CO2 Analyzer for Air Quality & Leak Detection (in 2024)

A CO2 analyzer is used to monitor carbon dioxide air quality and to detect leaks in systems, instruments, fermentation, R&D, and process control. These units have a sensitive resolution of 1ppm and a high range of 5000 ppm.  This CO2 Air Quality and Leak Detector is designed with a built-in pump, making it excellent for detecting CO2 very fast and hence excellent to detect CO2 air quality and CO2 leaks. 

Is CO2 Dangerous?

Yes it is.

A CO2 leak can be dangerous, especially in indoor confined rooms and spaces. CO2 gas can accumulate and increase in concentration. When that happens, the CO2 gas can displace oxygen and lead to asphyxiation.

In low concentrations, carbon dioxide is generally not harmful to humans. However, in enclosed or poorly ventilated areas, such as in buildings or confined spaces, a CO2 leak can cause the concentration of the gas to rise to dangerous levels. Breathing in high levels of carbon dioxide can result in symptoms such as dizziness, shortness of breath, headache, confusion, rapid breathing, increased heart rate, and in extreme cases, loss of consciousness or death.

Who Uses a CO2 Air Quality and Leak Detector?

CO2 air quality and leak detectors are niche tools, but are used by various industries that employ CO2 gas. Here are some examples:

• Industrial and manufacturing facilities: CO2 leak detectors are often utilized in industrial settings where carbon dioxide is produced, stored, or used. These include power plants, breweries, beverage manufacturing facilities, chemical plants, and food processing plants.
• Restaurants and bars: Many restaurants and bars use carbon dioxide for carbonation in beverages such as soda and beer. CO2 leak detectors are employed to monitor storage areas, keg rooms, or any other spaces where carbon dioxide cylinders or systems are installed to prevent leaks and ensure a safe working environment.
• Laboratories: Laboratories that handle chemicals, conduct experiments, or have controlled environments may use CO2 leak detectors to monitor CO2 levels. This helps maintain appropriate conditions and prevent the buildup of carbon dioxide in enclosed spaces.
• Agricultural and horticultural settings: In certain agricultural practices, such as greenhouse cultivation or indoor farming, carbon dioxide is often supplemented to enhance plant growth. CO2 leak detectors can be employed to monitor CO2 levels in these environments and prevent excessive concentrations that may be harmful to humans or plants.

How to Test for CO2 Air Quality?

To test for a CO2 (carbon dioxide) leak, you can follow these general steps:

• Ensure Safety: Before conducting any tests, ensure that you are in a well-ventilated area or wear appropriate personal protective equipment (PPE) if necessary. If you suspect a significant CO2 leak or are experiencing symptoms of carbon dioxide poisoning, evacuate the area and seek fresh air immediately. Don't forget that CO2 is heavier than air, so if you are in a shaft or confined space, take extra precautions.

• Use a CO2 Leak Detector: Acquire a CO2 leak detector and use it at suspected leakage locations to pinpoint the increase in CO2 concentration. Leaks usually occur at gas lines, CO2 cylinders, junctions, and connectors.

• Monitor the CO2 ppm Readings: Allow the CO2 detector sufficient time to sample the air and provide accurate readings. We recommend moving 1 inch per 2 seconds. Monitor the detector's display or indicators for any changes in carbon dioxide levels. If the detector has an alarm function, ensure that it is activated and set to an appropriate threshold.

• Leak fixing: If as leak has been found. Take note of its location and tag the location. Ensure the breathable air does not exceed 5000ppm (otherwise evacuate). Address the leakage with an appropriate engineer or technician.

What Does CO2 Gas in Air Smell Like?

CO2 gas is a colorless, odorless gas, so it does not have a smell. This makes it difficult to detect a CO2 gas leak without the use of specialized equipment such as a CO2 leak detector.

How to Test for a CO2 Gas Leak?

If you suspect you have a CO2 gas leak, you should use a tool such as a CO2 Leak Detector.

