INTRODUCTION

The purpose of this booklet is to alertemployers and workers to the dangers involvedin working with H2S and to provide guidancefor controlling these dangers.

Hydrogen sulphide gas is one of the mostdeadly occupational hazards in Alberta. It goesby many names: H2S, sour gas, sewer gas,stink damp, and sulfuretted hydrogen.

Workers in the oil and gas industry must beaware of its deadly properties. Sewermaintenance crews, blasters, and miners havelearned to respect this gas.

Employers must ensure that workers whomay be exposed to H2S gas are able torecognize its lethal effects. Procedures must bein place to ensurethat victims whoare overcome arerescued and givenfirst aid.

BE ALERT! TAKE EVERY PRECAUTION

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SOURCES OF H2S

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PROPERTIES OF H2S

COLOUR Colourless

ODOUR Very offensive,commonly referred toas odour of rotteneggs at lowconcentration1.188 at 25°C

VAPOUR DENSITY 1.189 (Air = 1.0) H2S in its pure formis heavier than air

EXPLOSIVE LIMITS 4.3 to 46.0 percent byvolume in air

AUTO IGNITIONTEMPERATURE 260°C

FLAMMABILITY Forms explosivemixture with air oroxygen

WATER SOLUBILITY 2.9 percent (2.9 g/100ml water at 20°C)

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EFFECTS OF H2S

1 ppm Can be smelled.

10 ppm Alberta OccupationalExposure Limit(OEL). Allowable for8 hours of exposure.

15 ppm Alberta Ceiling OEL.An unprotectedworker may not beexposed above thisconcentration.

20-50 ppm Severe eye irritation.Nose, throat and lungirritation.Loss of appetite.

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100-200 ppm Severe nose, throat andlung irritation.Ability to smell odourcompletely disappears(150 ppm)

500 ppm Severe lung irritation.Headaches, dizziness,staggering, collapse.

500-1000 ppm Respiratory paralysis.Irregular heart beat,collapse or death.

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ppm = Parts of gas per million parts of air by volume. 1% = 10,000 ppm

DETECTION OF H2S

Hydrogen Sulphide in low concentrations iseasily recognizable by its characteristic foulodour similar to rotten eggs. However,continued exposure or exposure toconcentrations over 100 ppm will temporarilyeliminate one’s ability to smell the gas. Theeffect usually misleads the worker into thinkingthe danger has passed; often with tragic results.

The acute effects of H2S on the body aretwofold. H2S acts as an irritant to eyes, nose,throat and lungs, and it acts as an internalpoison causing unconsciousness by paralysis ofthe respiratory system.

WHEN TESTING FOR THE PRESENCE OF H2SBE PREPARED FOR LETHAL CONCENTRATIONS

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You can detect the presence of H2S at lessthan 1 ppm by its odour. Unfortunately, it maybe the last thing you ever smell. If theconcentration of the gas is above the 100 ppmrange the sense of smell is quickly deadened,giving a false sense of security that the dangerhas passed.

WARNINGYou cannot rely on your nose to tell you

how much H2S is present!Wear your respiratory protection.

To determine the presence of H2S in yourwork area, one of the following means ofdetection should be used:

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Continuous MonitorsIn larger plants, a system is used where

potentially hazardous areas are sampled bystrategically located sensors. An alarm systemis activated by any sensor and will givewarning when the H2S concentration risesabove preset limits for the area sampled.

Personal MonitorsBattery worn H2S monitors can be carried or

worn by individual workers to indicate theconcentration of H2S to which they are beingexposed.

Portable MonitorsFamiliarize yourself with the detection

equipment at your work site. Learn its properoperation. Maintain and operate it according tothe manufacturer’s specifications.YOUR LIFE MAY DEPEND ON IT!

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PROTECTION

When you are in an area where H2S is apotential hazard, you must wear approvedpersonal protective and respiratory protectiveequipment required by the AlbertaOccupational Health and Safety (OHS) Code,Part 18.

The employer must:

n select respiratory protective equipment inaccordance with the CSA Standard Z94.4-02,Selection, Use and Care of Respirators

n prepare a written code of practice regardingthe selection, maintenance and use ofrespiratory protective equipment

n ensure that all equipment used is approvedby NIOSH or another organization approvedby a Director of Occupational Hygiene

n ensure that respiratory protective equipmentis stored and maintained properly

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n fit test equipment in accordance with theCSA Standard Z94.4-02, Selection, Use andCare of Respirators

n ensure that workers are clean shaven wherethe face piece of the respirator seals to theskin of the face

n if conditions at the work site may becomeimmediately dangerous to life or health,workers must wear positive pressure self-contained breathing apparatus that meets therequirements in section 251 of the OHSCode.

