Air pollution

Introduction

Air pollution, whether occurring indoors or outdoors, refers to the contamination of the air through physical, biological, or chemical alterations in the atmosphere. It ensues when harmful gases, dust, or smoke enter the air, posing a threat to the well-being of plants, animals, and humans as the air becomes polluted. The accumulation of detrimental gases and substances in the atmosphere, reaching concentrations that endanger human health or cause measured effects on living matter and materials, constitutes air pollution. Major sources include power and heat generation, the incineration of solid wastes, industrial processes, and, notably, transportation. The six primary types of pollutants are carbon monoxide, hydrocarbons, nitrogen oxides, particulates, sulfur dioxide, and photochemical oxidants.

An increase in any of the constituents of the atmosphere which is harmful to the living beings and their environment, is known as air pollution.” (World Health Organization)

Sources of air pollution

1. Burning of fossil fuels, such as coal, petroleum, and other industrial combustibles, which emit sulfur dioxide and contribute significantly to air pollution. Additionally, vehicular emissions from trucks, cars, trains, and airplanes are substantial contributors to air pollution.

2. Agricultural activities: Ammonia being a common byproduct from such practices, posing a significant hazard in the atmosphere. The use of insecticides, pesticides, and fertilizers in agriculture releases harmful chemicals into the air.

3. Exhaust emissions: Factories and industries release large quantities of carbon monoxide, hydrocarbons, organic compounds, and other chemicals, thereby depleting the overall air quality.

4. Mining operations: It involve the extraction of minerals from below the Earth’s surface using large equipment, releasing dust and chemicals into the air during the process.

5. Indoor air pollution: It is caused by household cleaning products, as well as the combustion of coal, wood, or oil, serving as significant sources of smoke, dust, and pollutants such as sulfur dioxide and nitrogen oxides.

6. Tobacco smoke: A direct and significant source of air pollution that adversely affects health. Even non-smokers may inhale the smoke produced by others.

Air pollutants

Air pollutants include:

-Carbon Monoxide:

• Colorless and odorless
• Produced when carbon does not burn completely in fossil fuels
• Found in car exhaust
• Deprives the body of oxygen, leading to headaches, fatigue, and impaired vision

– Sulfur Dioxide:

• Produced when coal and fuel oil are burned
• Present in power plant exhaust
• Narrows the airways, causing wheezing and shortness of breath, particularly in individuals with asthma.

-Nitrogen Dioxide:

• Nitrogen Dioxide is a reddish-brown gas.
• It is produced when nitric oxide combines with oxygen in the atmosphere.
• Present in car exhaust and power plants.
• Affects the lungs and causes wheezing, increasing the chance of respiratory infection.

-Lead:

• Lead is produced from the combustion of leaded petrol.
• Mining and smelting of lead ores create pollution.
• Hematological and neurological effects of lead occur more frequently in children than in adults.

Particulate Matter:

• Particulate Matter consists of particles of different sizes and structures released into the atmosphere.
• It is present in various sources, including fossil fuels, dust, smoke, fog, etc.
• Can accumulate in the respiratory system, aggravating heart and lung diseases and increasing the risk of respiratory infection.

-Ground-Level Ozone:

• At the upper level, ozone shields the Earth from the sun’s harmful UV rays.
• At ground level, ozone becomes a harmful pollutant.
• It is formed from car, power, and chemical plant exhaust.
• Ground-level ozone can irritate the respiratory system and exacerbate asthma, reducing lung function by inflaming and damaging the lining of the lungs.

-Carbon Dioxide:

• Carbon dioxide is generated through the combustion process using coal, oil, and gas.
• It does not participate in any significant chemical reactions with other substances in the air.

Air Quality Index

The Air Quality Index (AQI) categorizes different levels of health concern as follows:

“Good” AQI (0 to 50): Air quality is considered satisfactory, and air pollution poses little or no risk.

“Moderate” AQI (51 to 100): Air quality is acceptable; however, for some pollutants, there may be a moderate health concern for a very small number of people. For example, individuals who are unusually sensitive to ozone may experience respiratory symptoms.

“Unhealthy for sensitive groups” AQI (101 to 150): Although the general public is not likely to be significantly affected in this AQI range, people with lung disease, older adults, and children are at a greater risk from exposure to ozone. Meanwhile, individuals with heart and lung disease, older adults, and children are at a higher risk due to the presence of particles in the air.

“Unhealthy” AQI (151 to 200): Everyone may begin to experience some adverse health effects, and members of sensitive groups may experience more serious effects.

“Very Unhealthy” AQI (201 to 300): This level triggers a health alert, signifying that everyone may experience more serious health effects.

“Hazardous” AQI (greater than 300): This level triggers health warnings of emergency conditions. The entire population is more likely to be affected.

Effects of air pollution

Effects of air pollution on health can be categorized into immediate and delayed effects:

Immediate Effects:

• Immediate effects are borne by the respiratory system, leading to conditions such as pneumonia and acute bronchitis.
• In cases of intense pollution, it may result in immediate death by suffocation.

Delayed Effects:

• Delayed effects include chronic bronchitis, lung cancer, bronchial asthma, emphysema, and respiratory allergies.

Lead, a component of air pollution, poses significant risks to various body systems and is particularly hazardous to the developing brain and nervous system in children. Elevated lead levels in children have been associated with impaired neuropsychological development, including loss of IQ, poor school performance, and behavioral difficulties.

Social and economic aspects:

Air pollution has significant social and economic consequences, including:

• Destruction of plant and animal life.
• Corrosion of metals.
• Damage to buildings.
• Costs associated with cleaning, maintenance, repairs, and aesthetic nuisance.
• Reduced visibility in urban areas.
• Soil degradation and damage to clothing.

Prevention and control of air pollution

Prevention and control of air pollution involve various strategies:

a. Containment: This involves preventing the escape of toxic substances into the ambient air. Containment can be achieved through various engineering methods such as enclosure, ventilation, and air cleaning. A significant contribution in this field is the development of “arresters” designed for the removal of contaminants.

b. Replacement: This strategy involves replacing technological processes that cause air pollution with new processes that do not contribute to pollution. For example, increased utilization of electricity, natural gas, and central heating in place of coal has significantly contributed to the reduction of smoke.

c. Dilution: Dilution is a viable strategy as long as it remains within the self-cleaning capacity of the environment. For example, certain air pollutants can be naturally removed by vegetation. The establishment of “green belts” between industrial and residential areas is an attempt at dilution.

d. Legislation: Air pollution is controlled in many countries through appropriate legislation, such as Clean Air Acts. Legislation covers matters such as the height of chimneys and grants local authorities the power to conduct investigations, research, and education related to air pollution.

e. International Action: To address air pollution on a global scale, the World Health Organization (WHO) has established an international network of laboratories for monitoring and studying air pollution. These centers issue warnings of air pollution where and when necessary.

f. Education of people: In Nepal, many households use wood, charcoal, and coal as domestic fuel for cooking and other purposes, contributing to air pollution. Tobacco smoking not only affects the smoker’s health but also significantly influences the surrounding atmosphere, producing smoke that contributes to air pollution. Therefore, educating people about the use of smokeless stoves and the hazards of tobacco smoking is an essential step in reducing pollution.

g. Location of industries and residential areas: Efforts should be made to locate industrial plants on the outskirts of towns and cities to avoid nuisances from smoke, gases, dust, and odors. In new housing developments, residential areas should be planned away from industrial complexes to minimize the impact of air pollution on residents.

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