Various researches and studies have proved that air pollutants can cause serious illness and can even increase the mortality rate. One such group of pollutants is volatile organic compounds (VOCs) that are majorly produced during combustion and are composed of various chemical species of organic nature such as benzene, toluene, esters, methane, perfluorocarbons, chlorohydrocarbons, trichloroethylene, chloroform, paraffin, and ketones. VOCs have less water solubility and are less volatile at ambient room temperature. Exposure for a long time to polluted air can cause serious health damages. For example, long-time exposure to a few parts per million (ppm) of volatile organic compounds (VOCs) can cause long-term diseases (Tang et al., 2006).
VOCs are considered as human carcinogen and long-time exposure to VOCs may cause diseases like reduced pulmonary function, asthma, nasopharyngeal cancer, and haematological problems (Soni et al., 2018 Kampa and Castanas, 2008).
Polycyclic aromatic hydrocarbons (PAHs) are a group of VOCs containing several benzene rings. It mainly includes naphthalene, phenanthrene, and pyrene, which have been identified as carcinogenic VOCs (Kim et al., 2007).
VOCs generate from both natural and anthropogenic sources. Over the years, industrialisation and urbanisation have contributed heavily to the VOC emissions.
Most every day activities of human life such as cooking, painting, smoking, driving, and construction adds up largely to the VOC concentrations.
- Activities like exploitation, storage, refining, transport, and consumption of fossil fuels also leads to VOC emissions.
- Fossil fuel like asphalt blowing contributes 27kg VOC/m3, cooking emits 0.4 kg VOCs/m3 feed and the catalytic cracking process contributes 0.25-0.63 kg VOCs/m3 feed (Zhang et al., 2017).
- VOCs are also generated from chemical and refinery industries, aromatics, hydraulic fluids, petroleum fuels, paints, ink, and dry-cleaning agents. Other than point sources, non-point sources like leaks or evaporation during different industrial activities also add up to the atmospheric VOCs. Almost 2.9 kgt-1of VOCs have been found at the service stations in the vapor phase (Zhang et al., 2017).
- Coal and gas also produce a significant amount of VOCs. Apart from anthropogenic sources, natural sources also produce VOCs from biogenic emissions of terrestrial and Oceans.
- The natural emission of VOCs is reported to be far greater than anthropogenic emissions.
- Natural emission can almost go up to 1150 Tg C/year whereas human activities contribute only about 142 Tg C/year (Li et al., 2002).
- The most common biogenic VOCs are isoprene and monoterpenes (Muller et al., 1992).
Health effects of VOC’s
Exposure to VOCs can, directly and indirectly, affect human health for a short as well as for a long time causing acute and chronic health effects respectively.
- VOC compounds such as toluene, benzene, ethylbenzene, and xylene are associated with cancer (Manisalidis et al., 2020).
- VOCs are omnipresent in the indoor environment having a concentration higher than the outdoors (Brown, 2002).
- Low-level exposure to aldehyde leads to respiratory health problems like throat infection, shortness of breath, eye irritation, and tightness in the chest (Main and Hogan, 1993).
- Long-term exposure or high concentration can cause nasal tumors and acute or chronic toxicity (Kamal et al., 2016).
- Likewise, formaldehyde can cause nasopharyngeal cancer, reduced pulmonary function, leukemia, and sick building syndrome (SBS) (Kim and Shim, 2010).
- High concentration can result in unconsciousness, dizziness, and even death.
- Systematic damage to human health is caused by benzene that causes leukemia and lymphomas.
- As low as 2 percent of benzene in the air is lethal if exposed for 5-10 min only (Zhang et al., 2017).
- Alcohols, mainly ethanol, isopropanol, and n-butane may result in severe nervous system depression.
- It also results in the formation of aldehydes which has been proven to be dangerous for human health (Zhu and Wu, 2015).
- Furthermore, a Low concentration of ketones would instigate the irritation of the eyes, nose, and throat.
- However, exposure to high concentrations would lead to central nervous system depression, headache, and nausea.
- Not just the outdoor air quality, but the indoor air quality too is linked closely with human health as almost 85% of time humans spent is indoors.
With the current pandemic situation this percentage is even higher and so is the risk to human health.
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- Brown, S. K. (2002). Volatile organic pollutants in new and established buildings in Melbourne, Australia. Indoor air, 12(1), 55-63.
J.-F. Müller, Geographical distribution and seasonal variation of surface emissions and deposition velocities of atmospheric trace gases, J. Geophys. Res.: Atmos. 97 (1992) 3787–3804
- Kampa, M., & Castanas, E. (2008). Human health effects of air pollution. Environmental pollution, 151(2), 362-367
- Kamal, M. S., Razzak, S. A., & Hossain, M. M. (2016). Catalytic oxidation of volatile organic compounds (VOCs)–A review. Atmospheric Environment, 140, 117-134.
- Kim, S. C., & Shim, W. G. (2010). Catalytic combustion of VOCs over a series of manganese oxide catalysts. Applied Catalysis B: Environmental, 98(3-4), 180-185.
- Kim, S. C., Nahm, S. W., Shim, W. G., Lee, J. W., & Moon, H. (2007). Influence of physicochemical treatments on spent palladium based catalyst for catalytic oxidation of VOCs. Journal of hazardous materials, 141(1), 305-314.
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- Manisalidis, I., Stavropoulou, E., Stavropoulos, A., & Bezirtzoglou, E. (2020). Environmental and health impacts of air pollution: a review. Frontiers in public health, 14.
- Tang X, Chen J, Li Y, Li Y, Xu Y, Shen W (2006) Complete oxidation of formaldehyde over Ag/MnO x–CeO 2 catalysts. Chem Eng J 118:119–125
- Soni, V., Singh, P., Shree, V., & Goel, V. (2018). Effects of VOCs on human health. In Air pollution and control (pp. 119-142). Springer, Singapore.
- Zhang, X., Gao, B., Creamer, A. E., Cao, C., & Li, Y. (2017). Adsorption of VOCs onto engineered carbon materials: A review. Journal of hazardous materials, 338, 102-123.
- Zhu, Z., & Wu, R. J. (2015). The degradation of formaldehyde using a [email protected] TiO2 nanoparticles in presence of visible light irradiation at room temperature. Journal of the Taiwan Institute of Chemical Engineers, 50, 276-281.