Examples Of Confined Spaces

Navigating the hazards and complexities of confined spaces is essential to maintaining a safe work environment. This article delves into the various types of confined spaces, from tanks and silos to tunnels and attics, while shedding light on associated hazards and career paths involving these unique areas.

We also explore crucial safety precautions outlined by organizations such as OSHA (Occupational Safety and Health Administration) to help mitigate risks for those who enter these challenging environments.

Key Takeaways

  • Confined or partially enclosed spaces pose risks to workers due to their design, construction, location, or contents. Examples include tanks, industrial equipment and fixtures, pits, sewers and underground installations, tunnels, crawl spaces, and attics.
  • Hazards associated with confined spaces include oxygen deficiency/enrichment, airborne combustible dust, and flammable gas/vapor/mist. Safety measures like atmospheric testing before entry/performing any tasks inside confined spaces using gas detectors must be strictly followed to mitigate these risks.
  • Proper training on confined space entry and rescue procedures is essential for workers entering such hazardous environments. Mechanical ventilation should be used whenever possible to improve air quality in tunnels and crawl spaces, while following OSHA regulations can help prevent workplace accidents related to confined spaces.
This hero image features a worker wearing safety gear and performing a task inside a confined space, such as a tank or silo. The image focuses on the worker's concentration and attention to detail while highlighting the safety precautions being followed. The background can show elements of the confined space environment, such as pipes or industrial machinery, to convey the unique challenges of working in such spaces.

What Is A Confined Space?

A confined space is a place that is enclosed or partially enclosed, has limited access and egress, and can pose a risk to the health and safety of workers due to its design, construction, location, or contents.

Definition And Characteristics

A confined space, as defined by the Occupational Safety and Health Administration (OSHA), refers to an enclosed area with limited access or egress, not designed for continuous human occupancy, and has the potential for hazardous atmospheres. These spaces can be found in various industries, such as construction, agriculture, and manufacturing.

Some common characteristics of confined spaces include tight entry points, poor natural ventilation leading to oxygen deficiency or toxic gas build-up, lack of lighting, and restricted movement within the space. For example, workers may be required to crawl through small tunnels or work carefully within a fuel tank surrounded by flammable vapors.

Hazards Associated With Confined Spaces

Working in confined spaces can be dangerous due to hazards such as oxygen deficiency or enrichment, airborne combustible dust, and flammable gas, vapor, or mist.

Oxygen Deficiency Or Enrichment

Oxygen deficiency or enrichment poses significant risks to workers in confined spaces. A safe oxygen level ranges from 19.5% to 23.5%. Levels below the minimum can lead to asphyxiation, unconsciousness, and even death due to a lack of oxygen in the air.

One real-life example occurred when an employee entered a confined space with inadequately monitored oxygen levels; tragically, they lost consciousness and died due to asphyxiation caused by depleted oxygen content.

To prevent such occurrences, it is critical for employers and employees alike to regularly monitor atmospheric conditions within confined spaces using gas detectors or other appropriate methods before entry or performing any tasks inside these areas.

Airborne Combustible Dust

Airborne combustible dust is a hazardous element often encountered in confined spaces, posing significant risks to workers and equipment. This fine particulate matter can be generated from various sources such as wood, coal, grain, metal shavings, or powdered chemicals.

To help mitigate these risks within confined spaces, employers and employees alike need to implement proper safety measures, such as implementing controls for dust accumulation and ensuring adequate ventilation systems are in place.

Additionally, continuously monitoring air quality with specialized devices can detect dangerous increases in airborne combustible dust levels before they become a threat. Workers must also receive appropriate training on recognizing and managing this hazard effectively while using personal protective equipment (PPE) designated for use in dusty environments.

Flammable Gas, Vapor, Or Mist

Flammable gases, vapors, or mists are among confined spaces’ most significant hazards. These substances can ignite and explode when they come into contact with a spark or source of heat. Examples include methane, propane, gasoline fumes, and solvents like acetone.

