Ozone: Friend or Foe?

The topic of ozone is generally discussed in an environmental discussion regarding pollutants in the air. It’s a term you may here often, but it’s not a term everyone fully understands. You hear statements about the ozone layer depleting and how we need to prevent the hole from getting bigger, but a couple seconds later somebody else would mention ozone being a pollutant. If you’re not in the field of Environmental Science or have much background in this area the topic of ozone can get confusing. With ozone being such a prevalent pollutant in our system, it should be a topic everybody is educated on to understand the extent of the problem.


Ozone is a molecule that consists of three oxygen atoms bonded together. It can be found in two regions of the Earth - the upper portion of the atmosphere, approximately 3 times higher than where an airplane flies, and at ground level.


The layer of ozone found in the upper atmosphere is the Ozone Layer and is considered the “good ozone”. It is a layer of protection that prevents most of the Sun’s harmful ultraviolet rays from penetrating the Earth. Unfortunately, the presence of nitrogen oxides from jet engines in this part of the atmosphere causes the concentration of ozone to decrease and therefore resulted in the depletion of the ozone layer. This depletion is causing harmful ultraviolet rays to enter the Earth’s atmosphere and increase the chances of various health problems like genetic damage, and skin cancer.


Ground-level ozone is considered the “bad ozone”.  It is created through a chemical process between nitrogen oxides (NOx) and volatile organic compounds (VOCs), which are generally produced from industrial factories and vehicle exhaust. The growing urban population is a major reason for the increase of pollutant levels, which in turn increases the level of ozone. These high concentrations are causing adverse health effects like lung disease, chest pain, throat irritation, cardiovascular disease, and increase asthma symptoms.


According to studies conducted by the Toronto Public Health Department and the Ontario Medical Association, air pollution has increased the number of hospital admissions and emergency room visits. As seen from the picture below, it was found that approximately 5% of cardiopulmonary mortalities have been related to ozone exposure. By reducing the ground-level ozone and other pollutants by 10% across Canada it would reduce hospital admissions and emergency room visits by thousands.


Although this is a global issue, there are multiple actions individuals can take to decrease the amount of pollutant they produce. Some contributions we can make individually are to conserve energy by turning off electronics when not in use, choosing a “green” form of transportation like walking, biking, or electric cars, and making educated decision when choosing products for purchase. You can be the start of the change we need to see.

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