Volatile Organic Compounds

Why in news?

• India can slash emissions of volatile organic compounds (VOC) by 76 per cent in the next eight years by swapping all two- and three-wheelers with electric vehicles and all diesel-fuelled ones with Compressed Natural Gas (CNG), a new study has predicted.

More about the news:

• VOCs are carbon-containing chemicals released by petrol and diesel vehicles. They impact air quality and human health.
• However, VOCs can have a natural origin, too. Plants emit these chemicals to attract pollinators, defend themselves from pests and predators and adapt to environmental stress.
• Human-made VOCs are a cause for concern, yet they don’t draw enough attention.
• Benzene, a chemical that induces cancer, is the only VOC included in the ambient air-quality standards

About Volatile Organic Compound:

• Volatile organic compounds are chemicals that are lighter than air at room temperature.
• These compounds have a high vapor pressure and low water solubility.
• Many VOCs are human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants.
• They are also produced by plants, animals and microorganisms.
• Frequent exposure to volatile organic compounds leads to cancer and respiratory irritation.
• VOCs typically are industrial solvents, such as trichloroethylene; fuel oxygenates, such as methyl tert-butyl ether (MTBE); or by-products produced by chlorination in water treatment, such as chloroform.
• VOCs are often components of petroleum fuels, hydraulic fluids, paint thinners, and dry cleaning agents.
• VOCs are common ground-water contaminants.
• Examples of VOCs:
  • Benzene:
    • Benzene is most harmful of all the VOCs. It is called a carcinogen. It is commonly found in fuels, cigarette smoke, cars, and paints.
  • Perchloroethylene:
    • It is used for dry cleaning. It is also a VOC. The dry cleaned clothes carry these VOCs.

More about VOCs:

• Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects.
• Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors.
• VOCs are emitted by a wide array of products numbering in the thousands.
  • Examples: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials etc.

Role of VOC in the atmosphere

• 90% of the VOCs in the atmosphere is produced by the plants.
• The VOCs play a major role in chemical processes that occur in the atmosphere.
• The VOCs keep the atmosphere above it clean.
• Also, they react with harmful pollutants and neutralise their effects on the environment.
• VOCs are highly important for animal – plant communication.

Indoor VOCs:

• Some of the indoor sources:
  • Natural gas in cooking stoves and fuels used to heat homes
  • Cleaning solvents, disinfectants, and air fresheners
  • Glues and many arts and crafts materials like permanent markers,
  • Paints, paint strippers, varnishes etc.
  • Toys
  • Fire extinguishers
  • PVC pipes
  • Personal care products, cosmetics, and nail polish removers
  • Dry-cleaned clothing.
• The concentration of VOCs in homes is five times higher than its atmospheric concentration. Also, the VOCs can remain in homes for longer duration of time. Inhaling VOCs for longer duration leads to cancer.

Impact of VOC on human health:

• Irritation in eye, nose and throat, Headaches, asthma like symptoms, dizziness.
• Long-term exposure can cause serious damage to the liver and other organs.

Add ons:

• Many countries including USA, UK have not set any standards for the industrial limits of VOC.
• India sees no difference between VOC and other air pollutants.

PRACTICE QUESTION:

Consider the following statements regarding Volatile Organic Compounds:

1. They are chemicals that are lighter than air at room temperature

2. These compounds have high water solubility

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2

Answer