7.2 Respiratory Protection

Inhalation exposure is easy to underestimate in Oklahoma work. A Category 7A technician fogging a restaurant storeroom, a turf applicator in an open cab with a blowing wettable powder, and a mixer leaning over an inductor of solvent-based concentrate are all breathing different mixtures of droplets, dust, and vapor. The label, not habit, names whether you need a respirator and which NIOSH (National Institute for Occupational Safety and Health) assembly is acceptable. Nuisance dust masks and many surgical masks are not NIOSH-approved respirators for labeled pesticide use.

Atmosphere-supplying versus air-purifying

Atmosphere-supplying respirators deliver clean air from a tank or a remote compressor. A self-contained breathing apparatus (SCBA) carries the air on your back (NIOSH prefix TC-13F). A supplied-air respirator (prefix TC-19C) feeds air through a hose; some labels require an escape bottle as well. These devices belong where oxygen is low or the atmosphere may be immediately dangerous to life or health, including many structural fumigations. Oklahoma fumigation certification is its own category. Do not walk a 7A general-pest route with an SCBA because a social-media video looked dramatic, and do not enter a labeled IDLH space with a cartridge respirator because the SCBA is at the shop.

Air-purifying respirators (APRs) pull the surrounding air through filters, cartridges, or canisters. They do not add oxygen. Never use them in oxygen-deficient or IDLH air.

Within APRs you will see:

• Filtering facepiece (often called a dust/mist respirator): the whole facepiece is the filter. Common for particulates only. Still a tight-fitting respirator when NIOSH-approved.
• Half-face elastomeric: covers nose and mouth; used with replaceable cartridges and filters. Needs separate eyewear if the label requires eye protection.
• Full-face elastomeric: covers eyes, nose, and mouth; can satisfy labeled protective eyewear when it is a full-face respirator.
• Powered air-purifying respirator (PAPR): a blower pushes air through purifying elements into a tight-fitting facepiece or a loose-fitting hood or helmet.
• Gas mask with canister: higher-capacity sorbent than a cartridge (prefix TC-14G).

NIOSH TC numbers and purifying elements

Labels cite a TC (testing and certification) prefix. National Core maps the common pesticide prefixes this way:

• TC-84A: filtering facepieces (N, R, or P); nonpowered APRs with particulate filters; nonpowered APRs with combination chemical cartridges and N, R, or P filters.
• TC-21C: PAPR with a high-efficiency (HE) particulate filter.
• TC-23C: APR with chemical cartridges; PAPR with chemical cartridges; PAPR with combination chemical cartridge and HE filter.
• TC-14G: gas mask with or without particulate filter; some tight-fitting PAPRs with canisters.
• TC-13F: SCBA, and supplied-air units with a self-contained escape bottle.
• TC-19C: supplied-air respirator.

A typical pesticide sentence looks like: wear a NIOSH-approved respirator with an organic-vapor (OV) cartridge and any N, R, or P filter, prefix TC-84A; or a PAPR with OV cartridge and HE filter, prefix TC-23C; or a gas mask with OV canister, prefix TC-14G. You must use an assembly that matches one of those complete options. Do not mix facepieces, cartridges, and filters across manufacturers; the NIOSH approval is for a listed assembly.

Particulate filters capture dusts, mists, and sprays. They do not remove gases or vapors. Nonpowered filters carry two ratings: oil behavior and efficiency. N means not oil resistant. R means oil resistant for up to eight hours of use in oily aerosol. P means oil-proof. Efficiency is 95, 99, or 100 (lower leakage at higher numbers). If the tank mix includes oil or an adjuvant that behaves like oil, do not use N-series filters. PAPR particulate elements are HE, not N95.

Organic-vapor cartridges and canisters use sorbent to take up specified gases and vapors. They do not remove particulates. Most pesticide labels that address vapor name OV elements. If the product can present both spray droplets and vapor—an indoor aerosol, an EC mix/load, a dust that off-gasses—the label often requires a combination OV cartridge plus a particulate filter, either stacked with a retaining ring or built as one combo cartridge.

