Hazardous waste is anything that can cause ecological problems if it is either put down the drain or sent to a regular landfill site. The five primary categories are:
EXPLOSIVE -- the most common household product in this category are aerosol cans that if heated or crushed could explode and cause harm with flying metal parts.
CORROSIVE -- many cleaning products can be corrosive, potentially burning skin of anyone associated with a land fill or garbage collection or pollution of the water table below the land fills.
FLAMMABLE -- simply means it can catch of fire. If poured down the drain these products could actually catch on fire as they float in the sewer lines, kill water treatment chemicals and enzymes, and generally pollute the waterways.
POISON -- includes prescription medicines. Now you can take old expired medicine to the drug store where they will properly dispose of it.
POLLUTING -- Old batteries and old smoke alarms have dangerous chemicals in them. You can return these to the renovation centres and they will take care of them.
Many products will fall into more than one category so you should look for the warning symbols.
Check with your local municipality for annual or sem-annual hazardous waste drop off programs where they will take all your nasty stuff.