Air pollutants: heavy metals overview

Heavy metals (HMs) occur naturally in the environment, but with variations in concentration. They are also released to the environment from a range of human and natural sources. Heavy metals are usually carried on fine particles.

Some heavy metals, along with Persistent Organic Pollutants (POPs), form part of the class of air pollutants referred to as Hazardous Air Pollutants (HAPs).

The environmental and human health effects of heavy metals depend on the mobility of each metal through environmental compartments and the pathways by which metals reach humans and the environment. The degree of concern about human and environmental health varies with each metal. Some metals are toxic. Others are known to be essential micronutrients for humans and animals.

Respiration and ingestion with food are two pathways for many metals entering humans.

Due to atmospheric transport and other pathways, the Arctic region, including the Canadian Arctic, is a major receptor of some heavy metals such as mercury, cadmium and lead released from sources in other regions of the world.