To prevent an explosion, all ignition sources must be controlled before entering a confined space where flammable substances may be present. This includes electrical devices that could generate a spark or hot work, such as welding that could produce heat.

Types Of Confined Spaces

There are various confined spaces, including tanks, industrial equipment and fixtures, pits, sewers and underground installations, tunnels, crawl spaces, and attics.

Tanks, Bins, And Silos

Tanks, bins, and silos are common confined spaces in various workplaces. When determining whether these confined spaces are hazardous, risk assessment is crucial. Hazards associated with tanks, bins, and silos can include poor air quality due to oxygen deficiency or enrichment, airborne combustible dust, flammable gas, vapor, or mist.

Identifying these hazards is critical because the potential consequences can be severe. Due to the small margin for error in these spaces and the limited movement of people or equipment, a lack of communication between workers and emergency responders can also be a safety hazard.

Air quality testing should be conducted before entering the space to ensure safety. Special precautions such as eliminating hazards or substituting materials may be necessary, in addition to mechanical ventilation, administrative controls, and personal protective equipment. Hot work should only be performed when all flammable gases have been removed, and ventilation is used continuously to prevent fire hazards.

Industrial Equipment And Fixtures

Industrial equipment and fixtures can also be considered confined spaces. These include:

  • Large furnaces and boilers with restricted means of entry or exit
  • Smokestacks and chimneys
  • Incinerators
  • Mixing vats and tanks
  • Boilers with limited access points
  • Air handlers and associated ductwork
  • Conveyor tunnels for materials handling
  • Trash compactors, balers, and crushers

According to the Canadian Centre for Occupational Health and Safety (CCOHS), these confined spaces have the same potential hazards as others. Conducting a hazard assessment before entering an industrial equipment or fixture confined space is important, as implementing safety procedures such as lockout/tagout, atmospheric testing, personal protective equipment, and having a rescue plan in an emergency.

Falling debris, chemical exposure, hot surfaces, or steam burns from furnaces/boilers are some examples of the dangers that can be present in these types of confined spaces.


Pits are classified as confined spaces that can pose significant hazards for workers. Here are some examples of pits that are considered confined spaces:

  • Open-top pits: These may be found in construction sites or mining operations and can quickly accumulate toxic gases, hazardous vapors, or flammable materials.
  • Elevator shafts require special precautions due to the risk of falls, electric shock, and other hazards associated with working at height.
  • Dock levelers: Workers may need to enter these to repair or maintain the equipment below.
  • Escalator pits: These provide access to the machinery that drives the escalators but can be difficult to navigate due to their small size.
  • Manholes: These are commonly found in utility networks such as sewer systems, electrical grids, and telecommunications networks. They often contain high levels of toxic gases and other hazards.

To ensure worker safety when working in pits and other confined spaces, it is essential to conduct a hazard assessment and control program. Proper training and using personal protective equipment (PPE) can also help prevent accidents and reduce injuries on the job.

Sewers, Vaults, And Underground Installations

Sewers, vaults, and underground installations are examples of confined spaces. Workers can encounter poor air quality in these confined spaces due to a lack of ventilation and toxic gases or chemicals. A thorough risk assessment should identify potential hazards to ensure safety when entering these confined spaces.

Air quality testing is crucial before entering a confined space, especially in sewers and underground installations where harmful gases or fumes may build up. Continuous monitoring may also be necessary since the air quality inside the confined space can change rapidly.

Hazard control programs should be implemented based on identified risks associated with these confined spaces. Special precautions are also needed for working in sewers and underground installations to protect workers from biological hazards like bacteria and viruses that could cause infection or illness.

