The rule states that before an employee enters the space, the internal atmosphere must be tested with a calibrated direct-reading instrument for oxygen content, for flammable gases and vapors, and for potential toxic air contaminants.

Atmospheric Testing and the New OSHA Construction Confined Spaces Standard

Subpart AA of 29 CFR 1926 will help to prevent construction workers from being hurt or killed by eliminating and isolating hazards in confined spaces at construction sites.

In August 2015, OSHA's new standard for "construction work" in confined spaces became effective. This standard describes requirements for practices and procedures to protect employees engaged in construction activities at a work site with one or more confined spaces. OSHA believed this needed to be put into effect because, previously, the only requirement for confined spaces in construction was training. OSHA concluded this was inadequate because injuries and fatalities continued to occur.

How does the new rule differ from the rules that previously applied to construction work performed in confined spaces? The rule requires employers to determine what kinds of spaces their workers are in, what hazards could be there, how those hazards should be made safe, what training workers should receive, and how to rescue those workers if anything goes wrong.

Many workplaces contain areas that are considered "confined spaces" because, while they are not necessarily designed for people, they are large enough for workers to enter and perform certain jobs. Some examples of locations where confined spaces may occur include pits for elevators, escalators, pumps, valves, or other equipment; sewer, storm drain, electrical or other utility manholes; as well as boilers, tanks, storm drains, cesspools, silos, turbines, HVAC ducts, and chillers. A confined space like these may have poor natural ventilation that could contain or produce dangerous air contaminants.

According to data collected by the U.S. Department of Labor Bureau of Labor Statistics' Census of Fatal Occupational Injuries (CFOI) program, fatal injuries in confined spaces fluctuated from a low of 81 in 1998 to a high of 100 in 2000 and averaged 92 fatalities per year during the five-year period. Confined spaces can present physical and atmospheric hazards that can be avoided if they are recognized and addressed prior to entering these spaces to perform work. The new standard, Subpart AA of 29 CFR 1926, will help to prevent construction workers from being hurt or killed by eliminating and isolating hazards in confined spaces at construction sites. This is very similar to the way workers are already protected in other industries.

Understanding Atmospheric Hazards
Atmospheric hazards include things such as oxygen deficiencies, chemical vapors, and fumes that can interfere with the body's ability to transport and utilize oxygen or that have negative toxicological effects on the human body. Before entry into most confined spaces, a multi-gas monitor is commonly used to determine levels of oxygen, carbon monoxide, hydrogen sulfide, and the concentration of combustible gas. Other types of meters and sensors are available to detect the concentration of specific gases (chlorine, sulfur dioxide, etc.) if needed. The most common atmospheric hazards associated with confined spaces are oxygen depletion, toxic gas, and flammable gas.

Oxygen depletion or low levels of oxygen can be caused by the consumption of oxygen during open-flame operations such as welding, cutting, or brazing. In addition, low levels of oxygen can be present in manholes that are located near garbage dumps, landfills, and swampy areas where biological breakdown has caused the consumption of oxygen. Oxygen depletion also occurs when a gas displaces oxygen from a confined space. An example of this is nitrogen, which is commonly used to purge some types of tanks. If a person were to enter into the space before the nitrogen was properly vented from the tank, death could result very quickly.

Toxic gases can be present in a confined space because of toxic substances used as part of a production process, biological and chemical breakdown of a substance, or from maintenance activities (i.e., welding) being performed in the confined space. Common types of toxic substances encountered in confined spaces are hydrogen sulfide gas, carbon monoxide gas, and solvents.

Hydrogen sulfide, also known as "sewer gas," is a colorless gas with the odor of rotten eggs. Hydrogen sulfide causes a loss of one's sense of smell, causing people to mistakenly think that the gas has left the space. Excessive exposure has been linked to many confined space deaths. Hydrogen sulfide inhibits the exchange of oxygen on the cellular level and causes asphyxiation. Carbon monoxide is a deadly, odorless, colorless gas that is formed by burning carbon-based fuels (gasoline, propane, natural gas, wood, etc.). Carbon monoxide inhibits the body's ability to transport oxygen to all parts of the body. If inhaled at high concentrations, many solvents (such as kerosene, gasoline, paint strippers and degreasers) can cause central nervous system effects including dizziness, drowsiness, concentration, confusion, headaches, coma, and death. These solvents are not only toxic, but also potentially flammable. In order for an atmosphere to become flammable, it must have the proper mixture of fuel and oxygen. Some confined spaces my contain solvents, fuel oil, gasoline, kerosene, etc., which provide the fuel for combustion.

