Common Sources

Most people recognize ozone from its presence in the ozonosphere, or ozone layer, where it functions to protect the Earth from harmful ultraviolet rays. Ozone is a naturally occurring gas, and exists only in small quantities outside of the ozonosphere. Ozone is most commonly formed during electrical storms, where an electrical spark will cause the creation of a three-atom molecule. This ozone actually poses no human threat, as the gas’s existence is only dangerous if the concentration gathers at ground level. Ozone on a ground level occurs when sunlight reacts with volatile organic compounds, which exist in sources such as hydrocarbon vehicle emissions. Electrical sparks which create ozone may occur inside the home in any equipment which uses high voltage or ultraviolet light. These items include electric motors, high power office equipment (photocopiers or laser printers), or electronic air filters which have been improperly installed.

Ozone control is complex because, though both indoor and outdoor processes can create the gas, studies have shown that the outdoor level is responsible for the inside level. A low indoor level of ozone reflects a low outdoor level, and a high indoor level reflects a high outdoor level. However, indoor concentrations should still be monitored since they can affect home occupants adversely, and the gas can have more serious effects if a buildup occurs.

Health Effects

Even at relatively low concentrations, ozone can trigger several symptom, including irritation of the eyes, respiratory tract, nose, throat, and trachea. Signs of irritation include heavy coughing and tightness in the chest area. If the gas reaches a higher concentration, it may hamper lung function seriously. If exposure is long-term, an increase in bacterial infections may occur, as well as possible thickening of lung tissue or changes in the central nervous system. Those most at-risk are persons who work or exercise outdoors where a high concentration of ozone is present, such as large cities with a high smog content.

Exposure Guidelines

For acceptable short-term exposure range, an ozone concentration of less than or equal to 0.12 ppm (parts per million) on a one-hour average concentration is recommended. Ozone is a pollutant which is relatively new to studies, and therefore not enough research has been done to produce acceptable levels over a long-term period.

Prevention

Ozone is a difficult problem to control, since outdoor levels are highly responsible for indoor levels of the gas. Higher indoor levels are much more commonplace in larger cities with a high pollution or smog content. This heavy air pollution is associated with a high ground level ozone content. Homeowners can, however, control the ozone problem to some degree. Anyone should be cautious when purchasing any home equipment which uses ozone to purify air or water. Any high voltage office equipment or electronic air filter should also be seen as a potential problem area. Any and all of the aforementioned equipment should also be regularly checked out and maintained.

As with most other indoor air pollutants, a balanced mechanical ventilation system can help by removing indoor air and replacing it with fresh outdoor air. However, in some areas this may not be a solution for ozone pollution since outdoor levels are higher than indoor levels, especially in larger cities. If this is the case, filters can be installed into the ventilation system to combat any ozone influx. The most effective filters are those who make use of activated carbon compounds to chemically alter ozone back into oxygen, making it safe to breathe.