Introduction
N95 respirators “are examples of personal protective equipment that are used to protect the wearer from particles or from liquid contaminating the face” [1]. Also, “Most N95 respirators are manufactured for use in construction and other industrial type jobs that expose workers to dust and small particles. They are regulated by the National Personal Protective Technology Laboratory (NPPTL) in the National Institute for Occupational Safety and Health (NIOSH), which is part of the Centers for Disease Control and Prevention (CDC)” [1]. We’ve become familiar with these respirators as a result of the COVID-19 pandemic. N95s have a certain filtration capacity, which distinguishes them from standard hospital face masks or cotton masks that are common-use amongst regular people nowadays.
Usage
N95s can come with or without exhalation valves, both are acceptable in painting applications. “All FDA-cleared N95 respirators are labeled as "single-use," disposable devices. If your respirator is damaged or soiled, or if breathing becomes difficult, you should remove the respirator, discard it properly, and replace it with a new one” [1]. When it comes to painting, these products can be reused as often as needed until certain components begin to fail, which affects their safety (i.e. loss of the piece near the nose that allows the mask to more closely hug the face, loss of a strap holding the mask in place, small, visible holes and perforations in the material). In order to achieve a tight fit, the user should not have facial hair. When putting on a respirator, deal a user seal check by placing hands over the respirator and exhaling. If air leaks around the nose, readjust the nosepiece. Do not work without a proper seal [2]. See [2] for visual clarifications. Respirators that are not NIOSH certified shouldn’t be used, since their production standards are not guaranteed to a clear standard [4].
Protective Filter
The product is appropriate for “Particles such as those from sanding….Liquid or non-oil based particles from sprays that do not also emit oil aerosols or vapors” [3]. N95s should not be used for “Gases and vapors….. asbestos, arsenic, cadmium, lead, 4,4’-methylene dianiline (MDA) or sandblasting….or when concentrations of a particular ingredient exceed 10 times the permissible exposure limit (PEL)...... [3]. N95 respirators have filtration efficiencies that depend on the size of the particles they protect against. For those particles (0.1 to 0.3 microns), n95s are at least 95% efficient. Efficiency reaches 99.5% or higher with particles of 0.75 microns in size [5].
Regarding particle sizes from sanding, one study looking at paint with nanoparticles and results of sanding these paints found that “the sander was a main source of particles smaller than 50 nm. Total emission number size distributions were clearly five modal. The First two modes had peaks below 20 nm and these were identified as sander emissions. Mode 3 was found at about 200 nm, which contained particles from the sander and paint dust emissions. Mode 4 and 5 were at 1 and 2 µm and they contained mostly dust released from the paints“ [6]. This seems to indicate that with paints containing nanoparticles, there’s a potential spread from 20 nm to 2µm, which converts to 0.02 to 2 microns (n95 protects for a minimum of 95% of particles down to 0.1 microns).
Regarding paint vapors, an anonymous, home improvement forum post states that “VOCs are not particles of "stuff" so a particulate filter (N95, P95, Etc) does not help with them. This means a typical size in microns is also irrelevant because you are dealing with molecular size when it comes to vapors” [6].
Exposure thresholds to certain potentially harmful ingredients in a paint can range (in this case a Behr product), for example from 3mg/cubic meter to 20 mg/cubic meter [8].
When it comes to sanding activities and occupational exposure, one study reports that when it comes to wood, “Occupations with high exposure to wood dust included sander in the transportation equipment industry (unadjusted geometric mean = 17.5 mg/m3), press operator in the wood products industry (12.3 mg/m3), lathe operator in the furniture industry (7.46 mg/m3), and sander in the wood cabinet industry (5.83 mg/m3)” [9].
Analysis and Conclusion
The following analysis is my opinion based on what I’ve just read.
With regard to sanding surfaces, N95s are not acceptable when it comes to highly toxic materials like lead and asbestos. The filters ultimately allow for a certain amount of an ingredient to bleed through. Their range of protection is only 95% and only from 0.1 microns (100 nanometers or nm) or higher. N95s are appropriate for sanding and cleanup of ingredients that produce dust 0.1 microns/micrometers or higher. They are not appropriate for ingredients that contain nanoparticles smaller than 0.1 microns. It’s not possible to tell, without doing some research, whether the surfaces someone is sanding contain tiny particles or not.
With regard to vapors that come from paint cans, N95s are not acceptable because they do not protect against organic vapors. Thus, n95s are appropriate for sanding and cleanup activities, but not for painting. A different painting respirator should be used for that. An n95 respirator is also not appropriate for spray painting activities, which produce breathable vapors.
In terms of best approaches when working, painters should always wear n95 masks when engaged in sweeping or sanding. Whenever possible, it is best to avoid sanding. When painting or rolling, painters should always wear painting respirators, a topic that’ll be discussed in a separate blog post.
References
Comments