The General Requirements state that before an employee enters the space, the internal atmosphere must be tested with a calibrated direct-reading instrument for oxygen content, for flammable gases and vapors, and for potential toxic air contaminants, in that order. No hazardous atmosphere is permitted within the space whenever any employee is inside the space. The atmosphere within the space must be continuously monitored unless the entry employer can demonstrate that equipment for continuous monitoring is not commercially available or periodic monitoring is sufficient. If continuous monitoring is used, the employer must ensure that the monitoring equipment has an alarm that will notify all entrants if a specified atmospheric threshold is achieved or that an employee will check the monitor with sufficient frequency to ensure that entrants have adequate time to escape. If continuous monitoring is not used, periodic monitoring is required. Any employee who enters the space must be provided an opportunity to observe any required testing.

OSHA uses the term "permit-required confined space" (permit space) to describe a confined space that may have a hazardous atmosphere, engulfment hazard, or other serious hazard, such as exposed wiring that can interfere with a worker's ability to leave the space without assistance. Only workers who have been assigned and trained to work in a permit space may do so. Additionally, before workers can enter a permit space, the employer has to write a permit that specifies what safety measures must be taken and who is allowed to go in. If an employee is doing construction work, such as building a new structure or upgrading an old one, then employers must follow the construction confined space rule.

The Permit-Required Confined Space Program specified in the new standards requires that employers must implement the measures necessary to identify and evaluate the hazards of permit spaces before employees enter them and develop and implement the programs necessary for safe permit space entry operations. These include specifying acceptable entry conditions and providing each entrant or employee with the opportunity to observe any monitoring or testing of permit spaces atmospheric hazards. When testing for atmospheric hazards, a confined space is tested first for oxygen, then for combustible gases and vapors, and then for toxic gases and vapors. Employers will provide the testing and monitoring equipment needed at no cost to each employee, maintain that equipment properly, and ensure that each employee uses that equipment properly. The confined space will be continuously monitored for atmospheric hazards unless the employer can demonstrate that the equipment for continuously monitoring a hazard is not commercially available or that periodic monitoring is of sufficient frequency to ensure that the atmospheric hazard is being controlled at safe levels. If continuous monitoring is not used, periodic monitoring is required with sufficient frequency to ensure that acceptable entry conditions are being maintained during the course of entry operations.

Key Differences Between the Construction and General Industry Rules
There are five key differences between the general industry rule and the new construction rule and several areas where OSHA has clarified the existing requirements. There are more requirements regarding coordination of activities when there are multiple employers at the work site; evaluation of the work site and identification of confined and permit spaces; continuous atmospheric monitoring; continuous monitoring of engulfment hazards (flash flooding, for example); and allowances for the suspension of a permit, instead of cancellation, under certain circumstances.

In addition, OSHA has added provisions to the new rule that clarify existing requirements in the general industry standard. These include requiring employers to prevent workers' exposure to physical hazards through elimination of the hazard or isolation methods (such as lockout/tagout) when not using a complete permit system. Employers who are relying on local emergency services are required to arrange for advance notice from responders if they will be unable to arrive for a period of time. Employers also must provide training in a language and vocabulary that the worker understands. Finally, several terms have been added to the definitions for the construction rule, such as "entry employer" and "entry rescue."

The new OSHA standard for "construction work" in confined spaces became effective in August 2015. This standard describes requirements for practices and procedures to protect employees engaged in construction activities at a work site with one or more confined spaces. The rule states that before an employee enters the space, the internal atmosphere must be tested with a calibrated direct-reading instrument for oxygen content, for flammable gases and vapors, and for potential toxic air contaminants. Where this standard applies and there is a confined space hazard provision in another applicable OSHA standard, the employer must comply with both requirements.

An employer whose workers are engaged in both construction and general industry work in confined spaces will meet OSHA requirements if that employer meets the requirements of 29 CFR 1926 Subpart AA - Confined Spaces in Construction. The new standard does state a few exceptions and does not apply to construction work regulated by other standards, such as excavations, underground construction, caissons, cofferdams, compressed air, and diving.

References
Part 1926, Safety and Health Regulations for Construction
1. http://www.ecfr.gov/cgi-bin/text-idx?SID=87380ef8ec1bc21610ac395d2863d65f&mc=true&node=sp29.8.1926.aa&rgn=div6
2. http://www.sc.edu/ehs/modules/Confined%20Space/05_flammable.htm
3. http://www.cdc.gov/niosh/topics/confinedspace/default.html
4. https://www.osha.gov/SLTC/confinedspaces/index.html
5. https://www.osha.gov/confinedspaces/faq.html

This article originally appeared in the December 2015 issue of Occupational Health & Safety.

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