Tunnels And Crawl Spaces

Tunnels and crawl spaces are confined spaces commonly found in construction, maintenance, and repair work. These areas are usually narrow, dark, and poorly ventilated, making them risky to enter without proper precautions. Here are some facts to remember when working in tunnels and crawl spaces:

  • Tunnels can be natural or man-made, with different hazards associated with each type.
  • Crawl spaces are typically found under buildings with limited headroom and access points.
  • Workers may encounter hazardous materials such as asbestos or lead in older tunnels or crawl spaces.
  • Poor ventilation in these areas often leads to decreased oxygen levels or an accumulation of toxic gases.
  • To ensure worker safety, confined space safety procedures must be followed when entering tunnels or crawl spaces.
  • Proper training on confined space entry and rescue procedures is essential for any worker entering these areas.
  • Mechanical ventilation should be used whenever possible to improve air quality in tunnels and crawl spaces.

Remember that the hazards associated with working in tunnels and crawl spaces can be severe, so it’s crucial to approach these areas cautiously. By following proper safety protocols and using mechanical ventilation, workers can greatly reduce their risk of injury or illness when working in these confined spaces.


Attics can be categorized as a type of confined space. Workers need to climb ladders and squeeze through an opening to access it. Attics may contain insufficient oxygen, which can lead to asphyxiation. Toxic gases, airborne dust, and chemical exposures are potential hazards in attics.

For safe entry into an attic, workers must evaluate the situation before entering, identify potential hazards such as poor air quality or toxic gases, continuously test and monitor the atmosphere for changes, wear personal protective equipment, and collaborate with another worker who can call for help.

OSHA Definitions And Requirements

OSHA has specific standards and requirements for working in confined spaces, including training and rescue plans.

Permit-required Confined Spaces

Permit-required confined spaces contain hazardous materials or conditions that could endanger workers. These spaces require specific safety measures and a permit for entry.

OSHA has established specific standards and requirements for working in confined spaces to ensure worker safety. Employers must have a written program outlining procedures for identifying hazards and controlling access to the space through an entry permit system.

Training is essential for all employees working in or around these spaces to identify potential hazards and effectively communicate with their colleagues during emergencies. It is also crucial to have a rescue plan outlining procedures and equipment needed in case of emergency.

Non-permit Required Confined Spaces

Non-permit-required confined spaces do not contain hazardous materials or conditions that may endanger workers. Examples of these confined spaces may include small storage areas or crawl spaces where entry and exit points are easy to access, and there is no risk of asphyxiation or exposure to harmful substances.

Employers must ensure that their employees receive adequate training on the hazards of entering any confined space, including non-permit required ones. In addition, employers should have procedures in place for determining whether a space meets the requirements for being considered non-hazardous before allowing workers to enter.

Safety Precautions For Working In Confined Spaces

Assess the risks before entering a confined space, use a confined space safety checklist, and have a rescue plan in place.

Risk Assessment

A risk assessment and control program should be implemented to effectively control risks associated with working in a confined space. Here are some important things to consider during the risk assessment process:

  • Identify all potential hazards in the confined space, including oxygen deficiency or enrichment, flammable gases or vapors, combustible dust, and more.
  • Evaluate the likelihood and severity of each hazard.
  • Determine appropriate measures to eliminate, control, or minimize each hazard. Traditional methods in regular worksites can be effective in a confined space, such as elimination, substitution, mechanical ventilation, administrative controls, and personal protective equipment.
  • Identify emergency procedures and equipment, such as rescue plans and retrieval systems.
  • Consider the qualifications of workers entering the confined space and ensure they have received proper training for working safely in that environment.

Regular risk assessments throughout an ongoing project are essential as atmospheric conditions can change, which might increase the potential hazards.

Confined Space Safety Checklist

A confined space safety checklist is essential for ensuring workers’ safety before entering a confined space. Here are the key items to include in a confined space safety checklist:

  1. Evaluate the area: Assess the confined space for potential hazards, including atmospheric conditions, electrical, mechanical, and other physical hazards.
  2. Identify potential hazards: Determine if any materials or equipment present could pose significant harm to workers once they enter the confined space.
  3. Test and monitor atmosphere: Perform air quality testing and ongoing monitoring of the atmosphere in the confined space before and during work to maintain appropriate oxygen levels.
  4. Proper ventilation: Ensure adequate ventilation is available in fans or ducting systems to bring fresh air into the confined space.
  5. Personal Protective Equipment (PPE): Workers should wear appropriate PPE such as respiratory protection, eye protection, gloves, hard hats, and steel-toed boots.
  6. Have a rescue plan in place: Create a rescue plan that details how to quickly remove an injured or ill worker from a confined area.