• Begin by turning on the CO2 Leak Detector and allowing it to start operating after the countdown.
• Next, perform a quick bump test to ensure the analyzer is functional. You can do this by breathing at the input port. The point here is to confirm the CO2 Leak Detector is indeed operating.
• Once you have completed the bump test, take the CO2 Leak Detector and scan the area of interest, moving about 2 seconds per inch. Be patient and thorough to ensure you capture any CO2 gas.
• Typical areas of leakage occur around connections, valves, line bends, and junctions. Make sure to check these locations.
• Observe the detector's response. The units have a digital readout in PPM so it is very sensitive.
• If you have confirmed a CO2 gas leak, ensure you take appropriate action to maximize safety.

How Long Does the CO2 Sensor Last?

The lifespan of a CO2 (carbon dioxide) NDIR (Non-Dispersive Infrared) sensor last between 5 to 15 years. Generally, CO2 NDIR sensors are designed to have a long operational life with stable performance. The sensor's lifespan is influenced by factors such as operating temperature, humidity, exposure to contaminants, and the frequency of calibration and maintenance.

How often should I test or calibrate my CO2 Air Quality Analyzer?

You should bump test before using the CO2 leak detector. Calibration should be performed between 6 to 12 months. Calibration can be done by our lab or you can perform the calibration yourself with our video tutorials.

Will a CO2 Gas Leak set off Carbon Monoxide Detector?

No, a CO2 gas leak will not set off a carbon monoxide (CO) detector. Carbon monoxide detectors are specifically designed to detect and alert occupants to the presence of carbon monoxide gas. Carbon monoxide and carbon dioxide are two distinctly different gases. Don't get confused.

How Does a CO2 Gas Analyzer Work?

A CO2 gas analyzer typically uses a sensing technology called NDIR to detect the presence of carbon dioxide gas in the surrounding environment. Here's a basic overview:

• Infrared Light Source: The detector contains an infrared light source that emits a specific wavelength of infrared light, typically in the range of 4.2 to 4.4 micrometers. This wavelength is selectively absorbed by carbon dioxide molecules.
• Gas Sample Collection: The detector collects a sample of the surrounding air or gas mixture through an inlet or sampling port. For the CO2 Leak Detector, the unit has a pump that forces the air in the chamber for a faster leak detection response.
• Infrared Sensor: The detector incorporates an infrared sensor that consists of a detector element, typically made of pyroelectric or thermopile material. The sensor is designed to detect the infrared light after it has interacted with the gas sample.
• Absorption Measurement: When the infrared light passes through the gas sample, carbon dioxide molecules absorb some of the light at the specific wavelength emitted by the light source. The amount of light absorbed is directly proportional to the concentration of carbon dioxide present in the sample.
• Signal Conversion: The infrared sensor measures the intensity of the light that has passed through the gas sample and converts it into an electrical signal. The magnitude of the electrical signal corresponds to the amount of absorbed light and, in turn, indicates the concentration of carbon dioxide in the environment.
• Threshold and Alarm: The CO2 leak detector is typically programmed with a predetermined threshold or alarm level for carbon dioxide concentration. If the detected concentration exceeds this threshold, the detector triggers an audible and/or visual alarm to alert individuals of the potential CO2 leak.

How Should I Store my CO2 Air Quality Analyzer?

To ensure maximum sensor life and accurate measurements upon operation, it is recommended to store the CO2 Leak Detector in a moderate environment with a humidity level of 50%RH and a room temperature of approximately 70F. The unit should be kept in the hard waterproof case it was sold with for optimal storage conditions.

CO2 Air Quality History

• The exploration of CO2's impact dates back to the seventeenth century when Mayow proposed that igneo-aerial particles generated by candles were responsible for harming animals.
• In the eighteenth century, Lavoisier attributed these effects to CO2, which was then considered the cause of physiological issues linked to poor air quality. CO2 served as an indicator of whether the air was stale or fresh, rather than oxygen deficiency being the primary concern.
• In the nineteenth century, Max Josef von Pettenkofer challenged the idea that CO2 caused discomfort. Instead, he and Saeltzer suggested that the presence of organic material from human skin and lungs was responsible for negative effects attributed to poor ventilation. They proposed using CO2 levels as a surrogate for vitiated air and as an indicator of harmful airborne substances of unknown origin. Pettenkofer recommended 1000 ppmv of CO2 as a marker of insufficient indoor ventilation and 700 ppmv for bedrooms.
• In the early twentieth century, studies by Billings, Hermans, Flugge, Hill, and others showed that discomfort in poorly ventilated rooms was caused by warmth combined with odors in crowded spaces. Experiments with elevated CO2 levels (3% or 4%) and reduced oxygen levels (down to 17%) did not demonstrate significant negative effects, except for increased breathing rate and the need for cooling.
• Later research by Lemberg and Yaglou revealed that the response to human body odor could serve as a criterion for ventilation. Perceived odor intensity was used to establish ventilation rate requirements of approximately 7.5 to 10 L/s (15 to 20 cfm) per person, as proposed by Persily in 2015. During this time, CO2 was considered a marker of body odor perception, as humans emit both CO2 and bioeffluents in relation to their metabolism.
• Studies conducted in the latter part of the twentieth century by Fanger, Cain, and Iwashita, which used the acceptability of perceived air quality as the criterion for ventilation requirements, confirmed the findings of Yaglou and Lemberg. The research on body odor perception was utilized to develop ventilation standards by ASHRAE and the European Committee for Standardization (CEN).
• The 1989 edition of ASHRAE's ventilation standard, Standard 62 (later revised to Standard 62.1), initially set a CO2 limit of 1000 ppmv, but this was subsequently removed from later editions due to common misinterpretation.
  
  

Difference Between a CO2 and CO Leak Detectors?

CO and CO2 are two different gases. Often these two gases are confused and mixed up between people and can be dangerous. CO2 is carbon dioxide and CO is carbon monoxide. Our carbon monoxide leak detector is also available.

Conclusion

• A CO2 air quality and leak detector is a device designed to find CO2 gas leaks along various gas lines and connections.
• They help identify and locate potential CO2 leaks before they become a health hazard as CO2 can accumulate and deplete the oxygen in an indoor space.
• A CO2 air quality and leak detector should be used with an appropriate pinpoint probe, built-in pump (to increase detection speed), and display CO2 concentration in ppm.
• Be patient and slow when using a CO2 gas analyzer. It can take some time for good consistent measurements and dont forget not to exhale next to the device (exhalation distorts ppm CO2 readings).

About The Author

Dr. Kos Galatsis ("Dr.Koz") is the President of FORENSICS DETECTORS where the company operates from the scenic Palos Verdes Peninsula in Los Angeles, California. He is a subject matter expert on gas sensor technology, gas detectors, gas meters, and gas analyzers. He has been designing, building, manufacturing, and testing toxic gas detection systems for over 20 years.

Every day is a blessing for Dr. Koz. He loves to help customers solve their unique problems. Dr. Koz also loves spending time with his wife and his three children going to the beach, grilling burgers, and enjoying the outdoors.

Read more about Forensics Detectors here.

Email:  drkoz@forensicsdetectors.com
Phone: +1 424-341-3886

source https://www.forensicsdetectors.com/blogs/articles/co2-analyzer-air-quality-leak-detection

Gas Exposure Limit Tables

When working with gases, it's crucial to understand their properties and exposure limits to ensure safety and prevent potential health hazards. Gas exposure limits provide guidelines for the maximum allowable concentration of a gas in the air that workers can be exposed to without adverse effects. These limits vary depending on the specific gas and its properties, such as toxicity, flammability, and reactivity. 

Introduction to Exposure Safety

In this article, we will explore the key aspects of gas exposure limits and gas properties to help you make informed decisions when dealing with gases in your workplace. We used various sources to populate our tables, which included source data from:

OSHA Data
https://www.osha.gov/annotated-pels/table-z-1

NIOSH Data
https://www.cdc.gov/niosh/npg/

ACGIH Data
https://www.acgih.org/

WHO Data
https://www.ncbi.nlm.nih.gov/books/NBK574591/table/ch3.tab26/

EPA Data
https://www.epa.gov/criteria-air-pollutants/naaqs-table 

Acrylonitrile (C3H3N)

Acrylonitrile is a colorless, flammable, and toxic liquid with a pungent odor. It is used in the production of plastics, synthetic fibers, and rubber. Exposure to acrylonitrile can occur through inhalation, skin contact, or ingestion, and it is classified as a probable human carcinogen by the EPA and IARC.
Acrylonitrile Fact Sheet.

