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A sneak peek about VOCs in our atmosphere

Mohammad Mahdee Mohammad Nasim, Nur Ili Hamizah Mustaffa

Perhaps you may have experienced the refreshing scent of the rainforest while hiking early in the morning or the alluring smell of refuelling car petrol. Chances are you have just inhaled VOCs. Volatile Organic Compounds (VOCs) are a collection of thousands of diverse chemicals that are composed of multiple configurations of carbon and hydrogen atoms. They are mostly present in the form of invisible gases since they easily evaporate at room temperature. They are also highly interactive with other chemicals in the atmosphere when exposed to sunlight. There are numerous family groups present in VOC classification, with alkanes and aromatics being the notable ones. A few examples of VOCs are ethane (C2H6) from the alkane family and benzene (C6H6) from the aromatic family. The alkane family includes molecules with linear structures while the aromatic family includes molecules with ring structures.

Although there is a wide spectrum of chemicals with many exceptions, VOCs are generally regarded as pollutants. Adequate exposure to it such as toluene (C7H8) from adhesive solvents is known to harm the heart and nervous system. Inhaling formaldehyde (CHâ‚‚O) from paints can lead to symptoms like dyspnoea, headaches, and nausea. Some chlorinated VOCs classified as irritants are linked to cardiovascular, neurological, and carcinogenic health effects. Moreover, numerous VOCs present in the atmosphere, like benzene, are carcinogens that damage the immune system, bone marrow, and brain. Benzenes are typically a by-product of petrol vapour and combustions in vehicles. Therefore, it is wise to refrain from inhaling any scent of petrol, car exhaust, and other products such as paints and adhesives to prevent potential health risks.

Since VOCs are highly interactive in the atmosphere, they often react to other air pollutants like nitrogen oxides (NOx) to produce ozone gases (O3). Generally, ozone gases at high altitudes like the stratosphere are beneficial to us as they help to protect life from the ultraviolet rays of sunlight. However, ozone gases produced by VOCs are typically present at ground level and lower altitudes like the troposphere which harms human health. Ground-level ozone irritates the eyes, nose, and throat while worsening asthma and bronchitis. It also reduces plant metabolism since it hinders the plant’s ability to photosynthesize and produce food. This impairs plant growth and disrupts ecosystem stability due to inadequate energy flow in food chains.
Given the alarming danger that VOC offers to people and the environment, one may ask where does VOC come from? As hinted, yes, VOCs come from human activities. The combustion of gasoline in our vehicles’ engines emits VOCs into the ambient air. These fossil fuels are also used to generate electricity in our power grids. Besides, the usage of solvents aerosols, paints, thinners, and wax in the industry amplifies VOC emissions. Therefore, it is quite unescapable for city residents to live without inhaling it. Moreover, VOCs are also being emitted by the natural environment, be it from leaves, microbes, insects, soils, and even the seas. Interestingly, VOCs are pivotal in the interaction between plants and animals as plants rely on VOCs to attract pollinators while gaining protection from potential predators.

But how serious are the emissions? It is estimated 150 teragrams of carbon are released annually as VOCs from anthropogenic sources globally. To put it in perspective, it is equivalent to the mass of 24 million African elephants. Meanwhile, approximately 1,150 teragrams of carbon are released annually as VOCs from biological sources globally, which is 10 times more than what humans emit! However, this fact disregards factors like local vegetation, climate, and level of industrial activity that do affect the relative VOC levels, varying from place to place. For example, the Malaysian state of Penang is a highly industrialized and populated region as it is one of the nation’s largest economies. Hence, the growing industrial sector and continuous vehicular traffic prominently influence the local VOC levels in the atmosphere compared to natural emissions.

All in all, studies on trends and atmospheric VOC levels are still ongoing with an extensive focus on rapidly developed cities. This is because cities act as a powerhouse for industrial emissions while being a region that houses the majority of the human population. VOCs’ health hazards and their role as ground-level ozone producers are well documented; therefore, more efforts are required to combat and mitigate this pollutant from increasing and declining the air quality. This action is in line with the 13rd Sustainable Development Goal (SDG) of Climate Action, which calls for immediate action to combat climate change and its consequences.

Tarikh Input: 08/02/2023 | Kemaskini: 08/02/2023 | masridien

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