Quebec H2S Regulations
Hydrogen Sulphide (also called “sour gas”, “sewer gas”)
This is not an official source of information. It has been assembled as a convenience to students for reference and further study. Some extracts from official sources such as Regulations are provided. These are not guaranteed to completely cover all the material available in the Regulations.
The following is © Gouvernement du Québec, 2009
c. S-2.1, r.19.01
Regulation Respecting Occupational Health and Safety
An Act respecting occupational health and safety
R.S.Q., c. S-2.1, s. 223. 1st par. subpar. (1), (3), (4), (7) to (16), (18) to (21.1), (41) and (42), 2nd par. and 3rd par
Definitions: In this regulation, the following words and expressions mean:
“air recirculation”: local exhaust ventilation by extraction, filtering of the air and redistribution of the filtered air in a work area;
”enclosed area“: any area that is completely or partially enclosed, especially a reservoir, a silo, a vat, a hopper, a chamber, a vault, a tank, a sewer including a ditch and a temporary manure storage ditch, a pipe, a chimney, an access shaft, a truck or freight car tank, which has the following inherent conditions:
(1) which is not designed for human occupation, nor intended to be, but may occasionally be occupied for the performance of work;
(2) access to which can only be had by a restricted entrance/exit;
(3) which can represent a risk for the health and safety of anyone who enters, owing to any one of the following factors:
(a) its design, construction or location, except for the entrance/exit provided for in subsection (2);
(b) its atmosphere or insufficiency of natural or mechanical ventilation;
(c) the materials or substances that it contains;
(d) or other related hazards;
“protective device”: set of devices which when used alone or with a protector on machinery, eliminates dangers or reduces risks for the health, safety and physical well-being of workers;
DIVISION X
STORAGE AND HANDLING OF DANGEROUS SUBSTANCES
§1. Interpretation and general provisions
70. Dangerous substances: In this section, “dangerous substance” designates a substance that is either a controlled product or a substance that appears on the list in Schedule II and that belongs to one of the following categories:
(1) compressed gases;
(2) flammable and combustible substances;
(3) combustive substances;
(4) toxic substances;
(5) corrosive substances;
(6) dangerously reactive substances.
71. Controlled product: In this section, “controlled product” means a product controlled within the meaning of the Regulation respecting information on controlled products (O.C. 445-89).
A dangerous substance that is both a controlled product and one appearing on the list in Schedule II, shall meet the requirements of this section applying to it, as regards each and every category to which it belongs both as a controlled product and a substance appearing on the list.
72. Safety precautions: The storage and handling of dangerous substances shall be so controlled as to prevent accidental spillage or lighting of these substances. The following precautions shall be taken:
(1) separate or isolate any dangerous substances which when mixed with other substances, may cause a fire or an explosion, or may discharge flammable or toxic gases;
(2) keep containers, piping and other apparatus in good working order;
(3) clean immediately but safely any dangerous substance spilled on floors or shelves;
(4) when pouring from one container to another, use a secure recipient taking into account the type of dangerous substance being poured;
(5) depending on the category in which the dangerous substance is classified, it shall comply with sections 77 to 99.
75. Emergency equipment: Emergency showers and eye wash fountains shall be put at the disposal of workers in the following circumstances:
(1) when a corrosive substance or other dangerous substance is likely to rapidly cause serious or irreversible damage to the skin or eyes of workers.
(2) when a toxic substance is likely to be rapidly absorbed by the skin or the eyes and cause them to have serious irritations.
In other cases, equipment for rinsing eyes and washing skin, such as showers, portable showers, eye wash fountains or any other type of plumbing shall be put at the disposal of workers, according to the nature of the dangers to which they are exposed. Such equipment shall be located near the work station of the exposed workers.
76. Shower facilities: Emergency showers and eye wash fountains referred to in the first paragraph of section 75 shall be clearly identified and easily accessible. In addition, they shall be located within the immediate vicinity of exposed workers and supplied with warm water.
