What is smog?

Smog is a noxious mixture of airborne pollutants. The main components of smog are ground-level ozone and fine particles known as particulate matter. Pollution from industrial sources and vehicle exhausts are the primary contributors to smog. Smog most often appears as a brownish-yellow haze on hot, sunny, summer days.

How does smog affect me?

Data released in 2008 by the Ontario Medical Association (OMA) shows that air pollution is a contributing factor in almost 9,500 premature deaths per year in Ontario.
How air pollution affects your health is determined by the length of time you are exposed, your health status and your genetic makeup, and the concentration of pollutants. Air pollution can have a negative effect on your respiratory system (lungs and airways) and on your cardiovascular system (heart function and blood circulation) by;

  • make it harder to breathe,
  • irritating your respiratory system,
  • triggering episodes of asthma and Chronic Obstructive Pulmonary Disease (COPD); chronic bronchitis and emphysema, 
  • triggering episodes of heart conditions (angina, heart attack, heart failure and heart rhythm problems).

What is ground-level ozone?

Ground-level ozone is produced by a reaction in the lower atmosphere between nitrogen oxides (NOx) and volatile organic compounds (VOC). Nitrogen oxides are produced when fossil fuels are burned such as gasoline, natural gas, heating oil and coal. Volatile organic compounds originate mainly from the evaporation of liquid fuels, solvents and organic chemicals and from burning of gasoline.

What is Particulate Matter?

Airborne particulate matter (PM) is the general term used to describe a mixture of tiny solid particles and liquid droplets found in the air we breathe.  The health affects associated with PM depends greatly on particle size.
The greatest health hazard from particles comes from the smallest ones – 2.5 microns (2.5 µm) in diameter or less – because we easily inhale these small particles into our lungs.  These are called Fine Particulate Matter 2.5 or PM2.5. Particulate Matter 10 or PM10 refers to particles with a diameter less than 10 microns (10 µm).  To put things in perspective, a fine particle is approximately 30 times smaller that the average diameter of a human hair.

What causes smog to form?

Smog-forming reactions occur near ground level and are dependent upon high temperature, sunlight and the presence of pollution originating from various sources including:

Vehicle Exhaust
Vehicle Exhaust
Factories & Utilities
Factories & Utilities
(e.g. Oil-Based Paints,
chemical sprays and cleaners)
Lawnmowers and other gasoline or diesel powered machinery
Lawnmowers and other
gasoline or diesel powered
Asphalt road paving and construction
Asphalt road paving
and construction