Filtering Facepiece Respirator Use in Construction
If either identity or concentration of the contaminant cannot be determined, air-purifying respirators such as FFRs cannot be used.
- By Don Garvey
- Mar 01, 2010
Construction workers are frequently exposed to hazardous airborne contaminants such as silica and welding fume, which can cause lung damage, as well as other occupational diseases. Results from a study of construction workers' chest x-rays at Department of Energy (DOE) facilities from 1996 to 2006¹ indicated that, depending on trade, abnormal results were found in 11 to 25 percent of the workers studied. The prevalence of abnormal chest x-ray increased with age and years worked.
When construction workers are exposed to contaminants above the Occupational Exposure Limit (OEL), the employer must take action to control that exposure. While engineering controls are the preferred method, continuously changing conditions, the temporary nature of the work, and required mobility on a construction site can make these difficult if not impossible to implement. Therefore, respirators are frequently the control of choice on construction sites. Because respirators are such a common method of control, it is critical that they be used properly. Improper use can lead to worker overexposure, possible OSHA citations, and, most importantly, workers' potentially suffering needlessly from an occupational disease.
According to a 2003 BLS/NIOSH² study, approximately 77 percent of contractors who used respirators used disposable, filtering facepiece respirators (FFR), or "dust masks." This article will therefore focus on specific items that contractors must be aware of and take into consideration when using these respirators.
The first step to ensure the FFR respirator will provide proper protection is to determine whether it is a proper respirator for the task. If so, contractors must then determine what specific class of FFR can be used.
FFRs are negative pressure, air-purifying respirators. Under NIOSH certification requirements and OSHA regulations, contractors who wish to use these respirators must first identify the contaminant and its airborne concentration. Determination of airborne concentration typically requires on-site air monitoring or use of historical data collected during similar work conditions. This information is reported in units of milligrams per cubic meter (mg/m3) or parts per million (ppm).
Airborne concentration is different than the concentration of the material as reported on its Material Safety Data Sheet (MSDS). The MSDS merely reports the percent (%) of each ingredient in the mixture. While the MSDS can help determine what may be in the air and what to sample for, it cannot be used to determine airborne concentration. If either identity or concentration cannot be determined, air-purifying respirators such as FFRs cannot be used. In this case, OSHA regulations require that supplied air respirators be used.
Assuming contaminant identity and concentration are known, contractors must evaluate the following:
Physical state of contaminant. FFR respirators are for particulates only. They filter solids, such as wood or drywall dust during sawing, and fumes, such as iron oxide from mild steel welding. They cannot be used against gases and vapors, such as carbon monoxide from vehicle exhaust or solvent vapors from coatings applications where the concentration exceeds the current OEL.
Some FFR respirators may be advertised for use against particles and "nuisance" levels of gases and vapors. Nuisance level refers to concentrations below the OEL. These respirators are basically for odor control and worker comfort, rather than respiratory protection against the gas or vapor.
Presence of oil particles or oily substances in the air. If oils or oily materials (e.g., machine oil, cutting fl uids) are present, an FFR respirator with an R (oil resistant) or P (oil proof) rating must be used. If oily substances are not present, an N (non-oil) respirator may be used. R and P respirators may also be used in a non-oil environment.
Filter efficiency. There are three filter efficiencies available: 95, 99, and 100 (99.97) percent efficiency. In basic terms, these numbers refer to the minimum efficiency of the filter when filtering particles with a diameter of 0.3 micrometers mass median aerodynamic diameter (MMAD) at set test conditions. This particle size is in the most difficult particle size range to filter. As the particles get larger or smaller, filter efficiency increases.
At this time, OSHA requires "100" level efficiency filters for use in atmospheres containing lead, arsenic, cadmium, and methylene dianiline. All other particulates (with one exception), including silica and hexavalent chromium, can use either a 95 or 99 percent efficiency FFR. Asbestos is the one other particle for which OSHA requires a 100 percent efficiency respirator filter be used. However, the OSHA asbestos standards explicitly prohibit the use of FFR respirators for protection against asbestos.³
To use the respirator properly, the worker must be properly trained. Ensuring workers are properly trained is the responsibility of the employer. The BLS/NIOSH study indicated only 50 percent of the contractors who used respirators provided training to the level required under current OSHA regulation.