Water from showers supplied by a drinking water network as well as water supplying portable showers shall be regularly changed to ensure its safety.
The warm water supply only applies to showers installed or modified starting on 2 August 2002.
83. Gaseous state flammable substances: Gaseous state flammable substances such as ammonia gas, hydrogen, acetylene and hydrogen sulfide shall never be stored with combustive substances or with oxidizing agents in a gaseous state such as chlorine, fluorine, nitrogen dioxide, nitrous oxides, nitrogen tetroxide, oxygen or compressed air.
DIVISION XXVI
WORKING IN AN ENCLOSED AREA
297. Definitions: For the purposes of this section, the following definitions shall apply:
“qualified person”: a person who, by reason of his knowledge, his training or his experience, is able to identify, assess and control the dangers relating to an enclosed area;
“hot work”: any work that requires the use of a flame or that can produce an ignition source.
298. Qualified workers: Only those workers who have the knowledge, training or experience required to do work in an enclosed area are qualified to perform work there.
299. Entry prohibited: Entry to an enclosed area is prohibited for any person who is not assigned to do work, to perform a task or to carry out a rescue there.
300. Gathering information before work: Before any work or task is carried out in an enclosed area, the following information shall be available, in writing, on the work premises:
(1) information on the specific dangers associated with the enclosed area and that concern:
(a) the prevailing internal atmosphere, namely the concentration of oxygen, inflammable gases and vapours, combustible or explosive dusts as well as the categories of contaminants likely to be present in this enclosed area or nearby;
(b) the fact that the natural or mechanical ventilation is insufficient;
(c) the materials that are present there and that can cause the worker to sink, to be buried or to drown, such as sand, grain or a liquid;
(d) the interior configuration;
(e) energies such as electricity, moving mechanical parts, heat stress, noise and hydraulic energy;
(f) ignition sources such as open flames, lighting, welding and cutting, static electricity or sparks;
(g) any other special circumstances such as the presence of rodents or insects;
(2) the prevention measures that should be taken to protect the health and to ensure the safety and well-being of workers, and in particular those concerning:
(a) safe methods and techniques for carrying out the work;
(b) appropriate and necessary work equipment to perform the work;
(c) the personal or collective protective means and equipment that the worker shall use when performing his work;
(d) the rescue procedures and equipment stipulated in section 309.
The information referred to in subparagraph 1 of the first paragraph shall be collected by a qualified person.
The precautionary measures referred to in subparagraph 2 of the first paragraph shall be drafted by a qualified person and implemented.
301. Information provided to workers prior to performing work: Information referred to in subparagraphs 1 and 2 of the first paragraph of section 300 shall be conveyed and explained to all workers before they enter an enclosed area ; this information shall be given by someone who is capable of adequately informing the workers on how to perform the work safely.
302. Ventilation: Except in cases where the safety of workers is ensured in compliance with subparagraph 3 of section 303, no worker may enter or be present in an enclosed area unless the latter is ventilated either by natural or mechanical means such that the following atmospheric conditions are maintained:
(1) the concentration of oxygen shall be greater than or equal to 19.5% and less than or equal to 23%;
(2) the concentration of inflammable gases or vapours shall be less than or equal to 10 %of the lower explosion limit;
(3) the concentration of one or more contaminants referred to under the sub- subparagraph of subparagraph 1 of the first paragraph of section 300 shall not exceed the standards provided in Schedule I for these contaminants;
If it proves impossible by ventilating the enclosed area to maintain an internal atmosphere in compliance with the standards provided under subparagraphs 1 and 3 of the first paragraph, a worker may only enter or be present in this area if he wears the respiratory protective equipment specified in section 45 and if the internal atmosphere of this enclosed area complies with subparagraph 2 of the first paragraph.
304. Hot work: Wherever hot work is performed in an enclosed area, a worker may only enter or be present therein if the following conditions are met:
(1) the conditions provided under sections 302 and 303;
(2) a continuous monitoring of the concentration of inflammable gases and vapours found therein is carried out by a direct reading instrument equipped with an alarm.
