Plastic bags come in two basic types: thick bags used for clothes, CD’s, electrical appliances and other goods, and thin bags used by supermarkets and take-away food stores.

Thick plastic bags are made of low density polyethylene (LDPE). These are generally used for higher value items such as clothes.

Thin bags are made of high density polyethylene (HDPE). Both types of bags are made from the by-products of fossil fuel production, so they come from non-renewable resources.

Polyethylene is made from long-chain hydrocarbon (hydrogen and carbon) molecules called polymers.

Polymers are large, tightly bound molecules that bacteria and other microbes find difficult to break down. Because the molecules are difficult to beak down, plastic bags stick around in the environment for up to 1000 years.

The story of plastic bags begins with the mining of fossil fuels such as oil, coal and gas. The by-product of fossil fuel production is ethylene. One molecule of ethylene has two carbons and four atoms of hydrogen.

Ethylene is then turned into polyethylene, a long chain of ethylene molecules tightly joined together. The polyethylene is made into plastic pellets, which are then used to make plastic bags.