Article: Ozone in the Workplace

INDUSTRY

Because of its powerful antibacterial activity, ozone gas is used industrially most often as a disinfectant. But it may also be created as a by-product of other processes. Ozone occurs naturally outdoors through the interaction of oxygen (which makes up 20% of the air we breathe) with sunlight. It is in the ultraviolet portion of the sunlight spectrum - particularly a certain wavelength of ultraviolet - that causes oxygen (O2) to convert to ozone (O3). Since oxygen, in air, is everywhere, it takes only a source of ultraviolet light of this frequency to produce ozone. It is also produced when oxygen passes through high voltage AC discharge. So ozone can be easily generated using specially made ultraviolet lights and air or oxygen. And it is also a by-product of many processes where ultraviolet light is used or present.

INDUSTRIAL ENVIRONMENTS WHERE OZONE IS A PROBLEM

Ozone is not just present in the aforementioned ways it is produced, stored in steel or glass bottles, and used in chemicals manufacturing. Because ozone is immediately made whenever ultraviolet light of the proper frequency is shined in air, there are many industrial situations where ozone is created. Many people are familiar with the odor produced around visible electrical sparks; this is the smell of ozone, and ozone is present wherever open sparking occurs.

Ozone, once created, may rapidly dissipate when it comes into contact with surfaces and breaks down. Be aware that ozone, once created, may sometimes drift through the air for long distances, so that if it is not diluted by fresh air, a hazard may exist far from the point of ozone generation. Electric arc welding-particularly gas shielded inert gas "TIG" welding on aluminum - is a common process creating ozone as a by-product, and arc welders are at risk of suffering severe lung injury if they work in areas that have inadequate ventilation.

Arc welding is considered to be the highest-risk occupation because of the high levels of ozone that may be unintentionally generated. Corona devices on photocopy machines allso create small amounts of ozone, although single machines operating properly do not produce sufficient ozone to create a health hazard. But there are many other industries where ozone is, intentionally or unintentionally, produced. Ozone generating ultraviolet lights are made for purifying drinking water and water for swimming pools, hot tubs and spas. Ozone is used as a disinfectant for stored food, animal by products, and sewage.

It is used as a bleaching agent for bleaching textiles and paper pulp. And the manufacture and testing of the ultraviolet lights used to make ozone may itself create hazardous levels of ozone.

HEALTH HAZARDS

Ozone is a colorless invisible gas with a mild odor similar to chlorine bleach. Even in small amounts it is one of the most potently toxic substances known to the lungs. While we all breathe very small amounts of ozone in outdoor air-usually without harm to our lungs-situations in which the level of ozone in air is increased may lead to short term injury or long-term lung damage.

Unfortunately, you can breathe enough ozone to do serious damage to the lungs in a short period of time - seconds to minutes - and without being aware of the exposure, if the levels in air are high enough. And the symptoms that result from breathing th ozone may be delayed for minutes to hours after the exposure occurs. In addition, your sense of smell 'adapts' to ozone rapidly, so that you may smell it when you first walk into a room, but soon become entirely unaware of its presence.

The most frequent effect of overexposure is an episode of cough accompanied by a sense of chest tightness of pain on deep respiration. The cough may last for hours to days. More severe overexposure may result in additional persistent coughing and severe shortness of breath. If you think you may have been exposed to high levels of ozone, you should seek medical attention.

EXPLANATION OF OSHA REQUIREMENTS

The federal Occupational Safety and Health administration regulates the maximum level of ozone permitted in workplace air in the same way that other toxic substances in the workplace are regulated. Violation of the OSHA standard makes the employer liable to fines for noncompliance with standards.

The OSHA Permissible Exposure Limit (PEL) is 0.1 part per million parts of air (0.2 milligrams per cubic meter of air), averaged over an eight hour workday. This level is comparable to outdoor levels that occasionally occur in areas of the country with higher ozone concentrations. One hundred times this level, 10 parts per million, is considered Immediately Dangerous to Life, requiring urgent evacuation of the area.

Even a brief exposure at this level may lead to serious and irreversible lung damage. State Occupational Safety and Health programs must meet or improve upon these protective levels. For temporary situations where the ozone level exceeds the PEL, OSHA recommends specific, fresh-air supplying mask respirators to protect the lungs. Use of mask respirators is meant only for temporary or emergency situations where control of ozone levels in air is not possible.

Use of such respirators in the workplace requires first measuring ozone levels in air to know which design of respirator to use; individual fit testing of each person who will use a respirator; and designating a program maintenance director who will be in charge of storing respirators between use and keeping respirators in proper operating condition.