Respiratory Protection: The Right Respirator

The Occupational Safety and Health Administration/Virginia Occupational Safety and Health (OSHA/VOSH) regulation 29 CFR 1910.134, Respiratory Protection, requires employers to evaluate workplaces to determine if there are any respiratory hazards present. If respiratory hazards are found, then employers are responsible for

• Providing a written program with workplace-specific procedures,
• Identifying a qualified individual to oversee the program,
• Determining respiratory hazards in the workplace,
• Providing medical evaluations to employees required to wear respirators,
• Providing training to employees, and
• Fit-testing employees annually.

OSHA/VOSH defines the following as forms of respiratory hazards that may be present in the workplace:

• Dusts and fibers - solid particles that are formed or generated from solid materials through mechanical processes such as crushing, grinding, drilling, abrading, or blasting. Examples are lead, silica, and asbestos.
• Fumes - solid particles that are formed when a metal or other solid vaporizes and the molecules condense (or solidify) in cool air. Examples are metal fumes from smelting or welding. Fumes also may be formed from processes such as plastic injection or extrusion molding.
• Mists - tiny droplets of liquid suspended in the air. Examples are oil mists produced from lubricants used in metal cutting operations, acid mists from electroplating, and paint spray mist from spraying operations.
• Gases - materials that exist as individual molecules in the air at room temperature. Examples are welding gases, such as acetylene and nitrogen, and carbon monoxide produced from internal combustion engines.
• Vapors - the gaseous forms of substances that are normally in the solid or liquid state at room temperature and pressure. They are formed by evaporation. Most solvents produce vapors. Examples include toluene and methylene chloride.
• Biological hazards include bacteria, viruses, fungi, and other living organisms that can cause acute and chronic infections if inhaled. Examples include Legionnaire’s Disease, flour, and animal products (dander, excreta).¹

The two types of respirators are air-purifying and air-supplying. Air-purifying respirators work by filtering particles or chemicals from the air. These respirators are known as particulate respirators, gas mask/chemical cartridge respirators, and powered air-purifying respirators (PAPR). Air-supplying respirators work by supplying clean air to the wearer from an outside source. These respirators are Self-Contained Breathing Apparatus (SCBA) and supplied-air respirators.

Air Purifying

Particulate respirators filter out dust, fumes, and mists. These respirators do not protect the employee from chemicals, gases, vapors, or oxygen deficient atmospheres. Quarter face respirators are commonly referred to as “dust masks or N-95.” However, half-face mask respirators with a filter unit can also be a particulate respirator. The major limitation with this type of respirator is the employee. The employee must be trained to recognize when the respirator is damaged, clogged, or when the resistance to air flow is decreased. This type of respirator is most commonly used in dusty environments (wood working shops), in hospital settings (infectious agents), and lawn maintenance (cutting grass).

Gas Masks/Chemical Cartridge Respirators filter or clean chemical gases or vapors out of the air that the employee breathes through a canister or cartridge. This type of respirator does not protect the employee from oxygen deficient atmospheres, very toxic substances, or substances that cannot be detected by smell or taste. The difference between a canister and cartridge is the outer shell that houses the filter media. Canisters have metal outer shells and cartridges have either plastic or cloth shells.²

Gas masks/chemical cartridge respirators can be half-face, full-face, hoods, or helmets with a canister or cartridge attached on the front or chin area of the mask. The respirator is secured to the head with a series of straps. It is important that the right canister/cartridge be selected based on what vapor or gas will be present. No “generic” canister/cartridge exists that filters out all substances. Multiple canisters/cartridges maybe required to protect the employee. There are combo canister/cartridges available for multiple exposures.

The major limitation with this type of respirator is the canister/cartridge. The correct type must be determined based on the employee’s exposure. Additionally, the canister/cartridge has a shelf and usage life. The amount and time the employee is exposed to the hazard will determine how long the canister/cartridge is good. A change out or replacement schedule needs to be developed. This type of respirator is most commonly used with pesticide application, biological weapons, exposure to heavy metals, spray booths, working around chlorine, and strike force operations.

Powered Air-Purifying Respirators are very similar to gas mask/chemical cartridge respirators; however, a fan is used to blow air through the filter to the employee. It has the same limitations as the gas mask/chemical cartridge respirator and requires a fully charged battery. Battery usage and charging is an additional limitation.

Air Supplying

Self-Contained Breathing Apparatus (SCBA) provides protection in toxic atmospheres as well as oxygen deficient atmospheres. The employee carries a supply of air in a tank on his or her back. There are several limitations to this type of respirator including weight, bulk and limited air supply. Specialized training on proper use and maintenance is also required. This type of respirator is commonly used with rescue operations, especially by firefighters. SCBAs are also used in wastewater treatment plants and with some heating and cooling systems that use ammonia.

Supplied-Air Respirators provide the same protection as the SCBA; however, the employee does not wear a tank and instead receives air through a hose. There are three categories: hose mask with blower, hose mask without blower, and air-line respirator. This type of respirator should be used in environments that are immediately dangerous to life and health (IDLH). The air-line respirator is the most effective, is lightweight and provides the best protection for long-term use. The limitation to this type of respirator is the hose itself. It can become a nuisance or hazard if cut, blocked, pinched, or obstructed and the air is unable to reach the employee. Special consideration should be given to the placement of the air intake so that combustion by-products do not contaminant the air.

Filter Classes

The respirator alone does not provide protection to the employee from the substances to which he or she is exposed; it is the respirator plus the filter, canister, or cartridge that provides protection. Particulate filters can be broken into nine classes of filters. “There are three levels of filter efficiency, with three categories of resistance to filter efficiency degradation. The three levels of filter efficiency are 95%, 99%, and 99.97%. The three categories of resistance to filter efficiency degradation are labeled N (Not resistant to oil), R (Resistant to oil), and P (oil Proof). R- or P-series filters can be used for protection against oil or non-oil aerosols. N-series filters should be used only for non-oil aerosols.”³

Canisters and cartridges are assigned a color-coding system based on the type of substance they filter. The chart below represents some most common types of canisters/cartridges that are used.

Using the information provided in this article, review the hazards and employee exposure at the agency to determine if the right respirator and canister/cartridge are being used. If additional help is needed, contact Workers’ Compensation Services Loss Control at 804-225-2799.

¹ NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84. ² Small Entity Compliance Guide for the revised Respiratory Protection Standard. ³ NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84. ⁴ “OSHA Bulletin: General Respiratory Protection Guidance for Employers and Workers.”

References

National Institute for Occupational Safety and Health. (n.d.). NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84. Retrieved March 8, 2006, from http://www.cdc.gov/niosh/userguid.html.

National Institute for Occupational Safety and Health. (n.d.). “Respirator Fact Sheet.” Retrieved March 8, 2006, from http://www.cdc.gov/niosh/npptl/topics/respirators/.

U.S. Department of Labor, Occupational Safety and Health Administration. (n.d.). “OSHA Bulletin: General Respiratory Protection Guidance for Employers and Workers.” Retrieved March 8, 2006, from http://www.osha.gov/dts/shib/respiratory_protection.pdf.

U.S. Department of Labor, Occupational Safety and Health Administration. (1998). “Respiratory Protection eTool.” Retrieved March 8, 2006, from http://www.osha.gov/SLTC/etools/respiratory

U.S. Department of Labor, Occupational Safety and Health Administration. (1998). Small Entity Compliance Guide for the revised Respiratory Protection Standard. Retrieved March 8, 2006 from http://www.osha.gov/Publications/SECG_RPS/secgrev-current.pdf.

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