Toxic substances list: ozone

Ground-level ozone is a colourless gas found in the lower atmosphere. Virtually none of the ground-level ozone measured in air is directly emitted from biogenic (natural) or anthropogenic (human) sources. Ozone is the product of a complex series of chemical reactions primarily involving sunlight and two precursor pollutants: nitrogen oxides (NOx) and volatile organic compounds (VOCs). These precursor gases are emitted from combustion processes often associated with industry and the transportation sector, and from various commercial and industrial processes and solvent use. Some NOx and VOCs may be produced by biogenic sources, especially in summer when VOC emissions from vegetation (agricultural crops and forests) are greatest. Ozone and the precursor gases can be transported over long distances. This phenomenon is often found in the north-eastern United States and in eastern Canada where large weather patterns are not impeded by major geographical features.

CAS (Chemical Abstract Service) registry number: 10028-15-6

Risk Assessment


This substance is entering the environment from the following source(s):

Risk Management Strategy

Click on the following link to view strategies and actions recommended to manage risks associated with the substance:


Substances Management Information Line
Chemicals Management Plan
Gatineau, QC K1A 0H3

Telephone: 1-800-567-1999  (in Canada) or 819-938-3232
Fax: 819-938-3231


Return to Substance List

Page details

Date modified: