Asphyxiants Deprive the Body of Oxygen: Understanding Hazardous Chemical Safety

Asphyxiants are hazardous substances that can prevent the body from getting or using enough oxygen. Exposure to these substances can cause breathing difficulty, unconsciousness, serious health effects, or even death. Asphyxiants are especially dangerous in confined spaces, storage areas, tanks, vessels, laboratories, manufacturing plants, and other workplaces where gases can collect.

Understanding how asphyxiants work is an important part of hazardous chemical safety. OSHA explains that asphyxiants can cause suffocation by reducing oxygen in the atmosphere or by interfering with the body’s ability to take up or use oxygen.

The Safety Master helps organizations improve workplace safety through risk assessment, safety audits, training, and practical safety management solutions.

What Are Asphyxiants?

Asphyxiants are gases or chemicals that can cause oxygen deprivation. They can affect the body in two main ways.

Simple asphyxiants reduce the amount of oxygen available for breathing by replacing or displacing oxygen in the surrounding air. Nitrogen, helium, argon, neon, methane, and carbon dioxide are examples that can create an asphyxiation hazard when present at dangerous concentrations.

Chemical asphyxiants interfere with the body’s ability to transport, absorb, or use oxygen. Carbon monoxide and hydrogen cyanide are examples of chemical asphyxiants.

Both types require proper identification, monitoring, control measures, and worker training.

How Do Asphyxiants Affect the Body?

The human body needs oxygen for normal brain, heart, muscle, and organ function. When oxygen availability becomes too low, the body cannot function normally.

An oxygen-deficient atmosphere may result from gases displacing oxygen or from chemical reactions that consume oxygen. OSHA generally considers an atmosphere with less than 19.5% oxygen to be oxygen deficient.

Initial effects can include:

• Headache
• Dizziness
• Weakness
• Confusion
• Rapid breathing
• Poor coordination
• Difficulty concentrating
• Loss of consciousness

At severe oxygen deficiency, a person may become unable to escape without assistance, and exposure can become fatal.

Types of Asphyxiants

Simple Asphyxiants

Simple asphyxiants do not necessarily cause toxicity through a specific chemical action. Instead, they can reduce oxygen concentration by occupying space that would normally contain breathable air.

Common examples include:

• Nitrogen
• Helium
• Argon
• Neon
• Methane
• Carbon dioxide

These gases can be particularly dangerous in enclosed or poorly ventilated areas.

Chemical Asphyxiants

Chemical asphyxiants can interfere with the body’s ability to transport or use oxygen.

Examples include:

• Carbon monoxide
• Hydrogen cyanide
• Hydrogen sulfide

Some chemical asphyxiants can cause serious effects even when the atmosphere is not simply oxygen-deficient because they interfere with normal physiological processes.

Where Are Asphyxiant Hazards Commonly Found?

Asphyxiant hazards can occur in many industrial and workplace environments.

Common locations include:

• Confined spaces
• Storage tanks
• Process vessels
• Sewage systems
• Manholes
• Chemical plants
• Manufacturing facilities
• Laboratories
• Welding areas
• Gas storage areas
• Refrigeration systems
• Waste treatment facilities
• Areas using inert gases

Confined spaces are particularly important because gases can accumulate and ventilation may be inadequate. OSHA identifies oxygen-deficient atmospheres as a major concern during confined-space work.

Why Are Asphyxiants Dangerous in Confined Spaces?

A confined space may have limited openings and poor natural ventilation. If an asphyxiant gas enters or is generated inside the space, the oxygen concentration can decrease quickly.

Workers may not recognize the danger because many simple asphyxiant gases are colorless and odorless. OSHA notes that simple asphyxiants are a particular concern in confined spaces because they may provide little or no warning before dangerous oxygen deficiency occurs.

For this reason, workers should never enter a potentially hazardous confined space based only on visual inspection or the absence of an unusual smell.

How to Control Asphyxiant Hazards

Effective hazardous chemical safety requires a combination of engineering controls, safe procedures, monitoring, training, and emergency planning.

Identify the Hazard

First, identify all chemicals and gases used, stored, generated, or released in the workplace.

Review:

• Safety Data Sheets (SDS)
• Chemical inventories
• Process information
• Piping and instrumentation
• Previous incidents
• Confined-space assessments
• Emergency procedures

Test the Atmosphere

Atmospheric testing is essential before entering an area where oxygen deficiency may exist.

Testing may include:

• Oxygen concentration
• Flammable gases and vapors
• Toxic gases
• Other contaminants relevant to the process

OSHA requires atmospheric testing in applicable enclosed-space situations and specifies direct-reading instruments for oxygen testing.

Provide Proper Ventilation

Adequate ventilation can help prevent dangerous concentrations from developing.

Where an oxygen deficiency or hazardous gas is identified, appropriate forced-air ventilation may be required to maintain a safe atmosphere.

Ventilation should be designed and operated according to the specific chemical and process hazard.

Use Gas Detection Systems

Fixed or portable gas detectors can help identify dangerous atmospheric conditions.

Depending on the workplace, monitoring may include:

• Oxygen sensors
• Toxic gas detectors
• Flammable gas detectors
• Continuous monitoring systems
• Personal gas monitors

Monitoring equipment should be properly selected, maintained, calibrated, and tested.

Apply Permit-to-Work Controls

For hazardous confined-space activities, a permit system can help ensure that required precautions are completed before entry.

The permit process may address:

• Atmospheric testing
• Isolation
• Ventilation
• Communication
• Personal protective equipment
• Rescue arrangements
• Competent personnel
• Entry and exit requirements

Provide Appropriate Respiratory Protection

Respiratory protection must be selected according to the actual hazard.

OSHA considers oxygen-deficient atmospheres to be IDLH in its respiratory protection requirements, with specific provisions for atmosphere-supplying respirators.

A normal air-purifying respirator should not be assumed to provide protection against an oxygen-deficient atmosphere.

Emergency Response to Asphyxiant Exposure

Emergency response should be planned before an incident occurs.

If a worker collapses in an area suspected of having an oxygen-deficient or contaminated atmosphere, other workers should not enter the area without proper assessment and rescue equipment.

Important emergency actions include:

• Raise the alarm.
• Keep unprotected personnel away.
• Contact the emergency response team.
• Isolate the source when it can be done safely.
• Assess the atmosphere using appropriate equipment.
• Ventilate the area when appropriate.
• Use trained rescue personnel and suitable respiratory protection.
• Provide medical attention to exposed workers.

Unplanned rescue attempts can create additional victims. Proper rescue planning and training are therefore critical.

Importance of Hazardous Chemical Safety Training

Workers who handle hazardous chemicals or work in areas where asphyxiants may be present need appropriate training.

Training should cover:

• Identification of asphyxiant hazards
• Chemical labels and SDS
• Oxygen-deficiency hazards
• Gas detection
• Confined-space safety
• Ventilation
• PPE
• Respiratory protection
• Emergency response
• Rescue procedures
• Safe work practices

Training should be practical and relevant to the actual workplace.

Role of Risk Assessment in Asphyxiant Safety

A proper risk assessment helps identify where asphyxiant exposure could occur and determines suitable control measures.

A risk assessment can consider:

1. Hazard identification
2. Chemical properties
3. Possible release scenarios
4. Exposure routes
5. Existing controls
6. Atmospheric monitoring
7. Consequence of exposure
8. Emergency response
9. Required PPE
10. Additional control measures

Using the hierarchy of controls can help organizations prioritize effective measures before relying only on PPE.

Best Practices for Preventing Asphyxiation

Organizations can reduce asphyxiation risks by following good safety practices:

• Maintain an updated chemical inventory.
• Keep SDS information available.
• Identify oxygen-deficiency areas.
• Test confined spaces before entry.
• Use calibrated gas detection instruments.
• Maintain effective ventilation.
• Isolate hazardous energy and chemical sources.
• Follow confined-space entry procedures.
• Provide suitable PPE and respiratory protection.
• Train workers and emergency responders.
• Conduct regular safety audits.
• Review incidents and near misses.
• Maintain emergency rescue plans.

The exact controls should always be based on the chemicals, processes, workplace conditions, and applicable regulations.

Conclusion

Asphyxiants are serious workplace hazards because they can deprive the body of oxygen or interfere with the body’s ability to use oxygen. Simple asphyxiants can displace oxygen from the atmosphere, while chemical asphyxiants can interfere with normal oxygen transport or utilization.

Atmospheric testing, ventilation, gas detection, confined-space controls, worker training, emergency planning, and suitable respiratory protection are important elements of hazardous chemical safety. OSHA identifies oxygen concentrations below 19.5% as oxygen deficient in its workplace safety requirements.

For professional guidance on workplace risk assessment, chemical safety, safety training, and safety management, The Safety Master can help organizations develop practical approaches for safer workplaces.

FAQs

1. What are asphyxiants?

Asphyxiants are gases or chemicals that can cause oxygen deprivation. Simple asphyxiants can displace oxygen from the air, while chemical asphyxiants can interfere with the body’s ability to use or transport oxygen.

2. What is an example of a simple asphyxiant?

Nitrogen is a common example of a simple asphyxiant. Other examples include helium, argon, neon, methane, and carbon dioxide. These gases can become dangerous when they reduce oxygen to unsafe levels.

3. What is an oxygen-deficient atmosphere?

An oxygen-deficient atmosphere is an atmosphere containing less than 19.5% oxygen by volume under OSHA workplace criteria. Such an atmosphere can create a serious risk to workers.

4. How can asphyxiant hazards be controlled?

Asphyxiant hazards can be controlled through hazard identification, atmospheric testing, ventilation, gas detection, isolation, safe work procedures, confined-space controls, worker training, and appropriate respiratory protection.

5. Why are asphyxiants dangerous in confined spaces?

Confined spaces can have poor ventilation, allowing gases to accumulate and oxygen levels to decrease. Some asphyxiant gases may also be colorless and odorless, making atmospheric testing and monitoring essential.