Never mix commercial cleaning products; some have dangerous reactions.
One notorious example of this is when ammonia-containing products are mixed with chlorine bleach: the resultant reaction forms toxic chloramine gases that are respiratory system irritants. Symptoms of exposure include eye, nose and throat irritation, coughing, wheezing, chest pain and nausea.
Ammonia is present in many households; common sources are cleaners and fertlisers.
The active ingredient in chlorine bleach is sodium hypochlorite, and is found in many disinfectants. Apart from with ammonia, sodium hypochorite may react with drain cleaners (never use two drain cleaners together) and other acids. Bleach mixed with acids produces chlorine gas, which is also a respiratory irritant.
Pool chemicals may also contain sodium hypochlorite or other reactive ingredients, and shouldn't be mixed with household cleaners.
In addition to not mixing products, these straightforward tips will help keep you and your family safe:
Read product labels and take heed of contents, manufacturer instructions and safety warnings.
Ensure good ventilation (i.e. at least an open window) while you’re working with chemicals, use gloves, and wash your hands well afterwards
If you notice any symptoms (e.g. eye, nose or throat irritation, headache, nausea, skin irritation) while working with chemicals, leave the area at once and get outside into the fresh air.
Store home-cleaning, gardening and pool supplies well beyond the reach of children.
Keep the number of toxic chemical products in your home to a minumum, and use non-toxic alternatives whenever possible. The individual amounts and concentrations may be low and (hopefully) not harmful, but they all add up. They aren't good for us, nor for the wider environment when they get washed down the drain.
- Olivia Rose-Innes, EnviroHealth Editor, Health24, July 2012