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 2 ppm average over 8 hours Ceiling: 10ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 1 ppm average over 10 hours Ceiling: 10ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:  2 ppm average over 8 hours

Acetylene (C2H2)

Acetylene (C2H2) is a colorless, flammable gas with a garlic-like odor. It is the simplest alkyne, consisting of two carbon atoms triple-bonded together with one hydrogen atom bonded to each carbon. Acetylene is used in welding and cutting torches, and as a raw material for various chemical syntheses.
Acetylene Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 2500 ppm average over 8 hours
American Conference of Government Industrial Hygienists (ACGIH)	NA

Ammonia (NH3)

Ammonia is a colorless gas with a pungent odor. It is composed of nitrogen and hydrogen (NH3). Ammonia is used in fertilizers, refrigerants, and cleaning products. Exposure to high concentrations can cause eye, nose, and throat irritation, and in severe cases, lung damage or death. Ammonia is flammable and explosive at high concentrations. 
Ammonia Fact Sheet.

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 50 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 25 ppm average over 10 hours Ceiling: 35ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   25 ppm average over 8 hours

Arsine (AsH3)

Arsine (AsH3) is a colorless, flammable, and highly toxic gas with a garlic-like odor. It is the simplest arsenic hydride, consisting of one arsenic atom bonded to three hydrogen atoms. Arsine is used in the semiconductor industry and is a byproduct of some industrial processes. Exposure can be fatal.
Arsine Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.05 ppm average over 8 hours Ceiling: 0.002 mg/m3 average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.0006 ppm never exceed this limit
American Conference of Government Industrial Hygienists (ACGIH)	TLV:  0.005 ppm average over 8 hours

Benzene (C6H6)

Benzene (C6H6) is a colorless, flammable liquid with a sweet odor. It is an aromatic hydrocarbon consisting of a ring of six carbon atoms, each bonded to one hydrogen atom. Benzene is a key component in the production of various chemicals, plastics, and pesticides, but is also a known carcinogen.
Benzene Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1 ppm average over 8 hours Ceiling: 5ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours Ceiling: 1ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   0.5 ppm average over 8 hours

Bromine (Br2)

Bromine (Br) is a reddish-brown liquid at room temperature with a strong, unpleasant odor. It is a halogen element and the only liquid nonmetallic element. Bromine is used in the production of flame retardants, water treatment chemicals, and pharmaceuticals. It is toxic and can cause skin and respiratory irritation.
Bromine Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours Ceiling: 0.3ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    0.1 ppm average over 8 hours

Carbon Disulfide (CS₂)

Carbon disulfide (CS2) is a colorless, volatile liquid with a sweet, ethereal odor. It consists of one carbon atom double-bonded to two sulfur atoms. Carbon disulfide is used as a solvent and in the production of rayon, cellophane, and pesticides. It is highly flammable and toxic, affecting the nervous system.
Carbon Disulfide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 20 ppm average over 8 hours Ceiling: 30 ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 1 ppm average over 10 hours Ceiling: 10 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    1 ppm average over 8 hours

Carbon Monoxide (CO)

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas. It is formed by the incomplete combustion of carbon-containing fuels. Carbon monoxide binds strongly to hemoglobin in red blood cells, reducing oxygen delivery to the body. Exposure to high levels can cause headaches, dizziness, confusion, and death by asphyxiation.
Carbon Monoxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 50 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 35 ppm average over 10 hours Ceiling: 200 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    25 ppm average over 8 hours
World Health Organization (WHO)	AQG: 4 µg/m3 average over 24 hours
Environmental Protection Agency (EPA)	NAAQS: 9 ppm  average over 1 hour

Chlorine (Cl2)

Chlorine (Cl) is a yellowish-green gas at room temperature with a pungent, irritating odor. It is a halogen element and a strong oxidizing agent. Chlorine is used in water treatment, as a disinfectant, and in the production of various chemicals and plastics. Exposure can cause respiratory issues and skin irritation.
Chlorine Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1 ppm not to be exceeded
National Institute for Occupational Safety & Health (NIOSH)	Ceiling: 0.5 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    0.5 ppm average over 8 hours STEL:  1 ppm average over 15 minute

  

Chlorine Dioxide (ClO₂)

Chlorine dioxide is a pale yellow gas with a pungent odor, used as a bleaching agent and disinfectant. It is a powerful oxidizer, effective against bacteria, viruses, and other microorganisms. In water treatment, it eliminates taste and odor compounds. However, it can be toxic if mishandled or inhaled.
Chlorine Dioxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 0.1 ppm average over 8 hours STEL:  0.3 ppm average over 15 minute

Cyclohexanol (C6H12O)

Cyclohexanol is a colorless, viscous liquid with a mild, sweet odor. It is an organic compound with the formula C6H11OH, consisting of a cyclohexane ring with a hydroxyl group attached. Cyclohexanol is used as a solvent and in the production of plastics, detergents, and pharmaceuticals. It is slightly soluble in water.
Cyclohexanol Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 50 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 50 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 50 ppm average over 8 hours

Diborane (B2H6)

Diborane is a colorless, highly reactive, and flammable gas with the formula B2H6. It has a repulsive odor and is lighter than air. Diborane is used as a reducing agent, rubber vulcanizer, and catalyst in organic synthesis. It is toxic and can spontaneously ignite in air, requiring careful handling.
Diborane Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    0.1 ppm average over 8 hours

Ethyl alcohol (Ethanol C2H5OH)

Ethyl alcohol, also known as ethanol (C2H5OH), is a colorless, flammable liquid with a characteristic odor. It is the active ingredient in alcoholic beverages and is also used as a solvent, disinfectant, and fuel additive. Ethanol is produced by fermenting sugars from various sources, such as grains and fruits. It has a wide range of applications in industries like pharmaceuticals, cosmetics, and chemical synthesis.
Ethyl Alcohol Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1000 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 1000 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    1000 ppm average over 8 hours

Ethylene Oxide (C2H4O)

Ethylene oxide is a colorless, flammable gas with a sweet, ether-like odor. It has the formula C2H4O and is the simplest cyclic ether. Ethylene oxide is used in the production of ethylene glycol, polyester fabrics, and detergents. It is also a powerful sterilant for medical equipment, but it is toxic and a known carcinogen.
Ethylene Oxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1 ppm average over 8 hours Ceiling: 5 ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.5 ppm average over 10 hours Ceiling: 5 ppm average over 10 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    1 ppm average over 8 hours

Formaldehyde (CH2O)

Formaldehyde is a colorless, flammable gas with a pungent odor. It has the formula CH2O and is the simplest aldehyde. Commonly used as a preservative in medical laboratories and mortuaries, formaldehyde is also found in household products like glues and pressed-wood. It is a known carcinogen and can cause irritation to the eyes, nose, and throat.
Formaldehyde Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.75 ppm average over 8 hours Ceiling: 2 ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.016 ppm average over 10 hours Ceiling: 0.1 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    0.3 ppm average over 8 hours

Fluorine (F2)

Fluorine is a pale yellow, highly reactive, and corrosive gas with the symbol F. It is the lightest halogen and the most electronegative element. Fluorine readily forms compounds with most other elements, and it is used in the production of fluoropolymers, such as Teflon, and in the enrichment of uranium for nuclear fuel. Due to its reactivity, fluorine is extremely dangerous and must be handled with great care.
Fluorine Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    1 ppm average over 8 hours STEL:  2 ppm average over 15 minute

Hexane (C6H14)

Hexane (C6H14) is a colorless, flammable liquid hydrocarbon with a gasoline-like odor. It is a non-polar solvent commonly used in industrial applications, such as oil extraction, cleaning agents, and adhesives. Hexane is also used in laboratories for chemical reactions and chromatography. Exposure to hexane can cause neurological damage and respiratory irritation.
Hexane Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 500 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 50 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 50 ppm average over 8 hours

Hydrazine (N2H4)

Hydrazine is a colorless, flammable liquid with the formula N2H4. It has a strong ammonia-like odor and is highly toxic. Hydrazine is used as a powerful reducing agent, a rocket propellant, and a blowing agent for plastics. It is also used in the production of pharmaceutical and agricultural chemicals. Hydrazine is carcinogenic and can cause severe burns, requiring extreme caution when handling.
Hydrazine Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.03 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    0.01 ppm average over 8 hours

 

Hydrogen Bromide (HBr)

Hydrogen bromide is a colorless, corrosive gas with a pungent odor, having the formula HBr. It is highly soluble in water, forming hydrobromic acid. Hydrogen bromide is used in the production of inorganic bromides, organic bromination reactions, and as a catalyst in industrial processes. It is toxic and can cause severe burns, requiring proper safety precautions when handling.
Hydrogen Bromide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 3 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 3 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   2 ppm average over 8 hours

Hydrogen Chloride (HCl)

Hydrogen chloride is a colorless, corrosive gas with a pungent odor and the formula HCl. It is highly soluble in water, forming hydrochloric acid. Hydrogen chloride is used in the production of vinyl chloride for PVC, in metal pickling, and in the oil and gas industry. It is toxic and can cause severe burns to the skin, eyes, and respiratory tract, necessitating proper safety measures during handling.
Hydrogen Chloride Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 5 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 5 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   2 ppm average over 8 hours

Hydrogen Cyanide (HCN)

Hydrogen cyanide is a colorless, highly poisonous gas or liquid with a faint, bitter almond-like odor. Its chemical formula is HCN. It is used in the production of plastics, synthetic fibers, and pesticides. Hydrogen cyanide inhibits cellular respiration, leading to rapid death. It was used as a chemical weapon and in Nazi gas chambers. Extreme caution is essential when handling this highly toxic substance.
Hydrogen Cyanide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 10 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 4.7 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    4.7 ppm average over 8 hours

Hydrogen Fluoride (HF)

Hydrogen fluoride is a colorless, corrosive gas or liquid with a strong, irritating odor. Its chemical formula is HF. It is highly soluble in water, forming hydrofluoric acid. Hydrogen fluoride is used in the production of fluoropolymers, fluorocarbons, and in the etching of glass and silicon wafers. It is extremely toxic and can cause severe burns, requiring specialized protective equipment and emergency procedures when handling.
Hydrogen Fluoride Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 3 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 3 ppm average over 10 hours Ceiling: 6 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 0.5 ppm average over 8 hours

Hydrogen Peroxide (H2O2)

Hydrogen peroxide is a clear, colorless liquid with the formula H2O2. It is a strong oxidizer and is used as a bleaching agent, disinfectant, and in rocketry as a propellant. Household solutions are typically 3-6% concentration, while industrial grades can reach 90%. It decomposes into water and oxygen gas. Ingestion of concentrated hydrogen peroxide can be fatal, and contact with skin or eyes causes irritation.
Hydrogen Peroxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 1 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    1 ppm average over 8 hours

Hydrogen Sulfide (H₂S)

Hydrogen sulfide is a colorless, flammable, and highly toxic gas with a characteristic rotten egg odor. Its chemical formula is H2S. It occurs naturally in volcanic gases, hot springs, and from bacterial breakdown of organic matter. Hydrogen sulfide is used in the production of sulfuric acid and as an analytical reagent. Exposure to high concentrations can cause rapid unconsciousness and death, requiring immediate evacuation and proper protective equipment in industrial settings.
Hydrogen Sulfide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 20 ppm average over 8 hours Ceiling: 50 ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 10 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:    1 ppm average over 8 hours

Isopropyl alcohol (IPA Propanol C3H8O)

Isopropyl alcohol, also known as rubbing alcohol, is a colorless, flammable liquid with a strong odor. It is commonly used as a disinfectant and solvent. With a chemical formula of C3H8O, it is often found in concentrations of 70-99%. Isopropyl alcohol has various applications in healthcare, cleaning, and industrial settings.
Isopropyl Alcohol Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 400 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 400 ppm average over 10 hours Ceiling: 500 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   200 ppm average over 8 hours STEL: 400 ppm average over 15 minutes

Methyl alcohol (Methanol CH₃OH)

Methyl alcohol, also known as methanol (CH3OH), is a colorless, flammable liquid with a slightly sweet odor. It is the simplest alcohol and is commonly used as a solvent, antifreeze, and fuel additive. However, methanol is highly toxic if ingested, inhaled, or absorbed through the skin, and can cause severe health issues, including blindness and death.
Methyl Alcohol Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 200 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 200 ppm average over 10 hours Ceiling: 250 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   200 ppm average over 8 hours STEL: 250 ppm average over 15 minutes

