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The heat, the sunshine…it’s ozone season in Spokane.

Summer is in full swing and so is the heat. Temperatures have now settled into the seasonal upper 80s and 90s. As the temperature heats up, ground-level ozone pollution tends to increase as well. So what exactly is ozone?

Good up high, bad nearby

Ozone can be found in two locations – in the Earth’s upper atmosphere where it protects us from UV radiation and at ground-level on the Earth’s surface. When ozone is found at ground-level it is a harmful air pollutant that is a key component in smog. Exposure to elevated ground-level ozone pollution can cause respiratory problems and aggravates asthma in children.

Healthy adults can experience a 15-20% reduction in lung function from prolonged exposure to low levels of ground-level ozone pollution.

Nothing emits ozone directly to the air, it is formed photochemically

Ground-level ozone pollution is formed by photo-chemical reactions between oxides of nitrogen and volatile organic compounds (VOCs) in the presence of sunlight and heat. Because of how it forms, ozone pollution is only a concern during the hot, summer months – typically late June through August in Spokane.

VOCs are emitted to the air from a variety of activities, including:

  • Industrial and commercial operations
  • Vehicle refueling, driving
  • Using lawnmowers and other gas-powered equipment
  • Using products such as cleaners, paints/solvents, BBQ lighter fluid, etc.
Ozone trends chart

Above: The 3-year average trend chart for ground-level ozone pollution. As you can see, Spokane’s ground-level ozone pollution concentrations come very near to the health-based standard that is set by the EPA. With the pandemic, ozone levels tampered off a bit. Perhaps it is because fewer people were driving to work. The next three-year average (2020-2022) chart may be more revealing.

The good news is we can all make choices to prevent ground-level ozone pollution, such as:

  • Reduce car trips by combining errands. Walk, bicycle or ride the bus once a week, instead of driving alone.
  • Refuel in the evening. This keeps ozone-forming vapors out of the air during the heat of the day.
  • Hold off using gas-powered lawn equipment until evening.
  • Use manual or electric yard and garden tools.
  • If you use a charcoal barbecue, start it with an electric probe instead of lighter fluid.

During the summer, it’s important to monitor the Air Quality Index and take health-based precautions. When ground-level ozone pollution reaches unhealthy levels, limit strenuous outdoor activity. If you exercise outdoors, do so early when ozone pollution is lower. Also, pay attention to respiratory symptoms such as coughing, wheezing, discomfort. See your health care provider if necessary.

Here is a 53-second video about ozone pollution.

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