Air Purification & Volatile Organic Compounds: Part 1

If you are a building or facilities manager, you’re probably quite preoccupied with air quality at the moment. (Heck, you don’t have to be a building or facilities manager to be preoccupied with indoor air quality right now.) You have a decent idea of most enemies you need to defeat; viruses, bacteria, dust, pollen, particulate matter, fungi, etc. However, there’s one villain who can be a bit more enigmatic: VOCs. But what exactly are VOCs, and how are they removed from the air? In this two-part article, we will give you the secrets you need to defeat this menace.

What are VOCs anyway?

Quite simply, VOC stands for “Volatile Organic Compound.” These substances are “volatile” meaning they evaporate easily and “organic” meaning they contain carbon. There are thousands of types of VOCs, ranging from highly complex synthetics to natural compounds. Most VOCs are clear liquids in their pure form, but their quick evaporation also means it’s very easy for humans to inhale them. They tend to enter the air of homes and businesses via a wide range of substances—paints, carpets, furniture, smoking, heating…the list goes on and on. Nearly any new product is going to offgas a certain amount of VOCs.

Let’s go over the properties and sources of 15 common VOCs found both in homes and in the workplace. We will also describe the effects of these 15 organic chemicals on human health. This is by no means a comprehensive list, but it should give you a good idea of your organic enemy’s methods.

Note: Nothing in this article should be construed as legal or medical advice, nor does it replace local, state, or federal safety guidelines. Instead, this article should be considered an invitation to learn more about VOCs and air quality.

List of common VOCs

Acetaldehyde: Fruity-smelling, flammable compound

• Formula: CH₃CHO
• Industries at risk for exposure: Food (packaging and preserving), pharmaceutical, manufacturing (paints, dyes, perfumes, lubricants, explosives, building materials).
• Sources of consumer inhalation: Acetaldehyde enters the air via wood and cigarette smoke.
• Health effects: As an air pollutant, acetaldehyde may irritate or damage the lungs, eyes, and blood vessels. It is also a possible carcinogen. (Fun fact: acetaldehyde is also to blame for hangovers, but that has to do with the acetaldehyde produced naturally by your body, not the acetaldehyde in the air.)
• Exposure limits: 200 parts per million (ppm) for an eight-hour shift.

Acetone: Pungent, colorless solvent

• Formula: CH₃COCH₃
• Industries at risk for exposure: According to the Australian government: “Acetone is produced as a result of manufacturing basic chemicals, plastic products, non-ferrous metals, iron and steel, fabricated metal products, motor vehicles and motor vehicle parts, photographic and scientific equipment, wood products, ceramic products, cement, lime, plaster and concrete products, meat and meat products, rubber products, paper, paper products and industrial machinery. Acetone is also emitted from printing processes, mineral, metal and chemical wholesaling, water supply, sewerage and drainage services and coal mining.” Well then, that covers nearly everything, doesn’t it?
  • So which industries are the greatest concern? According to the CDC, “Workers in certain industries, such as certain paint, plastic, artificial fiber, and shoe factories are likely exposed to much higher levels of acetone than the general population. Professional painters, commercial and household cleaners[...]” are also at risk.
• Sources of consumer inhalation: Acetone is produced by the body in small amounts. However, significant indoor air sources include nail polish remover, furniture polish, tobacco smoke, and wallpaper.
• Health effects: If consumed, acetone is bad news. When inhaled, however, acetone is merely a source of minor irritation…most of the time. Extreme and unusual levels of acetone exposure may cause menstrual irregularities, vomiting, fainting, and poor performance on neurobehavioral tests.
• Exposure limits: 250 ppm as a time-weighted average over a 10-hour shift.

Benzaldehyde: Smells like bitter almonds

Or rather, bitter almonds smell like benzaldehyde, since benzaldehyde is what gives them their smell.

• Formula: C₆H₅CHO
• Industries at risk for exposure: Cosmetics and plastic manufacturing are at risk. Food packagers working with artificial almond flavoring may also be exposed.
• Sources of consumer inhalation: Perfumes, dyes, flavorings, and solvents. Benzaldehyde might also offgas from certain home appliances.
• Health effects: As a vapor, benzaldehyde isn’t much to worry about beyond some minor irritation, at least according to one source. Another source we found says it may produce coughing and shortness of breath. As a liquid, skin contact may result in a rash. Some animal studies have demonstrated concerning health problems from exposure.
• Exposure limits: n/a

Benzene: Smells like gasoline

• Formula: C₆H₆ Benzene takes the form of a ring of carbons, each of which is bonded to the next carbon, as well as to a single hydrogen.
• Industries at risk for exposure: Shoemaking, printing, rubber, steel are all production processes which may expose one to benzene. Gas station attendants, firefighters, and chemists may also be exposed in the course of their duties.
• Sources of consumer inhalation: According to the CDC, indoor exposure may come from tobacco smoke, “glues, paints, furniture wax, and detergents.”
• Health effects: Short-term exposure to low levels can cause lung and throat irritation, while short-term exposure to high levels can cause dizziness, drowsiness, irregular heart beat, headaches, tremors, confusion, and death. Long-term, low-level exposure can reduce red blood cell count and damage the immune system. Benzene is linked to several types of leukemia in industries with high benzene exposure.
• Exposure limits: One ppm is the OSHA legal limit over an eight-hour shift.

