What really are VOCs, or Volatile Organic Compounds?
Volatile organic compounds, or VOCs, are compounds known to have high vapor pressure and low water solubility. Their composition makes it possible for evaporation to occur under normal indoor atmospheric conditions of temperature and pressure; this causes atmospheric photochemical reactions to occur.
VOCs are generally man-made organic chemicals that are often used as a base material for producing both industrial and consumer products. Without these compounds, we wouldn't have the thousands of products and materials necessary for everyday modern life.
Potential Dangers of VOCs
Although necessary for many important products, VOC emissions pose certain dangers. When left untreated, VOCs compromise air and water quality and lead to harmful health effects on humans and the earth's ecosystems.
The high vapor pressure of VOCs means they volatilize (evaporate) under ambient pressure and temperature. Once released into the air, VOCs can react with nitrogen oxides and carbon monoxide to produce ozone pollution. This is the United States' most widespread outdoor air pollutant and is linked to health issues affecting cardiovascular and respiratory systems. Ozone pollution also depletes our ecosystems by damaging crops, trees, sensitive vegetation, and marine microorganisms, putting our food system at risk.
Furthermore, VOCs easily dissolve into water and cause contamination. They become more persistent as they dissolve into groundwater and can migrate through both unsaturated and saturated zones of water aquifers. Although some of these VOCs undergo degradation during this process, many of them continue on to contaminate drinking water supply wells.1
Common VOCs and Emission Sources
VOCs are typically produced within industrial-level processes. They come in the forms of industrial solvents, additives, or by-products from manufacturing and treatment plants (i.e. water treatment). VOCs that are present in the environment originate from gasoline and diesel emissions, wood burning, oil and gas extraction and processing, and industrial equipment emissions.
Examples of VOCs include, but are not limited to:
• Benzene
• Formaldehyde
• Methylene Chloride
• Tetrachloroethylene
• Toluene
• Xylene
• 1,3-Butadiene
For a complete list of chemicals classified as VOCs, visit the CDC's Toxic Substances Portal.
You can also visit the EPA's Substance Registry on Volatile Organic Compounds for details on related substances and regulations.
Industrial Applications Which Emit VOCs
The manufacturing and industrial use of the products below require or create VOCs that are subsequently emitted into the atmosphere:
• Paints and Dyes
• Coatings and Laminates
• Pharmaceuticals
• Refrigerants
• Automotives
• Electronics
• Carpets
• Wood Products
• Adhesives
• Rubber Products
• Plastics
• Agriculture
Products That Contain VOCs
Products that contain VOCs as a base material later release these compounds into the air as they are used or stored over time. Some examples include:
• Gasoline
• Diesel Fuel
• Hydraulic Fluids
• Petroleum-based products
• Carpets
• Paints and Paint Thinners
• Varnishes
• Glues
• Dry Cleaning Agents
• Pest Fumigants
Curious as to how your state ranks on VOC emissions? Look into this interactive map from the U.S. Sustainable Development Report (2021) showcasing the ranks, trends, and values by state.
Regulations
The EPA regulates the emissions of VOCs to the outdoors to prevent the formation of ozone, a component of photochemical smog. Many VOCs create photochemical smog by reacting with nitrogen oxides (NOx) and carbon monoxide (CO) in the atmosphere while sunlight is present.
EPA regulations include a list of compounds that are exempt from being classified as VOCs for various reasons. Excerpt from “Volatile Organic Compounds” Definition per 40 CFR Part 51.100(s):
" Volatile organic compounds (VOC) means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions. (1) This includes any such organic compound other than the following, which have been determined to have negligible photochemical reactivity: methane; ethane; …. etc. " 4
Furthermore, some states follow their own definitions and lists of exempted compounds, so it is vital to investigate if there are any local regulations in your area of operations.
Unsure about what regulations your operations are subject to? Find out more information by visiting the National Volatile Organic Compound Emission Standards.
Abatement
VOCs are only one component contributing to air pollution, and the different sources producing these emissions make it difficult for one solution. Until we can figure out a way to create products without forming the VOCs themselves, industries will have to treat VOCs after they are used or generated.
Industries can address VOC emissions by utilizing strategies that fit their specific application and operational needs.
VOC Abatement Technology Options
• Thermal Oxidizer - Destruction of VOCs is accomplished by raising the incoming process stream to the required temperature above the pollutant(s) activation energy in the presence of oxygen.
• Recuperative Thermal Oxidizer - Ideal for Moderate VOC concentrations due to the system's heat exchanger component and its continuous steady state operating conditions.
• Regenerative Thermal Oxidizer (RTO) -Works well if the application has relatively low VOC loading in relation to a high exhaust flow rate that does not contain significant particulate or condensable matter (high volume, low VOC air streams).
• Direct Fired Thermal Oxidizer (AKA Enclosed Flares) - Designed for high VOC concentrations and typically offers DRE in excess of 99%
• Scrubbers - Appropriate for some applications depending on the required removal efficiency.
• Carbon Absorption - For low VOC concentrations
• Catalytic Oxidizer - These systems accomplish oxidization at lower temperatures than straight thermal oxidation and are most appropriately used in process applications with lower concentrations of VOCs.
Want concrete examples of how Pollution Systems' equipment can aid your facility in APC? View our case studies in which we discuss outcomes real customers have achieved from our systems.
Sources
1U.S. Geological Survey (2019). Volatile Organic Compounds (VOCs). Retrieved July 25, 2022, from https://www.usgs.gov/mission-areas/water-resources/science/volatile-organic-compounds-vocs.
2U.S. Environmental Protection Agency (2021). Our Nation's Air: Trends Through 2020. Retrieved July 25, 2022, from https://gispub.epa.gov/air/trendsreport/2021/.
3U.S. Environmental Protection Agency (2021). Our Nation's Air: Trends Through 2020. Retrieved July 25, 2022, from https://gispub.epa.gov/air/trendsreport/2021/.
4U.S. Environmental Protection Agency (2021). What is the definition of VOC?. Retrieved July 25, 2022, from https://www.epa.gov/air-emissions-inventories/what-definition-voc.
