Space with limited entry and egress and not suitable for human inhabitants
A confined space is a space with limited entry and egress and not suitable for human inhabitants. Alternative names for a confined space are enclosed space and dangerous space.[1] An example is the interior of a storage tank, occasionally entered by maintenance workers but not intended for human occupancy. Hazards in a confined space often include harmful dust or gases, asphyxiation, submersion in liquids or free-flowing granular solids (for example, grain bins), electrocution, or entrapment.[2]
A confined space warning sign on process equipment.
Confined space accidents are of particular concern in occupational safety and health due to the hazards that they pose to the victim and subsequently to a rescue team.[2] Confined space training outlines the skills and protocols for safe entry to confined spaces, and includes precautions such as locking and tagging out connecting piping, testing of breathable air quality, forced ventilation, observation of workers in the space, and a predetermined rescue plan with appropriate safety harnesses and other rescue equipment standing by.
Description
Although the definition of a confined space varies between jurisdictions, it is generally recognized as a space that:
has limited or restricted means of entry or exit;
is large enough for a person to enter to perform tasks;
is not designed or configured for continuous occupancy;[3]
A utility tunnel, the inside of a boiler (only accessible when the boiler is off), the inside of a fluid storage tank, a septic tank that has contained sewage, and a small underground electrical vault are all examples of confined spaces. Ships and other vessels commonly have confined spaces due to the need for compartmentalized watertight construction.[4] The exact definition of a confined space varies depending on the type of industry. Until recently confined spaces on a construction site were defined differently than confined spaces in General Industry such as a paper mill. That changed due to a new confined space regulation for construction. Confined spaces that present special hazards to workers, including risks of toxic or asphyxiant gas accumulation, fires, falls, flooding, and entrapment may be classified as permit-required confined spaces depending on the nature and severity of the hazard.
Even normally habitable parts of a building such as corridors or offices may take on the characteristics of a confined space, during operations that alter normal ventilation and access. For example, a room may be wrapped in plastic sheeting for painting and any vapor emitted in the room may not be dispersed by blocked ventilation ducts.[2] But these areas would not be defined as confined spaces by OSHA.
In addition to the hazards posed by the design of the space, work activities can also pose serious safety hazards (heat, noise, vapors, etc.) that must be taken into account when identifying safety measures that must be taken.
Confined spaces are commonly encountered on ships, for examples spaces such as cofferdams, ballast tanks, fuel tanks and cargo tanks on oil tankers. Confined spaces with a hazardous atmosphere have resulted in numerous seafarer fatalities.[5] For this reason, confined (enclosed space) regulations for atmosphere monitoring are stated in the SOLAS Convention and also specified in industry Codes, such as the Code of safe working practices.[6]
Japan and South Korea
In Japan and South Korea, authorities have adopted definitions that highlight the oxygen-deficient nature of confined spaces. They define confined spaces as "oxygen deficient dangerous places" and operations in these spaces should be considered as having a permanent risk of oxygen depletion.[7]
United Kingdom
In the United Kingdom, a confined space is defined by the Health and Safety Executive as one which is enclosed or largely enclosed, with a reasonably foreseeable risk to workers from fire, explosion, loss of consciousness, asphyxiation and drowning.[8] The UK Confined Spaces Regulations 1997 sets out requirements for entry into confined spaces, including emergency arrangements.[9]
United States
In the United States, entry into permit-required confined spaces must comply with regulations promulgated by the Occupational Safety and Health Administration (OSHA). These regulations include developing a written program, issuing entry permits, assigning attendant(s), designating entrants, and ensuring a means of rescue.
According to the OSHA, a permit-required confined space (permit space) has the three characteristics listed above (which define a confined space) and one or more of the following:
Contains or has the potential to contain a hazardous atmosphere
Contains a material that has the potential for engulfing the entrant
Has an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section
Contains any other recognized serious safety or health hazards.
