Never mix Sodium hypochlorite (chlorine bleach) with Acetic acid (vinegar)
Toxic gas
Chlorine gas is released. It is an immediately dangerous respiratory irritant with a sharp distinctive smell. Even low levels for short periods irritate the eyes, nose and throat and cause coughing and breathing problems; higher levels cause chest pain, severe breathing difficulty, vomiting and lung damage, and very high levels can be fatal. Leave the area for fresh air at once and seek medical advice. FEELING BETTER SHORTLY AFTERWARDS IS NOT AN ALL-CLEAR: the regulator recommends medical observation for 24 to 48 hours, because fluid on the lungs can be delayed.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Rinse thoroughly afterwards
- Keep away from children and pets
- Consider professional help
How this happens
Acidifying a hypochlorite solution liberates chlorine gas. Any acid does this, which is why the rule cannot usefully be a list of products: descalers, limescale removers, toilet cleaners, some dishwasher and drain products and vinegar are all acidic, and several are sold for the same surfaces as bleach. The most common route is SEQUENTIAL rather than simultaneous — one product used, inadequately rinsed away, and a second applied to the same surface or drain shortly after. Both cases in the New Jersey hazard alert happened that way, one in a dishwasher and one in a drain.
If it has already happened
Get everyone into fresh air straight away, and do not go back inside to open windows. Anyone with breathing difficulty, chest pain, persistent coughing, or a chemical splash to the eyes needs medical attention — treat it as an emergency and call your local emergency number. In the United Kingdom, use NHS 111 or 999 as appropriate; clinicians can consult the National Poisons Information Service.
The substances involved
- Sodium hypochlorite (chlorine bleach) — A powerful oxidising bleach and disinfectant. It is also the substance behind the most common serious household chemical accidents, and must never be mixed with anything.
- Acetic acid (vinegar) — The acid in vinegar. Genuinely effective on limescale and mineral films, and routinely recommended for surfaces it should never touch.
Evidence
Strongly supported
Sources
Hazard Alert — Worker Health and Safety: Mixing Bleach with Other Cleaning Products Can Be Deadly
New Jersey Department of Health, Environmental and Occupational Health Surveillance Program · Government or regulator
Relied on for: That mixing chlorine bleach with an acid produces chlorine gas with the effects described, and two case reports in which the exposure arose sequentially rather than by deliberate mixing. (states this directly)
Dangers of Mixing Bleach with Cleaners
Washington State Department of Health · Government or regulator
Relied on for: That mixing bleach with acids gives off chlorine gas, that it irritates the mucous membranes and causes coughing and breathing problems, and that very high levels can cause death. (states this directly)
Right to Know Hazardous Substance Fact Sheet: Chlorine
New Jersey Department of Health · Government or regulator
Relied on for: That medical observation is recommended for 24 to 48 hours after breathing overexposure to chlorine, as pulmonary edema may be delayed. (states this directly)
Right to Know Hazardous Substance Fact Sheet: Sodium Hypochlorite
New Jersey Department of Health · Government or regulator
Relied on for: That sodium hypochlorite may react violently or explosively with strong acids, acid compounds and acid-based cleaning compounds such as brick and concrete cleaners, to release chlorine and other toxic gases. (states this directly)