Air pollution exerts a devastating impact on various environmental components, encompassing air, groundwater, and soil, while posing a severe threat to living organisms. The ecological ramifications of air pollution are underscored by phenomena such as acid rain, global warming, the greenhouse effect, and climate changes. Monitoring and controlling air pollutants is crucial to safeguarding air quality and protecting human health and the environment. The specific pollutants of concern can vary depending on the region, industrial activities, and local sources of emissions.
Microscopic particles, often originating from vehicle emissions, industrial processes, and natural sources, can deeply penetrate the respiratory system upon inhalation.
The World Health Organization (WHO) reports on six major air pollutants, namely:
- particle matter (PM10 and PM2.5),
- ground-level ozone (O3),
- carbon monoxide (CO),
- sulfur dioxide (SO2),
- nitrogen oxides (NOx), and
- lead (Pb).
Long-term exposure to PM10 and PM2.5 has been associated with respiratory and cardiovascular diseases, including asthma, bronchitis, and heart attacks. Additionally, PM2.5 is of particular concern due to its ability to reach deeper into the lungs and potentially enter the bloodstream, posing a heightened risk for adverse health impacts, such as aggravated respiratory conditions and an increased likelihood of premature mortality. Efforts to reduce exposure to particulate matter involve stringent air quality regulations, improved emission control technologies, and public awareness initiatives.
Major Air Pollutants
| Pollutant | Description | Significance | Remarks |
| Particulate Matter (PM1, PM2.5 and PM10) | Concentrations of ultrafine, fine and coarse airborne particles. | Indicates air quality and potential health risks. | Particulate matter (PM) is categorized based on the size of the particles. Each category of particulate matter has distinct sources, health implications, and regulatory challenges, making it essential for air quality management strategies to address the specific characteristics and risks associated with PM1, PM2.5, and PM10. There is strong evidence for the negative health impacts associated with exposure to this pollutant. The major components of PM are sulfates, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. |
PM1 | PM1 particles are those with a diameter of 1 micrometer or smaller. These ultrafine particles are capable of penetrating the deepest areas of the lungs and entering the bloodstream, due to their extremely small size. | The health implications of PM1 are profound as they can affect the cardiovascular system, respiratory health, and even cognitive functions. The ability of these particles to travel long distances and their persistence in the environment increase their potential health impacts. |
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PM2.5 | PM2.5 refers to particulate matter with a diameter of 2.5 micrometers or smaller. These fine particles can penetrate the lung barrier and enter the alveoli, the tiny sacs within our lungs. | PM2.5 is associated with several health risks, including chronic respiratory conditions, heart diseases, and premature death. Due to their ability to remain suspended in the air longer than heavier particles, they can affect more people and penetrate indoor environments more effectively. |
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PM10 | PM10 particles include those with a diameter of 10 micrometers or smaller. These particles are small enough to be inhaled but larger than PM2.5 particles. | PM10 can cause adverse health effects by reaching the upper airways and the bronchi. Chronic exposure to PM10 has been linked to respiratory and cardiovascular diseases, as well as reduced lung function and increased rates of chronic bronchitis. |
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| Oxides of Nitrogen (NOx) | Concentrations of nitrogen dioxide in the air. | Impacts respiratory health and contributes to acid rain. | NO2 is a gas that is commonly released from the combustion of fuels in the transportation and industrial sectors. |
| Carbon monoxide (CO) | Concentrations of CO in the air. | Health concern and indicator of incomplete combustion. | CO is a colourless, odourless and tasteless toxic gas produced by the incomplete combustion of carbonaceous fuels such as wood, petrol, charcoal, natural gas and kerosene. |
| Ground-Level Ozone (O3) | Levels of ozone near the Earth's surface. | Impacts respiratory health and ecosystem damage. | Ozone at ground level – not to be confused with the ozone layer in the upper atmosphere – is one of the major constituents of photochemical smog and it is formed through the reaction with gases in the presence of sunlight. |
| Sulfur dioxide (SO2) | Concentrations of sulfur dioxide in the atmosphere. | Impacts respiratory health and contributes to acid rain. | SO2 is a colourless gas with a sharp odour. It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores that contain sulfur. |
| Ammonia (NH3) | Ammonia emissions from agricultural activities, industrial processes, and vehicle sources. | Plays a role in fine particulate matter (PM2.5) formation and carries environmental and health implications. | |
| Chlorofluorocarbons (CFCs) | Synthetic compounds formerly used in refrigeration and aerosol propellants, known for their role in ozone layer depletion. | Although their production has been regulated, they may still be present in the atmosphere. | |
| Polycyclic Aromatic Hydrocarbons (PAHs) | Organic compounds, consisting of multiple fused aromatic rings, produced during incomplete combustion, including the burning of fossil fuels, tobacco and wood. | PAHs can be released into the air through processes like vehicle exhaust, industrial emissions, and burning of organic matter. Some PAHs are known to be carcinogenic. | |
| Persistent Organic Pollutants (POPs) | Organic compounds that resist degradation and can persist in the environment for extended periods. | Examples include certain pesticides and industrial chemicals and can have long-term environmental impacts. | |
| Volatile Organic Compounds (VOCs) | Levels of organic chemicals that can evaporate into the air and contribute to ground-level ozone formation. These include a wide range of organic chemicals like benzene, toluene, and xylene. | Precursors to ground-level ozone and potential health hazards. | |
| Heavy Metals - Lead (Pb) | Lead emissions into the atmosphere. | Adversely affects human health, particularly the nervous system. Emitted from various sources, including industrial processes and leaded gasoline. | |
| Heavy Metals - Mercury (Hg) | Mercury release into the atmosphere, from both natural and industrial sources. | Mercury can accumulate in ecosystems and pose health risks, especially when converted into methylmercury, a highly toxic form. |