Atmospheric hazards
Fixed gas detector for monitoring atmosphere of
The most common hazard seen in confined spaces is that of atmospheric hazards. These affect air quality and present immediate hazards to health or life. Acceptable atmospheric conditions must be verified before entry, and must be monitored continuously while the space is occupied. The oxygen concentration, the presence of toxic gases, and flammable material are the conditions that must be monitored. Toxic gases that are commonly expected and monitored for include carbon dioxide, carbon monoxide, hydrocarbon vapours (including benzene, ammonia and hydrogen sulphide.[10]
According to OSHA, oxygen concentration is considered safe if it is between 19.5% and 23.5% of the total atmosphere. To protect against toxic gases, contaminants have permissible exposure limits (PELs), which are set by OSHA within the United States. Work also cannot continue if the concentration of a material reaches or exceeds 10% of its lower explosive limit.[11]
Other countries and authorities use a variety of reference systems for acceptable levels for toxic gas exposure. These include Threshold Limit Values (TLV), Short Term Exposure Limits (STEL) and Workplace Exposure Limits (WEL).[12] A Time Weighted Average (TWA) is defined as "where a person working in a zone for eight hours a day, five days a week, would not be expected to succumb to a TLV concentration if the average, after monitoring and calculation against the number of hours, was equal to or less than the current listed figure."[12]
Even if a tank or similar vessel initially is tested and found to contain breathable air, a hazard can develop during operations inside the tank if residues inside the tank can release toxic gas or vapor when disturbed or if accidentally ignited. Steel water tanks may have dangerously low oxygen concentration when the interior rusts.[13]
Entry certification
In many situations, certification of non-hazardous atmosphere by a trained or competent person is required before personnel may enter a confined space without the use of a respirator. In the United States Navy, that person is the designated shipboard gas-free engineer. In the maritime sector an NFPA Certified Marine Chemist is required to perform testing in all confined spaces that have contained a flammable, combustible or toxic substance. Certification in civilian settings can be performed by any employee who is trained and authorized by the employer. The Entry Supervisor, under OSHA regulations, is designated by the employer and ensures that the space is safe to enter and all hazards are controlled.
Guidance provided by OSHA stresses the importance of establishing procedures focused on preventing unauthorised access. It states that temporary confined space barriers need to be fitted "promptly" once entrance covers are removed for access. This prevents unauthorised access, accidental falls into the space and foreign objects entering in.[14]
In the United States, agricultural operations are exempted from regulations governing permit-required confined spaces (which is specific to general industry), but they are still required to identify and control confined space hazards.
Injuries and fatalities
Injuries and fatalities involving confined spaces are frequent and often involve successive fatalities when would-be rescuers succumb to the same problem as the initial victim. In the 1980s, approximately 60% of fatalities involve would-be rescuers and more than 30% of fatalities occur in a space that has been tested and found to be safe to enter. One example was in 2006 at the decommissioned Sullivan Mine in British Columbia, Canada when one initial victim and then three rescuers all died.
Accidents in confined spaces present unique challenges and are often catastrophic, such as the Xcel Energy Cabin Creek Fire in 2007.
In 1999, North West OHS[clarification needed] released a study of confined space fatalities based on reports from the Occupational Safety and Health Administration (OSHA), National Institute of Occupational Safety Health (NIOSH) and the Mines Safety and Health Administration (MSHA) with a breakdown of their causes. Researchers believe that the following numbers are only a fraction of the fatal confined space accidents that actually occurred as many locations are not initially identified as confined spaces, OSHA reports did not include non-hazardous confined space fatalities in their studies prior to 1982, NIOSH still do not include non-hazardous confined space fatalities in their studies and many American states do not note the presence of confined spaces in fatality reports submitted to OSHA.
Fire and Explosion (OSHA 1982a): 50 confined space incidents from 1974 to 1979 with 76 fatalities. The majority of incidents were caused by worker error or faulty equipment.
Lockout-tagout (OSHA 1982b): 83 confined space incidents from 1974 to 1980 with 83 fatalities. This category covers conveyor belts and machinery on the factory floor etc. that are not generally considered confined spaces, but which satisfy the criteria for a confined space.
Grain Handling (OSHA 1983): 105 confined space incidents from 1977 to 1981 with 126 fatalities.
Toxic and Asphyxiating Atmospheres (OSHA 1985): 122 confined space incidents from 1974 to 1982 with 173 fatalities.
Welding and Cutting (OSHA 1988): 217 incidents from 1974 to 1985 with 262 fatalities. OSHA reports of welding and cutting deaths do not record whether or not an incident has occurred in a confined space, it is estimated that 22% of the incidents were in a confined space.
Shipbuilding & Repair (OSHA 1990): 151 incidents from 1974 to 1984 with 176 fatalities. OSHA reports of shipbuilding deaths do not record whether or not an incident has occurred in a confined space, it is estimated that 36% of the incidents were in a confined space.