Change-out, breakthrough, and end of service life

Chemical cartridges are effectively all-or-nothing until breakthrough. Taste, smell, or irritation inside the mask means the sorbent is spent or the facepiece is leaking. Leave the area on clean air, then replace the elements and check the seal. Do not keep working to finish a city block. National Core teaching is to dispose of used OV cartridges at the end of the workday unless the manufacturer directs otherwise, because trapped vapor can desorb overnight and dose you the next morning. Do not reuse a cartridge that sat open in a hot truck cab.

Particulate filters load until breathing resistance rises, the filter is damaged or soiled, or you hit the label or manufacturer change schedule. EPA-style default when no other direction exists: discard particulate filters after eight hours of cumulative use. Dirty filters cannot be washed. Handle them as contaminated PPE.

If a combo cartridge breaks through on the vapor side, replace the whole purifying element even if the filter still looks clean. Follow whichever limit arrives first: manufacturer end-of-service-life indicator or schedule, pesticide label, breakthrough, soil, or damage.

Medical evaluation, fit testing, and the user seal check

A tight-fitting respirator is a physiological load: extra breathing resistance, heat, and dead-air space. Before a handler uses a label-required respirator, WPS (40 CFR 170.507) requires the handler employer to provide three protections that follow OSHA's 29 CFR 1910.134 framework:

1. A medical evaluation by a physician or other licensed health-care professional, using the OSHA-style questionnaire and any needed follow-up exam, to confirm the person can wear that respirator safely. The evaluation comes before fit testing and before use. It applies to filtering facepieces as well as elastomeric and powered units.
2. Fit testing with the same make, model, style, and size the handler will wear, before first use and at least annually, and again after a change in face shape (weight change, dental work, scarring, cosmetic surgery) or a change of facepiece.
3. Training in use of that respirator, also on the OSHA topics incorporated by WPS, before use and at least annually thereafter.

The employer keeps records of those three items on the establishment for two years. Oklahoma does not issue a separate pesticide respirator license through the Oklahoma Department of Agriculture, Food, and Forestry (ODAFF). Certification as a commercial or non-commercial applicator is not a substitute for the WPS medical evaluation, fit test, or respirator training when the label requires a respirator. Agricultural WPS applies on covered establishments (farms, forests, nurseries, greenhouses). Indoor 7A and many right-of-way jobs may sit outside WPS, but OSHA respiratory rules can still apply to employees, and the label still requires the named respirator. Do not skip medical clearance and fit testing because the site is a restaurant instead of a wheat field.

Qualitative fit testing uses a challenge agent you can taste or smell (such as saccharin or Bitrex) or an irritant smoke protocol where allowed. If you detect the agent, the facepiece leaks. Quantitative fit testing uses an instrument to measure a fit factor. Either method is a fit test. Neither is a user seal check.

Perform a user seal check every time you don a tight-fitting respirator, including a filtering facepiece:

• Positive-pressure check: cover the exhalation valve, exhale gently, and feel for leakage at the seal.
• Negative-pressure check: cover the inlets, inhale, and feel the facepiece collapse without incoming leaks.

Failing a seal check means you do not enter the treated air. Adjust straps, replace valves, or select another fitted size. Facial hair that sits in the sealing surface—beard, stubble, wide mustache—prevents a reliable seal. Tightening straps until it hurts does not fix a beard. A loose-fitting PAPR hood that the label allows does not need a fit test and can work for people who cannot shave, provided it is the labeled TC type and you still complete medical evaluation and training when WPS or OSHA requires them.

Store the respirator in a clean bag away from concentrates. Distorted facepieces leak. Cartridges left unsealed in a pesticide truck adsorb whatever vapor is in that cab.

Oklahoma pictures again: a 7A indoor fog may list a combo OV-plus-P100 full-face (TC-84A) because droplets and vapor both matter in a closed room. A wettable-powder turf load on a windy shop pad may list a particulate respirator only. A phosphide fumigant is a different world of canisters or SCBA. Match the task sentence on that label. You may wear a higher-protection assembly when it still meets the named TC option; you may not wear a dust/mist filtering facepiece when the label requires OV cartridges.