These essential elements can help provide guidance and promote safety when working in confined spaces. Employers should regularly reinforce these guidelines through training sessions and periodic audits of restrictive areas to ensure compliance with OSHA standards and other applicable regulations.

Rescue Plans

Rescue plans are essential for working in confined spaces with severe hazards. To ensure the safety of workers, employers should establish a rescue plan that includes the following:

  • Identification of the Entrants: Employers need to identify workers tasked with entering confined spaces and assess their training, skills, and experience.
  • Training and Equipment: Employers must provide training on using personal protective equipment (PPE) and emergency equipment such as first-aid kits, respirators, and communication devices.
  • Rescue Procedures: Employers must establish a procedure for rescuing entrants in an emergency. The procedure should include how to call for help and what actions rescuers must take.
  • Practice Drills: Workers should practice rescue procedures at least once every 12 months to maintain their skills and prepare them for emergencies.
  • Retraining: Employers must retrain workers if workplace changes or job duties affect their ability to carry out safe work practices.

By implementing a comprehensive rescue plan, employers can minimize risks associated with confined space work activities while ensuring all necessary precautions have been taken in case of unexpected events.

This hero image depicts a team of professionals standing in front of a confined space entry point, symbolizing the importance of safety and certification. The workers can be shown wearing safety gear and holding tools specific to confined space work. The image aims to convey a sense of responsibility and expertise, emphasizing the role of certified professionals in ensuring safety in confined spaces.

Careers Involving Confined Spaces

Construction workers, welders, search and rescue officers, pipeline inspectors, tank inspectors, electricians, vacuum truck operators, and site supervisors are just a few examples of professionals who may work in confined spaces as part of their job duties.

Construction Worker

Construction workers often work in confined spaces when constructing buildings or roads. These spaces can include crawl spaces, utility tunnels, and attic spaces requiring crawling or climbing ladders. Working in such tight quarters can be dangerous if proper precautions are not taken.

To keep construction workers safe working in confined spaces, they must evaluate their surroundings and identify potential hazards. They should continuously test and monitor the air quality while wearing personal protective equipment since they could collaborate with a second person outside the space to call for help if necessary.


Welders are highly skilled professionals who join metal components together using heat. They are critical in various industries, including manufacturing, construction, and transportation. However, welders often work in confined spaces such as pipelines, vessels, and boilers which present potential hazards like poor ventilation and toxic gases that can cause accidents or injuries.

Evaluating the situation before starting work is essential to prevent untoward incidents during welding processes in confined spaces. Monitoring the atmosphere for dangerous gases and wearing personal protective equipment are also crucial for a safe working environment.

Search And Rescue Officer

Search and rescue officers are highly trained professionals responsible for responding to emergencies and saving lives in confined spaces. They may be called upon to enter a dangerous environment, such as underground tunnels, wells, tanks, or pipelines, to retrieve individuals trapped inside.

According to [IMPORTANT FACTS], the national average salary for a search and rescue officer is $51,222 per year. In addition to their rigorous training in confined space rescues, many officers also hold medical response or firefighting certifications.

Pipeline Inspector

Pipeline inspectors play a crucial role in ensuring the safety of pipelines, especially those that transport hazardous materials. Their job involves supervising pipelines’ construction and operation to ensure they meet safety standards.

As part of their duties, pipeline inspectors may have to enter confined spaces, such as tanks or tunnels, to perform inspections. Hazards in these areas can include poor air quality, toxic gases, asphyxiants, and chemical exposures. Pipeline inspectors must be trained to identify and evaluate potential hazards in confined spaces before entering.

Pipeline inspectors may work on oil fields, refineries, or transportation systems with an average annual salary of $51,265 per year, according to recent studies by PayScale.com. The importance of pipeline integrity cannot be overstated, with significant environmental and public safety implications should something go awry.