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TWO COMMON TYPESOF RESPIRATORY

PROTECTION FOR H2S

Self-Contained Breathing Apparatus

This type of apparatus supplies compressed airfrom a cylinder worn on the back to a fullfacepiece. This apparatus must be of the typethat maintains positive pressure in thefacepiece.

The cylinder must be rated to supply air forat least 30 minutes.

Heavy physical work will consume availableair more quickly.

All self-contained breathingapparatus must be equippedwith an alarm to warn whenthe air pressure is low.

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Self-contained breathing apparatus

Supplied Air Breathing ApparatusThis apparatus supplies respirable air fromcylinders, or a compressor in a remote location,via a hose to a full facepiece. This apparatusmust be of a type that maintains positivepressure in the facepiece.

An emergency escape bottle must be wornwith this type of equipment in case of aninterruption of supplied air.

The emergency escape bottle is for escapepurposes only and must never be used alone tocarry out work in an H2S environment.

NOTE: To prevent inwardleaks of contaminated air,the worker must be cleanshaven where the facepiececontacts the skin of the face.

Supplied air breathing apparatus

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SSPPEECCIIAALL RREEQQUUIIRREEMMEENNTTSS

The first concern in any area contaminated withH2S is the protection of the life and health ofthe worker. There are certain jobs which causeH2S to be released into the air. When workinginside vessels, tanks, etc., workers must beprotected by respiratory protective equipmentand practice safe work procedures.

A number of precautions must be observed ifprotection is to be adequate for the worker:

n The employer must take steps to eliminate orcontrol the hazard from H2S, if this isreasonably practicable.

n If the work involves entry into a confinedspace, the requirements in Part 5 of the OHSCode must be complied with.

n Since H2S is a flammable gas, requirementsin Part 10 of the OHS Code apply.

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n If the work shift is more than 8 hours, theOEL for H2S must be adjusted, using theformula in section 18, Part 4 of the OHSCode.

n A written code of practice is required forwork sites where there is more than 10 kg ofH2S present as a pure substance, or there is amixture in which there is more than 10 kg ofH2S and the concentration of H2S is morethan 0.1 percent by weight.

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RESCUE & FIRST AID

ALWAYS PUT ON RESPIRATORY PROTECTIONBEFORE ATTEMPTING ANY RESCUE.

YOU COULD BECOME A VICTIM!

It is VITALLY IMPORTANT that everyoneworking around or near H2S has a goodworking knowledge or artificial respiration(rescue breathing):

n Training in C.P.R. (cardiopulmonaryresuscitation) would be a stronglyrecommended addition to a worker’sknowledge and skills in first aid.

n Part 11 of the OHS Code requires thatpersonnel be trained in first aid.

n It is important when workers use respiratoryprotective equipment for rescue that they areaware of the limitations of each type ofequipment.

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n Regular practice and training in rescue arenecessary to provide appropriate rescuecapability at the work site.

n Part 7 of the OHS Code providesrequirements for emergency preparednessand response.

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EMPLOYER RESPONSIBILITY

The employer has key responsibilities for injuryand incident prevention. It is most important to:

n Know and inform workers about the companypolicy on H2S.

n Know safe work procedures and include themin instructions when teaching job methods.

n Identify unsafe conditions and actions.

n Take IMMEDIATE and appropriate actionwhen H2S is suspected or detected.

n Know the workers under your supervisionwell enough to notice any changes in attitudeor physical/mental condition that may be dueto H2S exposure.

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n Be aware of training required for H2Senvironments where work may be done thatcould endanger a worker. A worker musteither be competent or directly supervised bya competent worker.

n Conduct sessions to inform workers of the“Code of Practice” and “Safe WorkProcedures” that are used on your work siteprior to commencement of work.

n Ensure that safety meetings are held forworkers. These should be used forinstruction, review or discussion of unsafeconditions or actions which have beenobserved. Workers should be encouraged totake an active part in these meetings. Theirconstructive suggestions help keep safe workpractices up to date.

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n Ensure workers have appropriate first aidtraining.

n Ensure that personal protective equipmentused by the worker does not endanger theirhealth and safety.

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WORKER RESPONSIBILITY

The worker, as well as the employer, hasresponsibilities under the Occupational Healthand Safety Act.

n When workers must wear personal protectiveequipment, they must use the appropriateequipment and they must not use personalprotective equipment that is not in a conditionto perform the function for which it wasdesigned.

n Workers with equipment under their controlthat does not comply with the OHS Codemust remove that equipment from service.

n Workers must be aware of the “Code ofPractice” developed for jobs involvingconfined space entry and must not enter orremain in a confined space if controlmeasures are not in place.

n Participate in training programs provided bythe employer.

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