305. Special measures: Unless special precautionary measures are taken by the employer, no worker may enter or be present in an enclosed area when a qualified person has detected the presence of a contaminant, other than those referred to under section 300 and whose concentration requires the taking of such measures.
These measures include training devised by a qualified person and dealing with methods and techniques that shall be employed by the worker to carry out his work safely in this enclosed area. They can also provide, where necessary, for the use of equipment that is appropriate for this type of work as well as the other personal and collective protective means and equipment that the worker must use.
306. Method and frequency of readings: Readings of the oxygen concentration in the enclosed area as well as of inflammable gases and vapours and contaminants measurable by direct reading and likely to be present in the enclosed area or nearby shall be made:
(1) before workers enter the enclosed area and, subsequently, on a continuous or periodic basis, according to the evaluation of the danger made by a qualified person;
(2) if circumstances modify the internal atmosphere of the enclosed area and result in the evacuation of workers due to the fact that the quality of the air no longer complies with the standards set out in subparagraphs 1 to 3 of the first paragraph of section 302;
(3) if the workers leave the enclosed area and the work site, even momentarily, unless continuous monitoring is maintained.
The readings shall be taken in such a manner as to obtain an accuracy equivalent to that obtained following the methods described in section 44 or, when these measures cannot be applied, by following another recognized method.
307. Register of readings: The results of the readings made under section 306 shall be recorded by the employer in a register, on the work premises, identifying the enclosed area in question.
However, in the case where the readings are made using continuous reading instruments equipped with alarms that sound when the air quality does not meet the standards set out in subparagraphs 1 to 3 of the first paragraph of section 302, the readings shall only be recorded in the register if the alarm goes off.
Only those entries in the register that do not comply with the standards set out in subparagraphs 1 to 2 of the first paragraph of section 302 shall be kept for a period of at least 5 years.
308. Supervision: When a worker is present in an enclosed area, another person posted and having the skills and information to supervise the worker shall remain in visual contact, hearing contact or contact by any other means with the worker to initiate, if necessary, the rescue procedures quickly.
The person responsible for the supervision shall remain outside the enclosed area.
309. Rescue procedure: A rescue procedure making it possible to rapidly assist any worker performing work in an enclosed area shall be established and tested.
Such a procedure shall be implemented as soon as any situation so requires.
This procedure shall provide for the necessary rescue equipment. It may also make provision for a team of rescuers, an evacuation plan, alarm and communications devices, personal protective equipment, safety harnesses, lifelines, a first aid kit with emergency equipment as well as recovery equipment.
310. Unobstructed access: The personal or collective protective means or equipment used by workers shall not obstruct them when entering or leaving an enclosed area.
311. Precautions regarding free flow materials: No person may enter an enclosed area used to store free flow materials, when filling or emptying is taking place and when precautions have not been taken to prevent an accidental resumption of the operations.
312. Safety harness: When it is essential that workers enter an enclosed area where free flow materials are stored, each worker entering such an area shall wear a safety harness.
The safety harness shall be attached to a lifeline that is as short as possible and that is firmly attached outside the enclosed area.
SCHEDULE I
(a. 41, 42, 43, 66, 108 and 302)
PERMISSIBLE EXPOSURE VALUES FOR GASES, DUSTS, FUMES, VAPOURS OR MISTS IN THE WORK ENVIRONMENT
DEFINITIONS AND NOTES
The present schedule must be read in accordance with the following notations and definitions:
(1) CARCINOGENS: The designations under “carcinogen” in the Designation and remarks column refer to the following:
C1 : carcinogenic effect detected in humans
C2 : carcinogenic effect suspected in humans
C3 : carcinogenic effect detected in animals. Results of studies relating to the carcinogenocity of these substances in animals are not necessarily applicable to humans.
(2) CAS: Number given by the Chemical Abstracts Service, a division of the American Chemical Society, for the identification of a substance (see part 4).
