other patrons.
See the story and news video here from Mercury News:
https://www.mercurynews.com/2018/06/14/potentially-deadly-chemical-mix-gasses-20-at-san-jose-pool/
Safety Tips:
1. Always add chemicals to water. NEVER add water to chemicals.
2. Don't mix chemicals before adding to the pool.
3. Be sure your bucket/scoop is clean and does not contain chemical residue before adding a new chemical to a bucket.
4. Rinse buckets with water after use.
5. Do not walk away from chemical-soaked cotton rags without rinsing them out first.
6. ALWAYS wear your PPE (personal protective equipment) when handling chemicals.
7. Always clean up chemical spills immediately.
8. Store pool chemicals in dry weather-protected areas outside of sunlight.
9. Read the instructions on chemical containers! It seems silly, but we do it all the time even though we have worked with the same chemicals for many years.
10. Always have your SDS (MSDS) sheets on hand at your facility and ready to go if you should have an accident. Keep them in a "Right to Know" binder on the wall and if an exposure accident should occur, rip the chemical SDS sheet out and send it with the exposed person to the hospital.