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occupational health branch

May 2023 Occupational Health Watch

May is Asthma Awareness Month: Dangers of Mixing Chemicals 

Cleaning “hacks" and DIY recipes proliferating on social media may be leading people to get creative to try to save money, be healthier, or get better cleaning results. This is a reminder that mixing chemicals together can be dangerous. This is true even of vinegar, ammonia, or other common products. For example, vinegar or other acids when mixed with bleach create chlorine gas. Ammonia when mixed with bleach will release chloramine gas. These are just two of many reactions that can cause asthma, eye and lung irritation, or even death.Cleaner with materials

In California, the Work-Related Asthma Prevention Program has tracked over 50 cases of asthma caused by or made worse when cleaning products were mixed improperly at work. Additionally, the Occupational Pesticide Illness Prevention Program has tracked nearly 250 cases of other illnesses and injuries caused by mixing disinfectants with other products at work. Altogether, the health effects from mixing products included new onset asthma, asthma exacerbation, chest pain and tightness, cough, shortness of breath, and eye irritation.

Workers should be trained or reminded not to mix products together unless the product label explicitly includes instructions to do so. 

Additional safety tips:

  • Use as much ventilation as possible. Open windows if needed.
  • Dilute products properly. Do not make them more concentrated than the labels say.
  • Follow directions on the label or the safety data sheet. This may include wearing gloves and/or goggles.
  • Choose fragrance-free cleaning products.​​

Case study:

A 52-year-old hotel worker was cleaning a grimy toilet. Her supervisor asked her to add a lot of an acid toilet cleaner, and then to put in an abrasive cleanser as well. The mixture began to bubble and give off vapors. Soon, her eyes were red, and she felt like she was choking and short of breath. She developed asthma from the incident that has never gone away.


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