Ask about the energy-consumption of gadgets when you buy them. All these options are useful but a catalytic converter will cut out 90 per cent of emissions of carbon monoxide, nitrogen dioxide and hydrocarbons. However, a catalytic converter does not tackle carbon-dioxide emissions, which contribute to the greenhouse effect. By far the best course is to use your car less. By the age of 12 years old a child will have eaten about half a pound weight of coal-tar in the form of food colouring and dye.
Some colourings cause allergies and hyperactivity, while the effects of many others are unknown.
Taking too much vitamin C is unlikely to be harmful. And the manufacture of aerosols consumes considerable resources. Refillable pump-action containers are preferable. But vast tracts of tropical forest are destroyed to create grazing for cattle, Usually owned by rich ranchers who already have too much land. Tropical forests are also destroyed to make way for the hydroelectric plants to smelt bauxite - used in aluminum cans.