CASCADIAN^®
Professional Water Treatment Products

O₃ Water Systems, Inc.
17700 147th St SE
Suite F
Monroe, WA 98272
USA

Phone: 360-794-9511
Fax: 360-794-0856

EPA SAFETY GUIDELINES

Safety

Ozone is a toxic gas, and like chlorine can cause severe illness and death if inhaled in sufficient quantity. However, ozone systems have safety advantages not available with the chlorine disinfection process. Ozone is generated on-site, thus eliminating transportation hazards. Also, the generation system can be shut down it an ozone leak develops. Another safety advantage is the physical characteristic of ozone that allows it to be detected (smelled) at concentrations much lower than harmful levels.

In addition to safety precautions against exposure to ozone, protection against noise and electrical hazards should be incorporated into the design and operation of an ozone disinfection system.

Recommended Exposure Limit to Ozone

A study of the health effects of ozone exposure was conducted by the United States Air Force. Another summary of the health effects of ozone was compiled by the American Society for Testing and Materials (ASTM) in support at their recommended standard for limiting human exposure to ozone. The reported biological effects range from dryness of mouth and throat, coughing, headache, and chest restrictions at concentrations near the recommended limit, to more acute problems at higher concentrations.

The recommended ambient ozone exposure levels have been proposed by the Occupational Safety and Health Administration (OSHA), the American National Standards Institute/American Society for Testing and Materials (ANSI/ASTM), the American Conference of Governmental Industrial Hygienists (ACGIH), and the American Industrial Hygiene Association (AIHA) as follows:

Control occupational exposure such that workers will not be exposed to ozone concentrations in excess of a time weighted average of 0.2 mg/m³ (0.1 ppm by volume) for eight hours or more per workday, and that no worker be exposed to a ceiling concentration of ozone in excess of 0.6 mg/rn³ (0.3 ppm by volume) for more man 10 minutes. These recommended limits for ozone concentration are much higher than the concentrations at which ozone can typically be smelled. Generally, an individual can detect ozone at concentrations ranging from 0.02 to 0.1 mg/rn³ (0.01 to 0.05 ppm by volume). The more often a person is exposed to ozone the higher the required concentration for detection.

Ambient Ozone Concentration Monitors

The subject of safety in the design and operation of an ozone system should receive a high priority. All ozone systems should be provided with an ambient ozone monitor or monitors which are set up to measure the ozone concentration at potential ozone-contaminated locations within the plant (e.g., at various places in the room housing the ozone generators). A single monitor may be installed and the air from different locations pumped to the monitor for detection of ozone concentration. The monitors should be set up to sound an alarm when the ozone concentration reaches 0.2 mg/l (0.1 ppm by volume), and should be set up to shut down the ozone system when the concentration exceeds 0.6 mg/l (0.3 ppm by volume). However, if the ozone equipment is located in an area where "smoggy" days due to ozone levels in the atmosphere are common, higher values may be necessary to be able to detect ozone leakage by the ozone generation system.

A listing of reliable ozone monitors used for ambient monitoring purposes may be obtained from the ozone generation equipment manufacturers and from operating plants. These monitors may be checked and calibrated using extensive calibration procedures₁ but loss of calibration typically has not been a problem. Under normal operating conditions the monitor does not "alarm" and the operators cannot smell ozone. Therefore, on a periodic basis the operators should check the operation of the monitor by directing a small volume of ozone from the generator to the monitor to test the meter's responsiveness. In this manner the operators can be assured that the monitor will respond in case of an ozone leak.