Just as important, the respirator training provider must be trained and knowledgeable. The same study indicated that in 48 percent of the contractor establishments surveyed, the person responsible for the training had no formal education in respirator usage and safety. While an FFR respirator appears to be a fairly simple item, proper use and understanding of its limitations can be complex. The trainer must have a complete knowledge of the specific respirator to be used, how it works, restrictions, warning indicators of improper use, and an understanding of the regulations regarding respirator use in general. Contractors without in-house safety specialists can find training assistance from worker's compensation insurers' loss control representatives, respirator manufacturers' sales and technical staff, and industrial hygiene consultants. Review of the information in the manufacturer's User Instructions should be part of any training program.
Unlike respirator chemical cartridges, particle filters do not have a breakthrough or saturation limitation and are not required to have a mandatory changeout schedule. Manufacturers typically recommend FFR respirators be replaced when they become dirty, damaged, or the wearer notices an increased breathing resistance. One exception to this is the use of "R" respirators, mentioned above, in oily atmospheres. OSHA requires that these be disposed of at the end of each shift, regardless of condition. "P" respirators have no regulatory time limit for use.
The respirator also should be disposed of if the respirator facepiece becomes distorted. This distortion can occur when a worker pinches the respirator to remove it and pulls it down under the chin or up onto the head or hard hat to store it. This distortion and improper storage can prevent a tight respirator face seal and allow contaminants to leak into the respirator or allow the respirator itself to be contaminated.
On a related note, FFR respirators also should not be stored in hard hats between the shell and the head suspension. This storage can prevent the hard hat from functioning properly during an impact and allow injury to the wearer's head or neck.
Other Tips for FFR Respirator Use
- When respirators are required, they must be fit tested. Even in "voluntary use" situations, fit testing is highly recommended. This is done to determine, and document, that the wearer can get a good fit. It is also an important aspect of training because it helps the wearer know how a properly fitted and sealed respirator feels and gives confidence that the respirator will provide protection when worn properly. FFR respirators can be fit tested either quantitatively or qualitatively.
- Both trainers and respirator wearers should review the manufacturer's User Instructions carefully to understand proper use and warnings for the respirator.
- To ensure a proper seal, the user needs to use both straps of the respirator. The top strap must be placed high on the back of the head, not down around the neck with the lower strap. Always follow the manufacturer's donning instructions.
- Exhalation valves can provide increased comfort. Some FFR respirators are equipped with exhalation valves (aka "buttons"). The valve does not affect the protection offered by the respirator but may make the respirator more comfortable to wear because it lets the moist, warm, exhaled air exit the respirator more easily.
- Ensure it is an approved respirator. Respirators must be marked with the manufacturer's logo, "NIOSH," and the level of protection (e.g., N95). Aft er September 2010, respirators also will be required to have the NIOSH "TC" approval number printed on them. If the item does not have these markings, it is not a respirator and should not be used for protection against exposure above the OEL.
- Any and all use of respirators requires that the applicable sections of the OSHA respiratory protection standard, 29 CFR 1910.134, be followed (e.g., the respirator must be maintained in a clean and sanitary condition).
- Mandatory use of FFR respirators (due to exposures above the OEL or employer's requirement as a condition of employment) requires the administration of a full respiratory protection program, which includes medical evaluation for the wearer, training, fit testing, and recordkeeping. For purely voluntary use of FFR (i.e., no overexposures and no employer requirement to wear), medical evaluations and fit testing are optional under current OSHA regulations, but Appendix D of 29 CFR 1910.134 must be provided to all users.
FFR respirators fill an important role in controlling exposures at the construction site. Like any other tool on a construction site, from a hammer to a tower crane, they need to be selected and used properly. With proper selection and use, FFR respirators can provide cost-effective, versatile protection for workers.
References1. The Construction Chart Book--4th Edition (2007). The Center for Construction Research and Training (CPWR).
2. BLS, NIOSH Sept. 2003. Respirator Usage in Private Sector Firms, 2001.
3. 29 CFR 1926.1101 Table 1.
This article originally appeared in the March 2010 issue of Occupational Health & Safety.