Nitric Oxide (NO)

Nitric oxide is a colorless, toxic gas with the formula NO. It is a free radical and is produced naturally in the body as a signaling molecule. Nitric oxide plays a crucial role in regulating blood pressure, neurotransmission, and immune response. Industrially, it is used in the production of nitric acid and as an intermediate in the synthesis of other chemicals. At high concentrations, nitric oxide can cause respiratory irritation and damage.
Nitric Oxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 25 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 25 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   25 ppm average over 8 hours

Nitrogen Dioxide (NO₂)

Nitrogen dioxide is a reddish-brown, highly reactive gas with a pungent, acrid odor. Its chemical formula is NO2. It is formed during high-temperature combustion processes, such as in vehicle engines and power plants. Nitrogen dioxide is a major component of smog and contributes to acid rain. Exposure can cause respiratory irritation, reduced lung function, and increased susceptibility to infections. It is also used in the production of nitric acid and as an oxidizing agent in various industrial processes.
Nitrogen Dioxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 5 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 1 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	OEL: 3 ppm  average over 8 hours STEL: 5 ppm average over 15 minutes
World Health Organization (WHO)	AQG: 25 µg/m3 average over 8 hours
Environmental Protection Agency (EPA)	NAAQS: 100 ppb  average over 1 hour

Ozone (O₃)

Ozone is a pale blue gas with a distinctive odor, composed of three oxygen atoms (O3). It occurs naturally in the upper atmosphere, forming the ozone layer that protects Earth from harmful UV radiation. At ground level, ozone is a major component of smog, formed by reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight. Ozone is a powerful oxidant and can cause respiratory irritation, aggravate asthma, and damage crops. It is also used in water treatment and as a disinfectant.
Ozone Fact Check

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours
World Health Organization (WHO)	AQG: 100 µg/m3 average over 8 hours
Environmental Protection Agency (EPA)	NAAQS: 0.70 ppm  average over 8 hours

Oxygen (O₂)

Oxygen is a colorless, odorless gas with the symbol O, essential for life on Earth. It makes up 21% of the atmosphere and is the third most abundant element in the universe. Oxygen is highly reactive and forms compounds with most other elements. It is used in industrial processes, medical treatments, and rocket propulsion. In its liquid and solid forms, oxygen is pale blue. All known forms of life depend on oxygen for cellular respiration and energy production.
Oxygen Fact Check

Agency	Limits
Occupational Safety & Health Administration (OSHA)	OSHA's Respiratory Protection Standard considers any atmosphere with an oxygen level below 19.5 percent to be oxygen-deficient and immediately dangerous to life or health.
National Institute for Occupational Safety & Health (NIOSH)	An oxygen-deficient atmosphere is defined as one with an oxygen concentration below 19.5% by volume at sea level.

Phosgene (COCl2)

Phosgene is a colorless gas with a suffocating odor reminiscent of moldy hay. Its chemical formula is COCl2. Phosgene is highly toxic and was used as a chemical weapon during World War I. It causes severe irritation and damage to the lungs, leading to fluid buildup (pulmonary edema) and potentially death. Industrially, phosgene is used in the production of plastics, pesticides, and pharmaceuticals. Strict safety measures and emergency response plans are essential when working with this dangerous substance.
Phosgene Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.1 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.1 ppm average over 10 hours Ceiling: 0.2 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 0.1 ppm average over 8 hours

Phosphine (PH₃)

Phosphine is a colorless, flammable, and highly toxic gas with a garlic-like odor. Its chemical formula is PH3. Phosphine is used in the semiconductor industry for doping silicon wafers and in the production of organophosphorus compounds. It is also used as a fumigant for stored grains and in the synthesis of flame retardants. Exposure to phosphine can cause respiratory irritation, pulmonary edema, and damage to the central nervous system. It can ignite spontaneously in air, requiring careful handling and storage.
Phosphine Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 0.3 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 0.3 ppm average over 10 hours Ceiling: 1 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 0.3 ppm average over 8 hours

Propane (C3H8)

Propane (C3H8) is a colorless, odorless, and flammable hydrocarbon gas. It is commonly used as a fuel for heating, cooking, and powering vehicles. Propane is stored and transported as a liquid under pressure in tanks or cylinders. It is a clean-burning alternative to other fossil fuels, with wide-ranging applications in both residential and industrial settings.
Propane Fact Sheet.

