Explosive risk of aerosols

IN ORDER to make sure products such as air fresheners of spray paints are spread evenly when released, they need to be pressurised.

But the products themselves do not compress easily, so they need to be mixed with gases whose molecules do.

This used to be done with chlorofluorocarbons (CFCs) until 1980, when they were replaced because of damage to the ozone layer.

The gases that replaced CFCs, such as propane and butane, are flammable. Once released from the container they spread quickly, risking an explosion if ignited in a confined space.