Ozone is an unstable gas found in both the upper and lower parts of the earth’s atmosphere. We often hear about the depletion of the ozone layer, which refers to the upper part of the earth’s atmosphere and is “good” ozone that we need to preserve. In contrast, the ozone in the lower part of the atmosphere is “bad” ozone that pollutes the air.

Good Ozone Versus Bad Ozone

Good ozone in the earth’s upper atmosphere (stratosphere) protects us by acting as a barrier to harmful UV rays. Bad ozone is formed in the lower atmosphere (troposphere) when sunlight reacts with certain chemicals. Motor vehicles, industrial processes, household solvents and appliances emit toxic chemicals into the lower atmosphere, and many of these are volatile organic compounds (or VOCs). The earth’s tropospheric ozone is the primary component of smog.

Effects of Ozone on Human Health

Because reactions involving sunlight produce ozone, the effects are worse on sunny days than on cloudy days.  Initial exposure causes irritation of the eyes and lungs, while prolonged exposure can result in serious respiratory illnesses or increased severity of preexisting conditions like asthma. It is best not to exercise outdoors while ozone levels are high, particularly in the summer months.

Effects of Ozone on Vegetation and Climate

Tropospheric ozone (the bad ozone) is the third most dangerous greenhouse gas after carbon dioxide and methane. This ozone blocks radiation from leaving the earth’s atmosphere, traps heat inside, and contributes significantly to global warming.

High ozone concentrations can also interfere with photosynthesis of plants and stunt their ability to turn sunlight into food. This slows their growth and makes them more vulnerable to disease and harsh weather. As a result, ozone is a key factor in reduced crop yields and damaged vegetation, and is thought to be a primary cause in the decline of certain tree species like Southern California pines, which are a valuable source of oxygen.

What Can We Do to Reduce Ozone Emissions?

Keep your family and pets safe by becoming aware of the products and appliances in your home that contribute to bad ozone. Read labels to ensure you are using low-VOC-content paints, solvents and carpets (or choose alternate flooring).  Avoid pressed wood and plywood in home projects, and use natural cleaning products and natural body products (soaps, lotions, shampoos) with ingredients you recognize rather than chemically-produced or chemically-scented products that often contain VOCs. Avoid nail polish and remover with acetone, buy clothes that don’t need to be chemically dry cleaned, and buy naturally-dyed or undyed goods rather than chemically-dyed products.

Keep printers, copiers and other electronics and appliances off when not in use, as they tend to heat up and emit VOCs. If you normally drive, you can minimize your contribution to ozone-creating vehicle emissions by choosing to walk, bike, or take public transportation at least one day a week. If driving to work is a must, you can organize a carpool and make sure you maintain  your vehicle.