Ozone Testing

epa_cover_pic.jpgHow Can Ozone Be Both Good and Bad?

Ozone occurs in two layers of the atmosphere. The layer closest to the Earth’s surface is the troposphere. Here, ground-level or “bad” ozone is an air pollutant that is harmful to breathe and it damages crops, trees and other vegetation. It is a main ingredient of urban smog. The troposphere generally extends to a level about 6 miles up, where it meets the second layer, the stratosphere. The stratosphere extends upward from about 6 to 30 miles. The stratospheric or “good” ozone protects life on Earth from the sun’s harmful ultraviolet (UV) rays.

What is Happening to the “Good” Ozone Layer?

Ozone is produced naturally in the stratosphere. But this “good” ozone is gradually being destroyed by man-made chemicals referred to as ozone-depleting substances (ODS), including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, and methyl chloroform. These substances were formerly used and sometimes still are used in coolants, foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants. Once released into the air these ozone-depleting substances degrade very slowly.

Even though we have reduced or eliminated the use of many ODSs, their use in the past can still affect the protective ozone layer. Research indicates that depletion of the “good” ozone layer is being reduced worldwide. Thinning of the protective ozone layer can be observed using satellite measurements, particularly over the Polar Regions.

What Causes “Bad” Ozone?

Ground-level or “bad” ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC.

Incidental Production

Certain electrical equipment generate significant levels of ozone. This is especially true of devices using high voltages, such as ionic air cleaners, laser printers, photocopiers, tasers and arc welders. Electric motors using brushes can generate ozone from repeated sparking inside the unit. Large motors that use brushes, such as those used by elevators or hydraulic pumps, will generate more ozone than smaller motors.


Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground-level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue.

Most people can detect  ozone in air where it has a very specific sharp odor somewhat resembling chlorine bleach. Even low exposure can produces headaches, burning eyes, and irritation to the respiratory passages.

The U.S. Food and Drug Administration has established an ozone level of .05 ppm (parts per million) as the maximum level allowable in an enclosed space intended to be occupied by people for extended periods of time. This includes homes, apartments and office areas.

Contact Shewell Inspections today to find out if the Ozone level in your home is safe.