1,3-Butadiene: Produced from petroleum to make synthetic rubber

• Formula: CH₂(CH)₂CH₂
• Industries at risk for exposure: Synthetic rubber production.
• Sources of consumer inhalation: Unless you work in a tire factory, your main exposure risk is motor vehicle exhaust. However, forest fires and cigarette smoke may also release this VOC.
• Health effects: According to the EPA, “Acute (short-term) exposure to 1,3-butadiene by inhalation in humans results in irritation of the eyes, nasal passages, throat, and lungs. Epidemiological studies have reported a possible association between 1,3-butadiene exposure and cardiovascular diseases. Epidemiological studies of workers in rubber plants have shown an association between 1,3-butadiene exposure and increased incidence of leukemia.”
• Exposure limits: One ppm over an eight-hour shift.

Ethanol: Grain alcohol

• Formula: CH₃CH₂OH
• Industries at risk for exposure: According to the Encyclopedia of Toxicology, “The primary industrial uses of this[...]alcohol are as an intermediate in the production of other chemicals and as a solvent. Ethanol is used in the manufacture of drugs, plastics, lacquers, polishes, plasticizers, and cosmetics.”
• Sources of consumer inhalation: You already know where to find ethanol if you want to imbibe it. As an inhalable VOC though, ethanol can be found in certain cleaners and detergents. It also is a component in some e-cigarettes.
• Health effects: Pretty bad if the exposure is high enough; it is, after all, a nervous system depressant. With a half life of five days, ethanol vapors tend to linger. Unless you work in the relevant industries though, you probably don’t have to worry about high exposure via inhalation. There are, however, two exceptions to this. Ethanol vapors can also be absorbed through vaping or pouring drinking alcohol over dry ice. These vapors may especially harm the brains of young adults.
• Exposure limits: The OSHA limit is 1,000 ppm as an average over an eight-hour shift.

Ethylene Glycol: Odorless as a gas

• Formula: Ready for this? It’s HOCH₂CH₂OH (a.k.a. 1,2 Ethanediol a.k.a. 1,2 Dihydroxyethane a.k.a. Glycol)
• Industries at risk for exposure & sources of consumer inhalation: Ethylene Glycol is used in everything from antifreeze to ballpoint pens as well as paints, plastics, varnishes, lacquers, and solvents. It is also used in the manufacturing of fiberglass.
• Health effects: According to the CDC, “Breathing ethylene glycol vapors may irritate eyes and lungs but is unlikely to cause systemic toxicity.” It can however, be extremely dangerous when ingested. It may damage the brain, the kidneys, and children in utero.
• Exposure limits: As an aerosol, 39 ppm, but exposure should be reduced to the lowest level possible.

Formaldehyde: Most well-known VOC

This is probably the VOC everybody hears the most about; it's practically a contaminant celebrity.

• Formula: CH₂O
• Industries at risk for exposure: Dry cleaning, hairdressing, healthcare, funeral homes, or the manufacturing of pressed wood.
• Sources: Any building with a lot of new pressed wood is at risk for high formaldehyde levels. Other sources can include dry-cleaned clothes, certain hair treatments, tobacco smoke, and combustion.
• Health effects: Indications of high formaldehyde can include watery eyes, coughing, wheezing, nausea, and skin irritation. It may also cause burning sensations in the eyes, nose, and throat. Formaldehyde might be carcinogenic.
• Exposure limits: Average levels are 0.1 ppm in the home, but can range up to 0.3 ppm. According to a 2011 study, “formaldehyde indoor air limit of 0.1 ppm should protect even particularly susceptible individuals from both irritation effects and any potential cancer hazard.”

d-Limonene & α-Pinene: Citrus and lemon scents

These are both terpenes, that is, aromatic compounds which plants produce to repel predators. As you might guess from the name, pinene smells like pine and limone smells like citrus.

• Formula: C₁₀H₁₆ How do they both have the same formula, you ask? Both have the same number of carbon and hydrogen atoms, but these atoms are arranged into different shapes.
• Industries at risk for exposure: Exposure to pinene can occur from the manufacture of turpentine or the processing of cannabis products. Presumably, exposure to limonene can occur during the manufacturing of cleaning products.
• Sources of consumer inhalation: As you might guess from the above, limonene scents many cleaning products, and pinene is used to make turpentine.
• Health effects: While these are natural compounds, the dose makes the poison. α-Pinene is a mere irritant in low amounts, but can affect the central nervous system at high exposure. D-limonene decreases vital capacity (i.e. how much air someone exhales…a measure of lung health) when inhaled at high levels.
• Exposure limits: 1,000 ppm for α-Pinene in the form of turpentine. D-limonene has an exposure limit of 150 mg/m₃ (the equivalent of 0.15 pmm) in Sweden, but that is the only guideline we could find. These are both eight-hour time-weighted averages.

