Non-Criteria Air Contaminants

Non-criteria pollutants are the entire range of contaminants other than the CACs, including other toxic and hazardous pollutants. Although most of them have not been studied, those with significant information related to their health effects include: lead, benzene, dioxins, furans, polychlorinated biphenyls (PCBs), pesticides, ammonia, hydrogen sulphide, pollen, and spores.


Diesel exhaust, wood smoke, and industrial emissions contain many toxic chemicals including formaldehyde, chromium, benzene, 1.3 butadiene, and acrolein.

Under the Canadian Environmental Protection Act, 1999 (CEPA 1999) a substance is considered toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that:
1. have or may have an immediate or long-term harmful effect on the environment or its biological diversity;
2. constitute or may constitute a danger to the environment on which life depends; or,
3. constitute or may constitute a danger in Canada to human life or health.

CEPA Toxic Substances List

Air toxics are associated with a broad range of health effects including cancer and damage to the lungs, brain, nerves, immune system, and reproductive system. A number of them can be grouped according to common properties including, for example, their composition, reactivity, and health effects. Persistent organic pollutants and heavy metals are two very important toxic sub-categories.


Persistent organic pollutants can last in the environment for long periods of time and are capable of travelling great distances in the air. They can also 'travel' up the food chain, bioaccumulating in body tissues. Even in low concentrations they can cause cancer and are disruptive to many critical biological functions including endocrine, reproductive, immune, and neurological.

POPs are used in industrial processes, in pesticides, and in the production of goods such as solvents, polyvinyl chloride, and pharmaceuticals. A list of the most studied POPs, known as the dirty dozen, includes: aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and toxaphene. There are many other POPs of concern, including carcinogenic polycyclic aromatic hydrocarbons (PAHs), brominated flame-retardants, and organometallic compounds like tributyltin.

Dioxins are one of the most poisonous chemicals known.

For more information click here:DIOXINS


Heavy metals, such as mercury and lead can become airborne and eventually enter water and food supplies. Like POPs, they can bioaccumualate in body tissues, are poisonous in low concentrations, and can cause a wide range of biological system failures. Heavy metals contaminants can become localized in mud and soil and, if left undisturbed, lay dormant indefinitely.

Some metals such as iron, cobalt, copper, manganese, molybdenum, and zinc are required by humans in minute amounts but are damaging in excessive amounts. Some are carcinogenic or toxic to the central nervous system (manganese, mercury, lead, and arsenic). Some affect the liver and kidneys (mercury, lead, cadmium, and copper). And some affect the skin, bones, or teeth (nickel, cadmium, copper, chromium).


Hazardous air pollutants are contaminants other than the CACs for which there are specific health concerns based on clinical or animal studies. Measurements for airborne HAPs are much less common than for CACs.

As defined by the US Environmental Protection Agency, HAPs are derived from chemicals used or produced in industrial processes. Examples include benzene, which is found in gasoline; perchloroethylene, which is emitted from some dry cleaning facilities, and methylene chloride, which is used as a solvent and paint stripper.

The list of hazardous pollutants includes toxins from the POPs and heavy metal categories. HAPs include methanol, manganese compounds, hydrogen sulphide, hydrochloric acid, chlorine, chlorine dioxide, phenol, methyl ethyl ketone, catchecol, cumene, o-cresol, styrene, 1,2,4-trichlorobenzene, o-xylene, and beryllium.