(3) C: CEILING: The designation “C” in the STEV/Ceiling column refers to a concentration never be exceeded during any length of time whatsoever.
(4) EM: A substance to which exposure must be reduced to a minimum in accordance with section 42.
(5) EXCURSION LIMITS: These limits apply to substances which do not have a short-term exposure value. Provided the time-weighted average exposure value is not exceeded, excursions in exposure levels may exceed 3 times that value for a cumulative period not exceeding a total of 30 minutes during a workday. Notwithstanding the foregoing, none of those excursions in exposure levels may exceed 5 times the time-weighted average exposure value during any length of time whatsoever.
(6) mg/m3: milligram per cubic meter (milligram of substance per cubic meter of air).
(7) Pc : SKIN (percutaneous): The designation “Pc” in the Designation and remarks column refers to the potentially significant contribution to the overall exposure by the cutaneous route. Exposure is by contact with vapours or, of probable greater significance, by direct skin contact with the substance. The cutaneous route includes mucous membranes and the eyes.
(8) ppm: part per million (parts of gas or vapour per million parts of airborn contaminants per volume measured at 25°C and 101.3 kilopascals).
(9) Rd: Respirable dust.
(10) RESPIRABLE FIBRES (other than respirable asbestos fibres): Objects, other than respirable asbestos fibres, longer than 5 µm, having a diameter of less than 3 µm and a ratio of length to diameter of more than 3:1.
(11) RP: A substance which may not be recirculated in accordance with section 108.
(12) S: SENSITIZER: The designation “S” in the Designation and remarks column refers to a repeated exposure to a substance causing a sensitization, e.g. an organism reaction, in the form of an allergic response (immunologic) of the respiratory tree, the mucous, the conjunctivas or the skin.
(13) SIMPLE ASPHYXIANT: A physiologically inert gas which acts primarily by displacing airborne oxygen and that can cause a decrease in the percentage in volume of airborne oxygen below the 19.5% provided for in section 40 and required to maintain blood oxygen saturation.
(14) STEV: SHORT-TERM EXPOSURE VALUE: The 15-minute time-weighted average concentration for exposure to a chemical substance (in the form of gases, dusts, fumes, vapours or mists), present in the air in a worker’s respiratory zone which should not be exceeded at any time during a workday, even if the time-weighted average exposure value is not exceeded.
The average exposure for a 15-minute consecutive period may be include between the TWAEV and the STEV, insofar as such exposures are not repeated more than 4 times a day and have intervals between them of periods of at least 60 minutes.
(15) Td: Total dust.
(16) TWAEV: TIME-WEIGHTED AVERAGE EXPOSURE VALUE: The time-weighted average concentration for an 8-hour workday and a 40-hour workweek of a chemical substance (in the form of gases, dusts, fumes, vapours or mists) present in the air in a worker’s respiratory zone.
For any work period equal to or longer than 4 hours but less than 8 hours or a period in excess of 8 hours but less than or equal to 16 hours, an adjusted average exposure value (AAEV) must be established in accordance with the Guide to the adjustment of permissible exposure values for unusual work schedules, published by the Institut de recherche Robert-Sauvé en santé et en sécurité du travail, as it reads at the time it is applied. Under no circumstance may the AAEV be higher than the TWAEV.
NOTES DEFINITIONS:
Note 1: The standard corresponds to dust containing no asbestos and the percentage in crystalline silica is less than 1%.
Note 2a: Permissible asbestos exposure values in number of respirable fibres per cm3.
Note 2b: Permissible recirculation concentration of asbestos respirable dust: 0.1 mg/m3.
Note 3: Where the use of these products is permitted.
Note 4: Permissible exposure values in number of respirable fibres per cm3.
Substance: Hydrogen sulfide
CAS #: 7783-06-4
TWAEV: 10 ppm; 14 mg/m3
STEV/Ceiling: 15 ppm; 21 mg/m3