Methylene Chloride: A colorless compound

OSHA claims this compound (a.k.a. Dichloromethane) has a “chloroform-like odor,” which isn’t particularly descriptive for those of us who (fortunately) haven’t smelt chloroform before.

• Formula: CH₂C_l2
• Industries at risk for exposure: According to OSHA, “Methylene chloride is used in various industrial processes, in many different industries including paint stripping, pharmaceutical manufacturing, paint remover manufacturing, and metal cleaning and degreasing.”
• Sources of consumer inhalation: Basically, home improvement projects—methyl chloride may be released by paint strippers, bathtub finishers, or metal degreasers.
• Health effects: According to the CDC, “Exposure can cause drowsiness, dizziness, numbness and tingling limbs, and nausea. It may cause cancer. Severe exposure can cause loss of consciousness and death.”
• Exposure limits: The OSHA limit is 25 ppm as an average over an eight-hour work shift.

Paradichlorobenzene: Distinctive, sweet smell

It's one of two chemicals that may be used in mothballs.

• Formula: C₆H₄C_l2 Paradichlorobenzene (a.k.a. 1,4 dichlorobenzene a.k.a. PDCB) is a ring like benzene, but with two chlorine atoms replacing two of the hydrogen atoms on opposite sides.)
• Industries at risk for exposure: Manufacturing of insecticides and certain cleaning products. PDCB is also used to produce a high performance polymer called PPS.
• Sources of consumer inhalation: PDCB is found in mothballs and toilet bowl deodorizers.
• Health effects: Short-term exposure can irritate the eyes, throat, and lungs. According to the EPA, long-term exposure “results in effects on the liver, skin, and central nervous system.” The nervous system effects are the most frightening; they include difficulty flexing one’s muscles or speaking.
• Exposure limits: The OSHA limit is 75 ppm as an average over an eight-hour shift.

Tetrachloroethylene: Clear liquid with a mildly sweet odor

• Formula: C₂Cl₄ 
• Sources and industries at risk for exposure: Tetrachloroethylene (a.k.a. Perchloroethylene a.k.a. PERC) is, somewhat controversially, a keystone tool of traditional dry-cleaning. It is also used for degreasing metal.
• Health effects: Bad news for dry cleaners, this VOC has a *lot* of negative health effects. According to the EPA: “Effects resulting from acute (short term) high-level inhalation exposure of humans to tetrachloroethylene include irritation of the upper respiratory tract and eyes, kidney dysfunction, and neurological effects such as reversible mood and behavioral changes, impairment of coordination, dizziness, headache, sleepiness, and unconsciousness.” The long-term effects get even worse, including an association with multiple types of cancers.
• Exposure limits: The OSHA limit is 25 ppm as an average over an eight-hour work shift.

Toluene: Clear liquid with a distinctive smell

• Formula: C₆H₅CH₃ (In other words, it looks a bit like a benzene ring with a methyl replacing one of the hydrogen atoms.)
• Industries at risk for exposure: Nail salons, as well as the production of gasoline, paints, and solvents. Gas station attendants may also be at risk if they work at a station with a leaky underground tank.
• Sources of consumer exposure: Toluene can get into the air while using certain paints and solvents. It is also an additive to gasoline, so that canister of gasoline in the garage may be exuding some toluene fumes.
• Health effects: Toluene (like almost everything else on this list) can irritate the upper respiratory tract. However, its primary target is the central nervous system. Short-term exposure to high levels can cause sleepiness, headaches, and nausea. It may also cause attention deficits and bodily deformities in children when exposed in utero.
• Exposure limits: Agencies can’t seem to agree on a safe amount. Limits range from 10 ppm to 200 ppm as a time-weighted average.

Xylene: Colorless, flammable liquid with a sweet odor

• Formula: C₆H₄(CH₃)₂ This molecule looks like a benzene with two methyls. There are three different possible arrangements along the benzene ring that these methyls can bind to, so there are three different types of Xylene. All of them share some properties though.
• Industries at risk for exposure: Nearly any form of manufacturing may provide risk for exposure; leather, rubber, and printing seem to top the list.
• Sources of consumer inhalation: Automotive exhaust is the main consumer exposure risk. Paints, solvents, lacquers, and removers may also contain Xylene, a.k.a. Dimethylbenzene.
• Health effects: Similarly to many VOCs on this list, minor exposure can cause nose, throat, and eye irritation. Chronic exposure may affect the nervous system, causing vision, memory, and muscle coordination problems. It may also damage the liver and kidneys.
• Exposure limits: The OSHA limit is 100 ppm as an average over an eight-hour work shift.

To be continued…

Alright, we think you get the idea. VOCs are extremely useful industrially, but most are bad news when they get into the air. In Part 2, we’ll discuss what you can actually do about it.

If, however, you’ve done enough reading about VOCs for one day, contact ActivePure to be put in touch with a local expert who can advise you on the best air purification methods for your home or business.