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Air Quality FAQs


Here are a few of the most asked questions about Air Quality in London:

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  • What is Smog?

    In Ontario, “smog” usually refers to ground-level ozone, which is created when nitrogen oxides (from tailpipes and power plants) and volatile organic compounds  (from oil-based paints, gasoline fumes) are “cooked” by sunlight over a couple of hours.

    Sometimes it also refers to fine particulate matter, a mixture of very small particles and acid aerosols created by sulphur dioxide and nitrogen oxides, which most people see as “haze” on an otherwise sunny day.

  • Does the City of London have an Idling By-Law?

    Yes, under the Idling Control By-law (PH-15), vehicles are not allowed to idle for more than two minutes.  There are exemptions, such as when the outside temperature is more than 27°C or less than 5°C, defrosting or defogging a windshield prior to driving, or if a vehicle needs its engine running to operate on-board work-related equipment (e.g., a refrigeration truck, crane, etc.).

  • How is the Idling By-Law enforced?

    The by-law is enforced a couple of times per year through “blitzes” at locations throughout London a couple of times during the year.  These are primarily for public education purposes, and by-law enforcement officers have rarely seen anyone exceed the by-law limit during these “blitzes”.

  • My neighbours are always idling their vehicle – can you issue them a ticket?

    No, the City of London does not the staff resources to respond to complaints at specific locations. However, we can send a letter to the owner of the vehicle to let them know that a complaint has been received.

  • Smoke from neighbour’s fire pit is bothering me – can you issue them a ticket?

    Contact the London Fire Department about complaints or other concerns about someone’s backyard fire pit. See the Fire Department’s Open Air Burning By-law for more information.