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Air pollutants

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Air pollution is caused by the emission to the atmosphere of certain substances which, alone or through chemical reaction, can damage human health and the environment.

The single pollutants causing most damage to ecosystems, human health and materials are nitrogen oxides (NOx), sulphur dioxide (SO2), ammonia (NH3), ground level ozone and airborne fine dust, known as particulate matter (PM).

Particulate matter: Is the general term used to describe solid particles and liquid droplets found in the air. “Primary” particles are those released directly to the atmosphere, these include dust from roads and black and/or elemental carbon from combustion sources. In general, coarse PM is composed largely of primary particles. “Secondary” particles, on the other hand, are formed in the atmosphere from chemical reactions involving primary gaseous emissions. Thus, these particles can form at locations distant from the sources that release the precursor gases. Examples include sulfates formed from sulfur dioxide emissions from power plants and industrial facilities and nitrates formed from nitrogen oxides released from power plants, mobile sources, and other combustion sources. PM10 refers to particulates with a diameter of less than 10 micrometers, comprising the ‘coarse’ fraction. PM2.5 refers to those with a diameter of less than 2.5 micrometers, comprising the ‘fine’ fraction. Fine particulates are strongly correlated with harmful effects on human health as they can penetrate into sensitive areas of the lungs. There is insufficient evidence to determine a safe level of human exposure to particulates and in practical terms all increases in PM levels should be regarded as harmful.

Ground-level ozone: This secondary pollutant is formed when NOx and volatile organic compounds (VOCs) react chemically in the presence of sunlight, making it most prevalent in summer and in high temperature regions. In contrast to the ozone layer in the stratosphere which protects us from harmful ultraviolet radiation, ozone at ground level is harmful both to human health and ecosystems. Human exposure to ozone is associated with chest tightness, coughing, wheezing, non-fatal effects on lung functions as well as acute mortality. Regarding the environment, ozone damage is the most serious regional air pollution problem affecting forests, vegetation and agricultural crops.

Ammonia (NH3): Most ammonia is produced by animal waste decomposition, rubbish and fertilisers for plants that produce a high concentration level of nitrates in surface water. In an industrial level, textile manufacturing process, plastics, explosives, paper, drinks and food, cleaning products, coolers and other industrial products.  At lower concentrations might cause coughing and nose and throat irritation. A higher exposure may cause scorches in skin, eyes, throat and lungs; in extreme scenarios, blindness, permanent lung damage or even death.

Nitrogen oxides (NOx): These comprise the gases nitric oxide (NO) and nitrogen dioxide (NO2). NO is formed predominantly in high temperature combustion processes and can subsequently be converted to NO2 in the atmosphere. NOx contribute to acid deposition, eutrophication, the formation of ground-level ozone, smog and human health impacts.

Sulphur dioxide (SO2): This gas is formed from the combustion of fuels containing sulphur, such as coal and oil. Sulphur dioxide contributes to acid deposition and harms human health. During the oxidation stage in the atmosphere, this gas produce sulfates, salts that might be carried by course particles (PM10) and with the humidity they will form acids. These acids are a huge percentage of the fine particles (PM2.5). The SO2 is hygroscopic, this means that the substance reacts with the water molecules from the surrounding environment to produce sulfuric acid and sulphurous acid, components of the acid rain. SO2 is related with cardiovascular issues, asthma, chronic bronchitis, affecting children and older adults in a higher proportion. Regarding the environment, sulphur oxides and sulfuric acid are correlated with the permanent damage of vegetation, soil degradation, construction materials and watercourses.

Volatile organic compounds (VOCs): Volatile carbon-based chemical compounds are emitted to the atmosphere from natural sources and from human activities, such as the use of solvents, paints and varnishes, the storage of transport fuels and their use at filling stations, and car exhaust emissions. VOCs are a key component in the formation of ground-level ozone.

DSC_1856_3Using NIHON KASETSU air quality sensors AirQ series, together with eComo03 Monitoring System, it’s possible to monitor and control the air pollution in the cities as well as in any industrial or construction area.

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