Ozone comes in basically two forms – the good and the bad. Good ozone is the ozone formed in the stratosphere that forms a protective layer to block out harmful ultraviolet radiation from reaching the Earth’s surface. We have all heard of the ozone hole created primarily by excess chlorofluorocarbons, or CFC’s, that deplete the stratospheric ozone and let the harmful ultraviolet rays reach the Earth’s surface. But ozone has another face, the bad ozone, that is present in our atmosphere in the air we breathe.
This ozone is formed from the reaction of oxides of nitrogen with volatile organic compounds, or VOC’s, in the presence of sunlight. The optimum conditions for the formation of ground-level, bad ozone occur when the air temperatures are in the 80’s and 90’s and the winds are calm.
Ozone is one gas that is known to make respiratory problems, such as asthma or chronic obstructive pulmonary disease (COPD), worse and exposure to ozone tends to affect young children and senior citizens the most. The Environmental Protection Agency (EPA) monitors ozone levels and it is one gas used to calculate the Air Quality Index, or AQI. When atmospheric ozone is at a concentration of 54 ppb (parts per billion) or lower, the AQI is 50 or less and the air quality is said to be good. But as the ozone concentration increases to values greater than 70 ppb, its effects begin to be felt by some persons who may have existing health problems such as asthma or COPD. At much higher levels, ozone action days may be proclaimed which means that the outdoor ozone concentrations are high enough to affect many more people and people are generally told to stay indoors to avoid health problems. A short synopsis of ozone can be found on the website below that is maintained by the EPA.
https://www3.epa.gov/airnow/ozone-c.pdf
Considerable more detail about the health problems associated with ozone can be found on the following website dedicated to ozone awareness.
http://ozoneaware.org/
We all know that if ozone is present in the atmosphere outside our homes and offices, then some of this ozone may make its way indoors adding to indoor air pollution. But in an attempt to clean the indoor air of gaseous pollutants, many people turn to ozone generators that are said to remove contaminants and pollutants from the indoor air. The bottom line is that these ozone air cleaners create ozone and that the ozone created may make your indoor air more hazardous to breathe. The problem is potentially severe, so much so that the EPA has dedicated a website about the hazards of ozone air cleaners. It can be found at the link below and is well worth the read since it also contains some basics about reducing indoor air pollution for a healthier lifestyle.
https://www.epa.gov/indoor-air- quality-iaq/ozone- generators-are- sold-air- cleaners
Dave
Senior Scientist, Airviz Inc.
