AIR QUALITY ISSUES, Who Cares ?

Air pollution is the human introduction into the atmosphere of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the environment. Air pollution causes deaths and respiratory disease. Air pollution is often identified with major stationary sources, but the greatest source of emissions is mobile sources, mainly automobiles. Gases such as carbon dioxide, which contribute to global warming, have recently gained recognition as pollutants by climate scientists, while they also recognize that carbon dioxide is essential for plant life through photosynthesis. The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems. Actualy primary pollutant are release in a harmful form. Secondary pollutant, by contrast, become hazadous after reaction in the air. Photochemical oxidants which is compound created by reaction driven by solar energy and atmospheric acids are probably the most important secondary pollutant. Fugitive or nonpoint source, emission are those that do not go through a smokestack. By far most massive examples of this category is dust fri]om soil erosion, strip mining, rock crushing and building construction. Leaking valves and pipe joints contributes as much as 90 percent of the hydrocarbons and volatile organic chemicals emitted from oil refines and chemial plants.

CATEGORIES OF AIR POLLUTANT

Pollutants can be classified as either primary or secondary. Usually, primary pollutants (major Pollutant) are substances directly emitted from a process, such as from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories.The examples for primary pollutant is sulfur dioxide, Nitrogen Oxides, Carbon monoxide, Particulate material, Volatile organic compound, Lead and other toxic compound. Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog. Sometimes pollutants may be both primary and secondary that is, they are both emitted directly and formed from other primary pollutants. In this part we will explain more details about major pollutant which Primary Pollutant.

MAJOR POLLUTANT

Sulfur Dioxides , is a colourless, corrosive that damages both plants animals. Once in atmosphere, it can be further oxidized to sulfur trioxide

which is react with water vapor or dissolves in water droplets to form Sulfuric Acid

a major component of acid rain. Sulfur Dioxides and Sulfate ions are probably second only to smoking as cause of air pollutant related health damage. Sulfate Particles and droplets also reduce visibility in the United States by as much as 80 percent.

Nitrogen Oxides

are highly reactive gases formed when combustion initiates reaction between atmospheric nitrogen and oxygen. The initial product nitric oxide, oxidized further in the atmosphere to nitrogen dioxides, a reddish brown gas that gives photochemical smog its distinctive colour. This is because these gas convert readily from one form to the other. The general term

is used to describe these gases. Nitrogen oxides combine with water to form nitric acid (

which is also a mojor component of acid precitipation. Excess Nitrogen in water is causing eutrophication of inland waters and coastal seas. It may also encourage the growth of weedy species that crowd out native plant.

Carbon Monoxide (CO) is less common than the principal form of atmospheric carbon, carbon dioxide (

), but more dangerous , CO is a colorless, odourless but highly toxic gas produced mainly by incomplete combustion of fuel (coal, oil, charcoal, wood or gas ). CO inhibits respiration in animals by binding irreversibly to hemoglobin. In the United States, two thirds of the CO emission are created by internal combustion engines in transportation. Land clearing fires and cooking fires also are major sources. About 90 percent of the CO in the air is consumed in photochemical reaction that produce ozone

Particulate materials includes dust, ash, soot, lint, smoke, pollen, spores, algal cell, and many other suspended materials. Aerosol or extremely minute particles or liquid droplets suspended in the air, are icluded in this class. Particulates often are the most apparent form of air pollution, since they reduce visibility and leave dirty deposits on windows, painted surfaces, and textils. Breathable particles smaller than 2.5 micro are among the most dangerous of this group because they can damage lung tissues. Asbestos fibers and cigarette smoke are among the most dangerous respirable particles in urban and indoor air because they are carcinongenic.

Volatile Organic compound (VOCs) are organic gases. Plants, bogs, and termittes are the largest sources of VOCs especially isoprenes (

),terpenes (

) and Methane (

). These volatile hydrocarbon are generally oxidized to CO and

in the atmosphere. More dangerous synthetic organic chemical such as benzene, toluene, formaldehyde, vinyl chloride, phenol, chlroform and trichloroethylene, are release by human activities.Principles sources are incompetely burned fuel from vehicles, power plants, chemical plants and petroleum refineries. These chemical play an important role in the formation of photochemical oxidants.

Photochemical oxidants are product of secondary atmospheric reaction driven by solar energy. One of the most important of these reaction involves formation of singlet atomic oxygen by splitting nitrogen dioxide. This atomic oxygen react with another molecule of (

) to make ozone (

). Although ozone is important in the stratosphere in ambient air it is highly reactive and damage vegetation, animal tissues and buildings materials. Ozone acrid biting odor is a distinctive characteristic of photochemical smog.

Toxic metal and halogens are chemical elements that are toxic when concentrated and released in the enviroment. Principles metals of concern are lead, mercury, arsenic, nickel, beryllium, cadmium, thallium, uranium, cesium , and plutonium. Halogens which is fluorine chlorine, bromine and iodinevare highlly reactive toxic elements. Most of these materials are mined and used in fuels, especially coal. Lead and mercury are widespreads neurotoxins that damage the nervous system. By some estimate, 20 percent of all innercity children suffer some degree of development retardation from high enviromental lead level. Long range transport of lead and merury throung the air is causing bioaccumulation in remote aquatic ecosystems such as arctic lakes and seas. Chlorine is a toxic halogen widely used in bleach, plastics and others products Methyl bromide a powerful fungicide used in agriculture and chlorofluorocarbon are also implicated in ozone Depletion.

AIR POLLUTION INDEX (API)

The Air Quality Index (AQI) is a standardized indicator of the air quality in a given location. It measures mainly ground-level ozone and particulates (except the pollen count), but may also include sulfur dioxide, and nitrogen dioxide. Various agencies around the world measure such indices, though definitions may change between places. The United States Environmental Protection Agency (EPA) and the Meteorological Service of Canada (MSC) differ on what AQI structure and health classification is used:

Health classifications used by the EPA:

• 
  
• 0-50 Good is usually green
  
• 51-100 Moderate is usually yellow
  
• 101-150 Unhealthy for sensitive groups is usually orange
  
• 151-200 Unhealthy is usually red
  
• 201-300 Very unhealthy is usually purple
  
• 301-500 Hazardous is usually maroon
  

The EPA's AQI 100 corresponds to 0.08 ppm ozone, and to other levels for other pollutants. Source: EPA. The AQI standards in Canada are relatively more stringent. The current health classifications used by the Meteorological Service of Canada (MSC) are as follows:

• 
  
• 0-25*: Good (green)
  
• 26*-50: Fair (yellow)
  
• 51-100: Poor (orange)
  
• 101+: Very poor (red)
  

The air quality in Malaysia is reported as the API or Air Pollution Index. Four of the index's pollutant components (i.e., carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide) are reported in ppmv but PM10 particulate matter is reported in μg/m³. Unlike the American AQI, the index number can exceed 500. Above 500, a state of emergency is declared in the reporting area. Usually, this means that non-essential government services are suspended, and all ports in the affected area closed. There may also be a prohibition on private sector commercial and industrial activities in the reporting area excluding the food sector.

API

Air Pollution
Level

Health Implications

0 - 25

Low

None expected.

26 - 50

Medium