Particulate matter-an alarming source of air pollution

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Particulate matter refers to the finely divided solid and liquid particles of organic or inorganic nature that remains suspended

in the atmosphere. Particulate matter can be of different size, composition, and origin, consisting of pollen, mold spores,

house dust mites, bacteria, acids, viruses, dust particles, cement dust, fine clay particles containing heavy metals, fly ash, oil

smoke, smog, tobacco smoke and soot. Particulate matter (PM) can be divided into different groups ranging from few

nanometers to micrometers but dominated size ranging from 2.5 to 10 µm (PM 10-2.5 ). Due to fine size and great reactivity PM 2.5

is considered more precarious. Particulate matter has two prime sources of its production. 1) Particulate matter contributed

by natural processes (dust storms, digestion processes, radioactive decay of earth, wildfires and volcanic eruption). These

natural processes mostly ensue in open areas, forests and mountains that insitu generate particulate matter in gignatic

quantity and may be transported to some conjusted areas as well by the air movement and other sources. 2) Particulate

matter that enamates due to the anthropogenic activities is major contributor in poisoning the fresh air gradually all over

the world. The major anthropogenic activities induclude mushroom growh of industries, unplanned urbanization,

substandard manufaturing techniques and unethical use of transport.

Urban air has become festered due to the high quantity of nitrate, elemental carbon, zinc, arsenic, cadmium and lead (mostly

part of the fine clay) during the tire friction of vehicles on the roads as traffic has increased up to the alarming situation. The

used tyres are burnt in brick kilns the suburbs of the big cities and particulate matter containg pollutants are being released

in the air in the form of ash or fine particles. Different industries like pharmaceutical, chemical and metallurgical are

contributing carbonaceous aerosols, metals, sulphate, organic carbon, ammonium, chloride and sodium that become seated

on the raective clay particles. Noxious air of urban and rural areas is the result of diversified elemental particles released

during construction of buildings and houses. The farm lands fresh air is also getting lethal due to emission of volatile

compounds (methane, ethylene), dust, liquid vapors and other toxins by different agricultural practices. Among these

practices, tillage operations like ploughing, use of heavy machinery and sowing of seeds are dominated to add PM containing

dust particles and different toxic compounds adsorbed on these particles in air and being transported with air. Variety of

pesticides, insecticides and herbicides are sprayed on the plants and soils which contribute PM either in the form of droplets

or soil particles containing toxic agricultural chemicals. This material not only cause insitu air pollution but also transported

far of places with air and increased the contaminated area to miles away from the origin.

Particulate Matter is playing its role in global warming and ozone depletion creating serious concerns to the environment of

the whole world. Ozone is continuously depleting in the troposhere by the presence of reactive species of choloflorocarbon,

nitrogen oxide and halons in the particulate matter. As particulate matter contain gun holders for ozone like chlorine

sourced from choloflorocarbon, PM containing CFC react with ozone layer in the presence of the light and breakdown of

ozone (O 3 ) stimulate entry of detrimental UV radiation towards earth. Stone work of modern age buildings get deteriorated

due weathering process carriedout by the PM containg acids, oils, smoke and soot. Finishes of vehicles and motors become

whacked due to the complex composition of the particulate matter. Particulate matter in the form of the dust particles

become filled up in the rivers and water bodies lowering their water holding capacity. Visibility is due to the light that

reaches to the observers eye but due to the particulate matter pollution scattering of light occurs and things become blurr

to observor.

The solid particles in PM consisting of very fine clay or dust particles are very reactive and act as adsorption seats for various

toxic ionized species of inorganic and organic compounds. During inhaling the air these toxic particles (PM 2.5 µm) get entry

into the body, desorb in different fluids like blood circulatory system of humans and move along with blood stream causing

lung cancer, liver cancer, kidney failure, skin disorders and cardiovascular diseases. The PM of different size and composition

potentially carry pollens, viruses and bacteria also facilitating their entry into respiratory track causing severe damage to

vital organs in humans. The variety and extent of diseases in the environment are directly proportional to the chemistry and

extent of particulate matter in air causing human mortality and morbidity at alarming rate. Exposure of particular matter to

animals causes malfunctioning of the normal metabolism. Ultra-fine titanium dioxide sourced from tanneries causes severe

damages to pulmonary organs of animals inhaling contaminated air. Plant growth and production also drastically affected

when particulate matter deposits on the leaves and stems and slow down the process of photosynthesis and respiration by

clogging their stomata.

The sustainability of our future depends that how quickly and effectively we get control on the harmful effects of PM which

has emerged as a major air pollutant. In this regard urgent need is to cut short the use of private vehicles replacing with good

quality public transport to reduce smoke and other toxic gasses poduced during incomplete combustion. Scrubbers must be

ensured in the industries particularly in metallurgical industry and chemical industries to neutralise their waste product

before entering into environment. Agricultural awareness must be created in the farmer community to restrict wildfires of

the agriculture residues and alternative technology should be introduced. The department of urban planning and

development should constitute laws and policies for the distruction and construction of builings. Already existing laws and

policies must be implimented with out differentiating between a house hold industries to giant industrialists. Proper

inspection and maintenance of the industrial treatment plants must be ensured. Trees, natural purifiers of the air, should be

planted at pilot scale in the green belts of the big cities and along the main roads to ensure healthy breath for all the living

organism. We are the custodians of heathy and pure air for our upcoming generations to memorize us with good character.


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