In Ontario and other Canadian smog 'hot' spots, summer means smog, just as sure as it means swimsuits and no school. The early May smog advisory means this summer will be no different.

Smog advisories mean much more than just hot weather or ugly skylines - they hold serious threat for children, the elderly, people with asthma, those with heart problems or anyone who works or exercises outside. Hospital visits for breathing problems skyrocket during smog events and premature deaths have occurred during the most extreme events.

The frequency of smog advisories can cause us to see it as a natural part of summer — or at least too big for us to do anything about. But, each of us can limit our contributions to smog, even those of us who don't live in smog centres like Toronto.

But first — What is smog?

The word smog is actually a combination of two words — smoke and fog. These two descriptions are quite fitting since smog can be thick and low-hanging — like fog, but also cause breathing difficulties — like smoke. Smog is caused by the emissions we release through our various everyday activities — the largest contributor being the burning of fossil fuels in our cars and electricity plants.

Did you know? You release VOCs into the atmosphere by using various consumer products such as hair spray, antiperspirants, cleaning products and pesticides, and through your everyday activities like driving and controlling the temperature at your house.

Fossil fuels are long strands of hydrocarbons (chains of hydrogen and carbon molecules). When they are burned inefficiently, smaller hydrocarbons are produced which are quite reactive and evaporate quickly. These reactive and small hydrocarbons are called volatile organic compounds(VOCs) react with nitrogen oxides, or NOx (by-products of inefficient fuel combustion), and sunlight to form ground-level ozone (O3) — the 'smoky' part of smog that makes breathing so difficult.

VOC + NOx + sunlight --> O3

Ground-level ozone has the same chemical composition as atmospheric ozone but their location dictates very different roles. Atmospheric ozone protects us from UV rays while ground-level ozone harms our lungs.

The majority of VOCs in the earth's atmosphere are actually produced naturally from the decomposition of trees and forest fires. However, natural VOCs occur mainly in the countryside where NOx is limited. VOCs produced by human activity (i.e. vehicles) are a problem since they are concentrated in urban centres where there are also high concentrations of NOx.

Did you know? While heat can speed up the formation of ozone, it is not required. This means that any sunny day with an excess VOC, NOx and PM can produce a smog episode — even in February!

The 'foggy' part of smog comes from fine particulate matter which gets suspended in the air during hot, calm weather and provides pockets for more VOC/NOx reactions to take place. Particulate matter, or PM, can have natural sources, but also can be generated as water vapour or sulphuric emissions from vehicles or other fossil fuel burning activities.

O3 + PM --> SMOG

Protect yourself from smog!

Here are some easy ways to stay clear of smog:

Check the TV, radio, newspaper or internet for smog advisories Stay inside during smog episodes Those who work outdoors during the summer may welcome the odd smog event as it means a day off. But with increasing frequency of episodes over the summer, smog days may end up costing you — and your employer loads of cash in lost work hours.

Smog can compromise days at the beach, summer hiking or canoeing, even walks or bike rides through the city. Do your part to stop smog from ruining your summer! Use public transit or carpool (tell family and friends to do the same) Ask friends and family to not idle vehicles Plant trees for shade around your house — it will lower your A/C use BBQ and have campfires in the evening — not during peak summer hours Get your parents to turn your lawn into a garden — less grass cutting for you, and fewer emissions for the air! Find out more about VOCs and try to curb your use of them.

Learn More!

Primer on Automobile Fuel Efficiency and Emissions (Pollution Probe) Primer on Volatile Organic Compounds (Pollution Probe) Air Quality Ontario (Ontario Ministry of the Environment and Climate Change) Check out your daily air quality, and sign up for advisories!

Rebecca Spring

I am a science communication graduate. I work at an environmental organization in Toronto. In my free time, I am learning Spanish so I can travel and work in South America.

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