Mining (MSHA Report 1988): 38 confined space incidents from 1980 to 1986 with 44 fatalities.
According to data collected by the U.S. Department of Labor, Bureau of Labor Statistics, Census of Fatal Occupational Injuries program, fatal injuries in confined spaces fluctuated from a low of 81 in 1998 to a high of 100 in 2000 during the five-year period, averaging 92 fatalities per year.[15]
Where a system of entry permits is in place, a rescue plan is required, which includes a trained and equipped rescue team available within a reasonable response. It will list the personnel and equipment required to be at the worksite before entry is allowed. Special equipment such as tripod hoists, harnesses, and others may be required to extricate a worker from a toxic environment, without unduly endangering rescue personnel. In some industrial plants, Working at Height (WAH) and Confined Space (CS) rescue services are combined and delivered together.
See also
Heat stroke– Condition caused by excessive exposure to high temperatures.
Mine rescue– Rescue of persons trapped after mining accidents
↑ Trevor Kletz What Went Wrong:Case Histories of Process Plant Disasters, Fourth Edition, Elsevier, 1999 ISBN978-0-884 15-920-9 Chapter 11 "Entry into Vessels"
The Occupational Safety and Health Administration is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established the agency under the Occupational Safety and Health Act, which President Richard M. Nixon signed into law on December 29, 1970. OSHA's mission is to "assure safe and healthy working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education, and assistance." The agency is also charged with enforcing a variety of whistleblower statutes and regulations. OSHA's workplace safety inspections have been shown to reduce injury rates and injury costs without adverse effects on employment, sales, credit ratings, or firm survival.
Confined space rescue is a subset of technical rescue operations that involves the rescue and recovery of victims trapped in a confined space or in a place only accessible through confined spaces, such as underground vaults, storage silos, storage tanks, or sewers.
The Occupational Safety and Health Act of 1970 is a US labor law governing the federal law of occupational health and safety in the private sector and federal government in the United States. It was enacted by Congress in 1970 and was signed by President Richard Nixon on December 29, 1970. Its main goal is to ensure that employers provide employees with an environment free from recognized hazards, such as exposure to toxic chemicals, excessive noise levels, mechanical dangers, heat or cold stress, or unsanitary conditions. The Act created the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH).
Firefighting is a profession aimed at controlling and extinguishing fire. A person who engages in firefighting is known as a firefighter or fireman. Firefighters typically undergo a high degree of technical training. This involves structural firefighting and wildland firefighting. Specialized training includes aircraft firefighting, shipboard firefighting, aerial firefighting, maritime firefighting, and proximity firefighting.
The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment." Examples include smoke or other poisonous gases at sufficiently high concentrations. It is calculated using the LD50 or LC50. The Occupational Safety and Health Administration (OSHA) regulation defines the term as "an atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual's ability to escape from a dangerous atmosphere."
Process Safety Managementof Highly Hazardous Chemicals is a regulation promulgated by the U.S. Occupational Safety and Health Administration (OSHA). It defines and regulates a process safety management (PSM) program for plants using, storing, manufacturing, handling or carrying out on-site movement of hazardous materials above defined amount thresholds. Companies affected by the regulation usually build a compliant process safety management system and integrate it in their safety management system. Non-U.S. companies frequently choose on a voluntary basis to use the OSHA scheme in their business.
Dangerous goods (DG), are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials. An example for dangerous goods is hazardous waste which is waste that has substantial or potential threats to public health or the environment.
Lock out, tag out or lockout–tagout (LOTO) is a safety procedure used to ensure that dangerous equipment is properly shut off and not able to be started up again prior to the completion of maintenance or repair work. It requires that hazardous energy sources be "isolated and rendered inoperative" before work is started on the equipment in question. The isolated power sources are then locked and a tag is placed on the lock identifying the worker and reason the LOTO is placed on it. The worker then holds the key for the lock, ensuring that only they can remove the lock and start the equipment. This prevents accidental startup of equipment while it is in a hazardous state or while a worker is in direct contact with it.
