oil and gas: Respiratory Protection

The National Institute for Occupational Safety and Health (NIOSH) has examined the criteria for respirator tests and sources of respirator leakage and recommends that positive pressure, either supplied-air or self-contained breathing apparatus, as appropriate, with a full face piece be worn by

anyone exposed to atmosphere containing hydrogen sulfide concentrations above OSHA's ACC (refer to 29 Code of Federal Regulations Part 1910.1000, Subpart Z, Table Z-2) Refer to Par. 6.4 for proper breathing equipment recommendations for oil and gas producing and gas processing plant operations involving hydrogen sulfide.

Note: There are differences of opinion in the medical community about whether a person with a perforated eardrum can become overexposed to a toxic substance via the ear, even when wearing proper personal breathing apparatus, and whether they should be excluded from work in a hydrogen sulfide environment'-". Theoretical calculations by Richard Ronk and M. K. White'-'' have led the authors to conclude that tympanic membrane (eardrum) defects do not significantly compromise respiratory protection against hydrogen sulfide and that individuals with perforated tympanic membranes should not be excluded from work in a hydrogen sulfide environment. The validity of these calculations is supported by the absence of case reports of hydrogen sulfide poisoning due to tympanic membrane defect.

Ronk and White'-" also concluded that wearers of positive-pressure, either supplied-air or self-contained personal breathing apparatus, with a full face piece, as recommended by the National Institute for Occupational Safety and Health (NIOSH), who have a tympanic membrane defect and a concurrent rympanomaxillary shunt or a patulous eustachian tube (the tube remains open) may experience the sensation of outward air flow which can

be annoying.

In 1982, the Minerals Management Service (MMS), U. S. Department of Interior, amended requirements of the Outer Continental Shelf (OCS) Hydrogen Sulfide Standard, MMS-OCS-1. "Safety Requirements for Drilling Operations in a Hydrogen Sulfide Environment, Outer Continental Shelf", Section 5.2, February 1976. MMS rescinded the requirement for personnel eardrum examinations and rescinded the prohibition against persons with perforated eardrums working in a hydrogen sulfide environment (refer to 47 Federal Register 28888-28890, July 1,1982).

The U. S. Occupational Safety and Health Administration may address this subject in future revision of its Respiratory Protection Standard

Concentration in Air

Percent Parts Per Grains Per

by Million 100 Std.

Volume By Volume Cubic Feet

0.000013 0.13'« 0.008""

15 20

100 300 500

0.63

0.94 1.26

3.15

6.30 18.90 31.49

0.001

0.0015 0.002

0.005

0.01 0.03 0.05

0.07 700 44.08

0.10+ 1000+ 62.98+

Milligrams Per Cubic

MeterW

0.18"«

14.41

21.61 28.83

72.07

144.14 432.40 720.49

1008.55 1440.98+

Typical Characteristics Regarding Hydrogen Sulfide Exposure^'___________

Obvious and unpleasant odor generally at 0.13 ppm and quite noticeable at 4.6 ppm. As the concentration increases, the sense of smell fatigues and the gas can no longer be detected by odor.'*'

Unpleasant odor. Possible eye irritation. ACGIH recommended Threshold Limit Value (TLV)® (eight-hour TWA).'⁷'

ACGIH STEL averaged over 15 minutes.'⁷'

Burning sensation in eyes and irritation of the respiratory tract after one hour or more exposure. OSHA ACC (refer to 29 Code of Federal Regulations Part 1910.1000, Subpart Z, Table Z-2).

Loss of sense of smell after about 15 or more minutes exposure. Exposure over one hour may lead to headache, dizziness, and /or staggering. Pulmonary edema reported following extended exposure to greater than 50 ppm/⁵' Exposure at 50 ppm or greater can cause serious eye irritation or damage.

Coughing, eye irritation, loss of sense of smell after 3 to 15 minutes. Altered respiration, pain in eyes, and drowsiness after 15 to 20 minutes, followed by throat irritation after one hour. Prolonged exposure results in a gradual increase in the severity of these symptoms.

Marked conjunctivitis and respiratory tract irritation.

Note: Concentration considered immediately dangerous to life or health (IDLH)"' (refer

to DHHS No. 85-114, NIOSH Pocket Guide to Chemical Hazards.'"»

Unconsciousness after short exposure, cessation of breathing if not treated quickly. Dizziness, loss of sense of reasoning and balance. Victims need prompt artificial ventilation and /or cardiopulmonary resuscitation (CPR) techniques.

Unconscious quickly. Breaming will stop and death will result if not rescued promptly. Artificial ventilation and/or cardiopulmonary resuscitation (CPR) is needed immediately.

Unconsciousness at once. Permanent brain damage or death may result. Rescue promptly and apply artificial ventilation

Table A-2—Summary of Occupational Exposure Values for Hydrogen Sulfide