Atmospheric Hazards

• Oxygen deficient atmosphere below 19.5% oxygen. Develop when oxygen is displaced by other gases or depleted through biological or chemical processes.

• Particulates (dust, mists, fumes, fibers).
  • Dusts are solid particles (e.g., silica).
  • Mists are liquid condensation particles (e.g., acid mist, fog).
  • Fumes are solid condensation particle < 1 m diameter (e.g., welding / metal cutting fumes).
  • Fibers are solid particle with an aspect ratio 3:1 (e.g., asbestos).
  •  
• Toxicants

• Asphyxiants
  • Simple asphyxiants: displace oxygen (e.g., nitrogen, methane).
  • Chemical asphyxiants: chemically prohibit the uptake of oxygen (e.g., carbon monoxide, cyanide).
• Irritants: irritate tissues (e.g., ammonia, chlorine).

• Allergens: cause allergic reactions (e.g., isocyanates, sulfur dioxide).

• Carcinogens: cause tumors to form (e.g., benzene, cigarette smoke)

Respiratory Protection Program

• Persons should not be assigned to tasks requiring use of respirators unless it has been determined that they are physically able to perform the work and use the equipment.

• Equipment must be NIOSH and MSHA approved.
• Men are no longer permitted to have facial hair between the respirator seal and skin.  This hair must be shaved.

Classes of Respirators

Air-Purifying Respirators

Supplied-Air Respirators

• Use adsorbing or absorbing disposable canisters

• Have negative pressure (if there is a leak around the seal, contaminated air will take the path of least resistance and enter around the seal and not be filtered by the canisters)

• Powered air purifying respirators use a blower to pass the contaminated air through a filter.

• Positive pressure for better protection against chemicals

• Use full face masks for eye protection

• Use clean air from outside source

• Used in levels A and B.

Half Face Respirator

• Provides a maximum protection factor of 10

• Provides no eye protection

• Convenient to use and inexpensive (< $50)

Self-Contained Breathing Apparatus (SCBA)

• Provides a high protection factor (10000)

• Air supply up to 60 minutes

• Aluminum (heavier, inexpensive) or composite (lighter, expensive) tanks available

Full Face

• Provides a maximum protection factor of 50

• Provides eye protection

• Convenient to use, moderately inexpensive ($100 - 200)

Air-line

• Air supply from large, cascading cylinders or special, oil-free Grade D compressor

• Air supply is effectively unlimited

• Needs an escape bottle for backup.

Canister Selection

(Cartridge Color - Effectively Purifies)

White - Acid gas

Black - Organic vapors

Green - Ammonia gas

Yellow - Acid gas and organic vapors

Magenta - Radioactive materials, particulates

Orange - Dust, fumes, and mists

Olive - Other gases and vapors

Corrective Eyewear Options

• Glasses with short temple bars or without temple bars may be taped to the wearer's head

• Mount corrective lenses inside face piece (full face)

The use of contact lenses while wearing a respirator in contaminated environments is now allowed effective 1998.

Respirator Donning

1. Clean mask
2. Make sure straps are loose
3. Don mask. Tighten straps in pairs
4. Hold hand over exhalation valve and exhaling for 10 seconds. Mask should maintain internal pressure.
5. Hold hands over cartridges and inhale. Mask should hold a vacuum.

Respirator Doffing

1. Relax straps
2. Remove mask
3. Inspect and clean

Respirator Fit-Testing Protocols

Qualitative & Quantitative are acceptable

Qualitative

Quantitative

• Bitrex®
• Irritant Smoke
• Amyl-Acetate (Banana Oil)

Talk, turn head side to side and up and down to check facial seal. If you can smell the smoke, Bitrex® or banana oil you do not have a good fit and need to try brand or size of respirator.

Some specific contaminants listed in 29 CFR 1910 require their own qualitative fit test procedures.

• Determines protection factor (concentration of atmosphere contaminant divided by concentration of contaminant in breathing zone)

• Expensive to perfrom

Respirator Fit-Testing

• The employer should have a selection of respirators for the employee to choose from, including different sizes and brands

• Employer should supply respirator, although the employer may require that employee purchase his/her own respirator

Protection Factors

NIOSH has assigned protection factors to the four respiratory equipment styles.

Protection factor x Safe Concentration = allowable working environment.

Half face

SCBA

Factor

10

50

2000

10,000

Breathing Zone Concentration

Ambient Concentration / 10

Ambient Concentration / 50

Ambient Concentration / 2000

Ambient Concentration / 10,000

Chemical Cartridge Prohibitions

• Acrolein

• Aniline

• Arsine

• Bromine

• Carbon Monoxide

• Dimethyl Aniline

• Dimethyl Sulfate

• Hydrogen Cyanide

• Hydrogen Fluoride

• Hydrogen Selenide

• Hydrogen Sulfide

• Methanol

• Methyl Bromide

• Methyl Chloride

• Methylene Bisphenyl

• Nickel Carbonyl

• Nitrobenzene

• Nitrogen Oxides

• Nitroglycerin

• Nitromethane

• Ozone

• Phosgene

• Phosphine

• Phosphorus Trichloride

• Stibine

• Sulfur Chloride

• Toluene Diisocyanate (TDI)

• Vinyl Chloride

Cartridge Durations

• For HEPA cartridges, replace when breathing is impaired

• For adsorbing cartridges, replace when:
  • Odor is detected through cartridge, if the odor threshold (available from CHRIS Manual) < safe concentration,
  • 1% breakthrough, for all other chemicals.

Effect of Solvent Vapor on Respirator Cartridge Efficiency

Examples

Solvent

Aromatics

Benzene

Toluene

73

94

Methanol

Ethanol

.2

28

Methyl Chloride

Vinyl Chloride

0.05

3.8

Dichloromethane

o-Dichlorobenzen

10

109

Chloroform

Methyl Chloroform

33

40

Carbon Tetrachloride

Perchloroethylene

77

107