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1000 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 1000 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 1000 ppm average over 8 hours

Silane (SiH4)

Silane is a colorless, flammable gas with the chemical formula SiH4. It has a sharp, repulsive odor and is lighter than air. Silane is used in the semiconductor industry for depositing thin films of silicon dioxide and silicon nitride. It is also used in the production of solar cells and as a reducing agent in organic synthesis. Silane is pyrophoric, meaning it can ignite spontaneously in air, and it forms explosive mixtures with air. Proper ventilation, leak detection, and fire suppression systems are crucial when handling silane.
Silane Fact Sheet

Agency	Limits
National Institute for Occupational Safety & Health (NIOSH)	REL: 5 ppm average over 10 hours
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 5 ppm average over 8 hours

Sulfur Dioxide (SO2)

Sulfur dioxide is a colorless, pungent gas with the chemical formula SO2. It is formed during the combustion of sulfur-containing fuels and is a major air pollutant. Sulfur dioxide contributes to acid rain and can cause respiratory irritation, aggravating asthma and other lung conditions. In the food industry, it is used as a preservative in dried fruits and wine. Sulfur dioxide is also used in the production of sulfuric acid and as a bleaching agent for paper and textiles. Exposure to high concentrations can be life-threatening.
Sulfur Dioxide Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 5 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 2 ppm average over 10 hours Ceiling: 5 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 0.25 ppm average over 8 hours
World Health Organization (WHO)	AQG: 40 µg/m3 average over 24 hours
Environmental Protection Agency (EPA)	NAAQS: 7 ppb average over 1 hour

Styrene (C8H8)

Styrene is a colorless to yellowish, oily liquid with a sweet, floral odor. Its chemical formula is C6H5CH=CH2. Styrene is primarily used in the production of polystyrene plastics, rubber, and resins. It is also found in small amounts in natural sources like coffee and cinnamon. Styrene is highly flammable and can polymerize exothermically if not inhibited. Chronic exposure to styrene can cause neurological effects and increase the risk of certain cancers. Proper ventilation and personal protective equipment are necessary when working with this substance.
Styrene Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 100 ppm average over 8 hours Ceiling: 200 ppm average over 15 minutes
National Institute for Occupational Safety & Health (NIOSH)	REL: 50 ppm average over 10 hours Ceiling: 100 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 20 ppm average over 8 hours

Vinyl Chloride (C2H3Cl)

Vinyl chloride is a colorless, flammable gas with a sweet odor. Its chemical formula is C2H3Cl, featuring a double bond between the two carbon atoms. Vinyl chloride is primarily used in the production of polyvinyl chloride (PVC), a widely used plastic material. It is also a key ingredient in the manufacturing of various plastics, adhesives, and coatings. Vinyl chloride is a known human carcinogen, and chronic exposure can lead to liver damage and a rare form of liver cancer called angiosarcoma. Strict regulations and safety measures are in place to minimize occupational exposure and environmental contamination.
Vinyl Chloride Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 1 ppm average over 8 hours Ceiling: 5 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV: 1 ppm average over 8 hours

Xylenes (C6H4(CH3)2)

Xylenes are aromatic hydrocarbons consisting of a benzene ring with two methyl substituents. The three isomers are o-xylene, m-xylene, and p-xylene, differing in the positions of the methyl groups. Xylenes are colorless, flammable liquids with a sweet odor, commonly used as solvents and in the production of other chemicals.
Xylenes Fact Sheet

Agency	Limits
Occupational Safety & Health Administration (OSHA)	PEL: 100 ppm average over 8 hours
National Institute for Occupational Safety & Health (NIOSH)	REL: 100 ppm average over 10 hours Ceiling: 150 ppm average over 15 minutes
American Conference of Government Industrial Hygienists (ACGIH)	TLV:   100 ppm average over 8 hours STEL: 150 ppm average over 15 minutes

source https://www.forensicsdetectors.com/blogs/articles/gas-exposure-limit-tables