What are the major outdoor air pollutants?
Major Outdoor Air Pollutants
Carbon monoxides:
Carbon monoxide (CO) is one of the major outdoor air pollutants. It is a colorless, odorless, and highly toxic gas that forms during the incomplete combustion of carbon-containing materials.
Major source: Major sources are motor vehicle exhaust, burning of forests and grasslands, tobacco smoke, and open fires and inefficient stoves used for cooking.
Health effects: CO reacts with hemoglobin in red blood cells and reduces the ability of blood to transport oxygen to body cells and tissues. Chronic exposure to CO can trigger heart attacks and aggravate lung diseases such as asthma and emphysema. CO can also cause headache, nausea, drowsiness, mental impairment, collapse, coma, and death.
Carbon dioxide:
CO2 is also a colorless and odorless gas. About 93% of the CO2 in the atmosphere is the result of the natural carbon cycle and the rest comes from human activities.
Source: Comes mostly from burning fossil fuels and clearing CO2-absorbing forests and grasslands. Industrial revolution is another major source.
Effects: Increasing levels of CO2 from human activities are contributing to global warming and climate change. High levels of CO2 in the air causes respiration problem.
Nitrogen oxides and nitric acid:
Nitric oxide (NO) is a colorless gas that is produced by the reaction of nitrogen and oxygen gas in air at the high-combustion temperatures in automobile engines and coal-burning plants. NO is also generated from the Nitrogen cycle by the combination of lightning and certain soil bacteria. NO reacts with oxygen in the air to form nitrogen dioxide (NO2) which is a reddish-brown gas. NO and NO2 are collectively called nitrogen oxides (NOx). Some of the NO2 reacts with water vapor (H2O) in the air to form nitric acid (HNO3) and nitrate salts (NO3). These gases play a role in the formation of photochemical smog, greenhouse gas.
Effects: Nitrogen oxides will irritate the eyes, nose, and throat; irritate respiratory organ ailments like respiratory illness and bronchitis; and increase status to metabolism infections by impairing the system. they’ll conjointly suppress plant growth and cut back visibility once they are converted to acid and nitrate salts.
Sulfur dioxide and sulfuric acid:
Like CO2 and NO, Sulfur dioxide (SO2) could be a colorless gas with an irritating odor. Concerning third of the SO2 within the atmosphere comes from natural sources as a part of the sulfur cycle. The rest simple fraction comes from human sources, principally combustion of sulfur-containing coal in power and industrial plants and oil refinement and smelting of compound ores. within the atmosphere, SO2 is converted to aerosols, that are microscopic suspended droplets of sulfuric acid (H2SO4) and suspended particles of salt (SO42-) that come back to the earth as an element of acid deposition.
Effects: pollutant, acid droplets, and salt particles decrease visibility and irritate respiration issues. SO2 and H2SO4 will injure crops, trees, soils, and aquatic life in lakes. They additionally corrode metals and damage paint, paper, leather, and stone on buildings and statues.
Particulates:
Suspended particulate matter (SPM) consists of a spread of solid particles and liquid droplets small and light enough to stay suspended within the air for long periods. Almost sixty two percent (62%) of the SPM in outside air comes from natural sources like mud, wild fires, and ocean salt. The remaining thirty eighth comes from human sources like coal-burning power and industrial plants, motorized vehicles, plowed fields, building, unpaved roads, and tobacco smoke. The most harmful types of SPM are fine particles (PM-10, with a median diameter of less than 10 micrometers) and ultrafine particles (PM-2.5, with a median diameter of less than 2.5 micrometers).
Effects: These particles will irritate the nose and throat, harm the lungs, irritate bronchial asthma and respiratory disorder, and shorten life. poisonous particulates, like lead, cadmium, and polychlorinated biphenyls will cause mutations, fruitful issues, and cancer. Particulates additionally reduce visibility, corrode metals, and discolor garments and paints.
Ozone:
O3 is a colorless and extremely reactive gas that could be a major part of photochemical smog.
Effects: It will cause coughing and respiration problems, worsen respiratory organ and heart diseases, reduce resistance to colds and respiratory illness (pneumonia), and irritate the eyes, nose, and throat. It conjointly damages plants, rubber in tires, fabrics, and paints.
Ozone within the layer close to ground level is commonly observed as “bad” ozone, whereas the ozone in the stratosphere layer is considered as “good” ozone that protects us from harmful ultraviolet light radiation. However, human activities are reducing the amount of good ozone within the layer and increasing the number of harmful unhealthy gas (bad ozone) within the layer close to ground level—especially in some urban areas.
Volatile organic compounds (VOCs):
Organic compounds that exist as gases within the atmosphere are referred to as volatile organic compounds (VOCs). Most are hydrocarbons, like isoprene (C3H8) and terpenes like C10H15 emitted by the leaves of many plants, and alkane series methane (CH4), a greenhouse gas. Almost a third of the world’s CH4 emissions come from natural sources, largely plants, wetlands, and termites. The remainder comes from human sources, primarily rice paddies, landfills, oil and fossil fuel wells, and cows (mostly from their belching). Benzene (C6H6) is found in automobile and power plant emissions and tobacco smoke.
Effects: long-run exposure to benzene will cause leukemia, varied blood disorders, and immune system injury. Short exposure to high levels will cause dizziness, state of mind, and death.
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