Respiratory Protection in Drinking Water Plants
By Henry G. Nowicki, Ph.D., and Barbara Sherman
Summary: OSHA’s most cited health and safety violation in water utilities is poor respiratory protection. This article discusses how the issue applies to drinking water applications and precautions that can be taken.
Airborne hazards are a fact of life in many drinking water plants and chemical manufacturing facilities. Various chemicals used for treating water can emit noxious and sometimes dangerous vapors and dust particles that can harm or even kill operators.
Since 1972, the Occupational Safety and Health Administration (OSHA) has inspected more than 5,100 public drinking water systems. Between October 1998 and September 1999, inspectors issued 506 citations for health and safety violations. Of those, the most cited violation was for poor respiratory protection practices at the water utilities.
OSHA law for respiratory protection
The law requires employers to provide respiratory protection to employees exposed to concentrations of potentially harmful substances exceeding established Permissible Exposure Limits (PELs). PELs are vapor concentrations that have no adverse effects on exposure to young healthy adult males. Sub-groups of unhealthy, older and pregnant women should limit their exposure to toxic gases and vapors below the PELs. Don’t rely on the employee’s ability to sense the odor of a substance. Some chemicals have odors only detectable above their established exposure limits, meaning the employees will smell the chemical only after they’ve already been exposed to unsafe levels of the contaminant. Many vapors, such as the rotten egg smell of hydrogen sulfide, inhibit the olfactory response; thus, exposed employees lose the sensory ability to smell it after inhaling the vapor. The point of the law isn’t to simply force more regulations on utilities, but to prevent deaths and illnesses among employees by protecting them from exposure to acute and chronic health hazards.
The workplace is always monitored to ensure maximum exposure limits aren’t exceeded if the presence of a harmful substance cannot definitely be excluded.
Essentially these maximum exposure limits are given for approximately 400 substances such as:
- Long-Term Exposure Limit expressed as an 8-hour Time Weighted Average, or
- Short-Term Exposure Limit expressed as a special fixed concentration
From country to country, there are different definitions of the short-term exposure limit values. They may normally occur in a limited duration and frequency per shift. The magnitude of the maximum exposure limits results from the respective legislation of the individual countries. They are consulted as a clear evaluation standard for the evaluation of a workplace. Definitions for occupational exposure are presented in the enclosed Table—“Definitions for Industrial Hygiene Exposure.”
Dusts, fumes, gasses or vapors, and temperature extremes can penetrate and damage the respiratory system. Dust and fumes can irritate the nose and throat and, in some cases, the lungs. Gasses and vapors can be absorbed from the lungs into the bloodstream, where they have the potential to damage the brain and internal organs. Very hot or cold air can damage the fine tissues in your mouth and airway, and interfere with normal breathing.
Getting the right respiratory protection and proper use
There are several ways to protect against exposure to airborne contaminants. Usually, engineering and administrative controls provide sufficient protection. Engineering controls include such things as increasing ventilation or installing a fume hood; administrative controls involve changes in work procedures that lessen or eliminate exposure, or substitute non-hazardous materials for the materials that pose respiratory hazards. The law requires that managers consider these controls before issuing employees respirators. If engineering and administrative controls aren’t feasible or won’t provide adequate protection, respirators can then be assigned.
According to OSHA, respirators should only be used as part of a complete written respirator program run by a “respirator program administrator.” A respirator program includes:
- Evaluating exposures in the workplace to determine their nature and concentration (an industrial hygienist usually performs this);
- Conducting a medical evaluation of employees who must use respirators;
- Selecting the appropriate respirator based on air measurements and exposure limits for each contaminant;
- Training employees to use the respirator properly;
- Fit testing the equipment. It’s important respirators fit the user’s face without excessive leakage around the face seal. Each user needs to use an adequately fitting respirator and make sure the best possible face seal is achieved each time it’s worn. Men must be clean-shaven to wear a respirator correctly. Most respirators won’t provide the necessary tight seal over a beard;
- Requiring that one never uses another person’s respirator. If used according to the manufacturer recommendations, each respirator should be specifically fitted to the person designated to wear it;
- Providing guidance for properly maintaining, cleaning and storing respirators.
Engineering and administrative controls are always preferable to using a respirator. Respirators should only be considered if no other solutions are viable, since the possibility for human error makes the respirator less reliable than the other controls.
Respirator types & practices
There are two major respirator types—air-purifying and atmosphere-supplying.
Air-purifying respirators—These remove contaminants from the air. They work by screening out or trapping contaminants in filter cartridges. They may be disposable or have a reusable face piece that allows filters or cartridges to be replaced. Some are catalytic and convert a toxic to a non-toxic.
Atmosphere-supplying respirators—These provide clean air from an uncontaminated source. They may be either a self-contained unit, such as a portable air tank that’s carried, or they may use an air line attached to a user’s hood or mask and an outside air tank.
Don’t buy or use a respirator without making sure it’s made to protect the user against the contaminants likely faced in the work environment. Respirators are designed to protect against different hazards for specified periods of concentration and time. A filter cartridge has a defined capacity and must be refreshed with a new filter to prevent breakthrough and employee exposure. Never assume a respirator can handle all contaminants. Precautions against over-reliance on respirators should be covered by the employer-training program.
Don’t wear a respirator into a situation that hasn’t been designated for the cartridge you’re using. Different environmental hazards may require a change in assigned cartridges or respirators. No single cartridge respirator is good for all situations.
Special precautions need to be taken when entering vessels containing moist activated carbon. Carbon can remove oxygen in a closed air space resulting in death of the operators. Having an oxygen monitor and buddy outside the vessel with an atmosphere-supplying respirator would help provide the needed safety for operators in closed spaces.
Both the employee and the employee’s supervisor have legal responsibilities to ensure that respirators are used properly.
The employee must:
- Return for annual fitting,
- Use the respirator only for the assigned hazard and clean and maintain the respirator as trained, and
- Notify the supervisor of any new or changed workplace hazard.
- The employee’s supervisor must:
- Identify employees who may need respiratory protection,
- Ensure the employee is in the Respiratory Protection Program and is properly using, storing, cleaning and maintaining their respirator, and
- Periodically discuss proper respirator use during safety briefings.
Before the employer assigns an employee a respirator, several things must be done, including trying to solve the problem through engineering and administrative controls first; determining exposure hazards; getting the correct respirator; screening staff with medical tests; fit testing equipment; providing ongoing maintenance and training in operation of the respirators, and conducting annual re-fitting tests.
There’s no required replacement schedule for respirators in general; however, damaged respirators cannot properly protect employees. Respirators need to be replaced or repaired when one or more of their components is missing, damaged or visibly deteriorated.
About the authors
Dr. Henry Nowicki directs PACS Inc., of Pittsburgh, a laboratory testing and consulting service. He is a member of WC&P’s Technical Review Committee.
Barbara Sherman directs the PACS courses and conference services. Available PACS courses related to this article are toxicology and OSHA laboratory standard. Both authors can be reached at (724) 457-6576 or email: HNpacs@aol.com