Tank Inspector

Tank inspectors specialize in assessing the safety and operation of tanks, including those that contain hazardous chemicals. These experts are crucial in ensuring compliance with OSHA regulations and safety standards.

They use specialized equipment to measure various parameters such as temperature, pressure, and chemical composition inside tanks. Tank inspectors may work with waste treatment tanks or inspect fuel tanks for airplanes or boats.

As part of their job duties, tank inspectors may need to enter confined spaces to conduct inspections. They must wear personal protective equipment such as gloves and respirators to ensure their safety while conducting inspections in confined spaces like tanks.


Electricians are essential workers when it comes to maintaining and repairing electrical systems, often in confined spaces. These spaces can include utility tunnels, crawl spaces, or attic spaces requiring navigating through tight areas with live electric currents. As such, these professionals must be aware of hazards such as poor ventilation or toxic gases in the atmosphere.

According to national averages, electricians earn an annual salary of $59,162 annually in the US. Alongside their technical knowledge of electrical systems installation and repair, they also undergo training on occupational safety regulations governing work environments involving confined spaces.

Vacuum Truck Operator

A vacuum truck operator is one of the many careers that involve working in confined spaces. These operators are responsible for driving specialized trucks equipped with a suctioning function to extract liquid materials like oil, gas, or sewage waste.

Sometimes, these operators may need to enter confined spaces to access material or clean their tanks. To ensure proper safety procedures, vacuum truck operators must undergo rigorous training on operating equipment and working in confined spaces safely.

Site Supervisor

Site supervisors are crucial in overseeing technical sites involving confined spaces, such as those found in the construction, manufacturing, and transportation industries. They are responsible for ensuring that projects meet all OSHA regulations and standards, including those related to confined spaces. The national average salary for a site supervisor is $70,383 per year (according to Glassdoor).

This position requires excellent communication skills as they must work on-site with contractors and other team members. In addition to their supervisory responsibilities, site supervisors should have extensive knowledge of confined spaces since they are accountable for the safety of all personnel involved in projects under their supervision.

Conducting regular risk assessments before entering any potentially hazardous area, implementing control programs designed specifically for each workspace’s needs, or using mobile applications like SafetyCulture’s iAuditor app can help reduce any risks associated with working in confined spaces.


In conclusion, it is essential for workers and employers to understand what constitutes a confined space and its associated hazards. From tanks to tunnels, there are many examples of confined spaces that require proper safety precautions, such as risk assessments, safety checklists, and rescue plans.

Careers in fields such as construction, welding, and search and rescue often involve working in confined spaces. Following OSHA standards and regulations is important to ensure worker safety when working in these environments.

Frequently Asked Questions:

1. What are some examples of confined spaces?

Confined spaces can include areas like tanks, silos, sewers, crawlspaces, and other enclosed or partially enclosed areas with limited entry/exit points and pose a risk to workers due to potential hazards such as lack of oxygen or toxic gases.

2. How do you determine whether a space is “confined”?

A confined space is typically defined by the Occupational Safety and Health Administration (OSHA) as an area with limited means for entry or exit, not designed for continuous human occupancy. It has the potential for hazardous conditions due to factors like poor ventilation or dangerous chemicals/gases.

3. Why is it important to properly identify confined spaces in the workplace?

Failure to identify, assess and manage risks associated with confined spaces can lead to serious accidents resulting in injuries or death among employees working in these environments. Keeping track of all potentially hazardous areas on worksites through regular monitoring helps ensure worker safety remains a top priority.

4. What safety precautions should be taken when entering a confined space?

Safeguards such as proper lighting & ventilation systems must be installed before entering any Confined area, along with using protective equipment, including respirators, hard hats, clothing, etc. Those entering such an environment should also receive adequate training on recognizing hazards that commonly occur while working inside these narrow enclosures. Additionally – Employers need to ensure an Emergency Action Plan (EAP) is deployed so appropriate response actions can be taken quickly if necessary.