The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) is an internationally agreed-upon standard managed by the United Nations that was set up to replace the assortment of hazardous material classification and labelling schemes previously used around the world. Core elements of the GHS include standardized hazard testing criteria, universal warning pictograms, and safety data sheets which provide users of dangerous goods relevant information with consistent organization. The system acts as a complement to the UN numbered system of regulated hazardous material transport. Implementation is managed through the UN Secretariat. Although adoption has taken time, as of 2017, the system has been enacted to significant extents in most major countries of the world. This includes the European Union, which has implemented the United Nations' GHS into EU law as the CLP Regulation, and United States Occupational Safety and Health Administration standards.
An asphyxiant gas, also known as a simple asphyxiant, is a nontoxic or minimally toxic gas which reduces or displaces the normal oxygen concentration in breathing air. Breathing of oxygen-depleted air can lead to death by asphyxiation (suffocation). Because asphyxiant gases are relatively inert and odorless, their presence in high concentration may not be noticed, except in the case of carbon dioxide (hypercapnia).
Right to know is a human right enshrined in law in several countries. UNESCO defines it as the right for people to "participate in an informed way in decisions that affect them, while also holding governments and others accountable". It pursues universal access to information as essential foundation of inclusive knowledge societies. It is often defined in the context of the right for people to know about their potential exposure to environmental conditions or substances that may cause illness or injury, but it can also refer more generally to freedom of information or informed consent.
A dust explosion is the rapid combustion of fine particles suspended in the air within an enclosed location. Dust explosions can occur where any dispersed powdered combustible material is present in high-enough concentrations in the atmosphere or other oxidizing gaseous medium, such as pure oxygen. In cases when fuel plays the role of a combustible material, the explosion is known as a fuel-air explosion.
Process safety is an interdisciplinary engineering domain focusing on the study, prevention, and management of large-scale fires, explosions and chemical accidents in process plants or other facilities dealing with hazardous materials, such as refineries and oil and gas production installations. Thus, process safety is generally concerned with the prevention of, control of, mitigation of and recovery from unintentional hazardous materials releases that can have a serious effect to people, plant and/or the environment.
Workplace health surveillance or occupational health surveillance (U.S.) is the ongoing systematic collection, analysis, and dissemination of exposure and health data on groups of workers. The Joint ILO/WHO Committee on Occupational Health at its 12th Session in 1995 defined an occupational health surveillance system as "a system which includes a functional capacity for data collection, analysis and dissemination linked to occupational health programmes".
A physical hazard is an agent, factor or circumstance that can cause harm with contact. They can be classified as type of occupational hazard or environmental hazard. Physical hazards include ergonomic hazards, radiation, heat and cold stress, vibration hazards, and noise hazards. Engineering controls are often used to mitigate physical hazards.
Manure management refers to capture, storage, treatment, and utilization of animal manures in an environmentally sustainable manner. It can be retained in various holding facilities. Animal manure can occur in a liquid, slurry, or solid form. It is utilized by distribution on fields in amounts that enrich soils without causing water pollution or unacceptably high levels of nutrient enrichment. Manure management is a component of nutrient management.
Inhalation is a major route of exposure that occurs when an individual breathes in polluted air which enters the respiratory tract. Identification of the pollutant uptake by the respiratory system can determine how the resulting exposure contributes to the dose. In this way, the mechanism of pollutant uptake by the respiratory system can be used to predict potential health impacts within the human population.
Grain entrapment, or grain engulfment, occurs when a person becomes submerged in grain and cannot get out without assistance. It most frequently occurs in grain bins and other storage facilities such as silos or grain elevators, or in grain transportation vehicles, but has also been known to occur around any large quantity of grain, even freestanding piles outdoors. Usually, unstable grain collapses suddenly, wholly or partially burying workers who may be within it. Entrapment occurs when victims are partially submerged but cannot remove themselves; engulfment occurs when they are completely buried within the grain. Engulfment has a very high fatality rate.
There are a number of occupational hazards of grain facilities. These hazards can be mitigated through diligence and following proper safety procedures. Grain facility occupation exposure is the quantifiable expression of workplace health and safety hazards to which a grain-handling facility employee is vulnerable in performing their assigned duties. Exposure represents the probability that a given hazard will have some level of effect of a receptor of interest. This page uses data and information about grain facility occupational exposure in the United States.
The 2021 Georgia poultry plant accident was an industrial disaster that occurred on January 28, 2021, in Gainesville, Georgia, United States. Six people were killed by asphyxiation and at least ten were injured when a liquid nitrogen leak occurred inside a poultry processing plant owned by Foundation Food Group.
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