POLLUTION & ITS MANAGEMENT | AIR & NOISE POLLUTION [CSEC HSB]

SYLLABUS REFERENCE 

• [E1] identify pollutants in the environment;
• [E2] discuss the causes of … air pollution; 
• [E3] describe the effects of pollutants on human beings and the environment; 
• [E4] explain the methods of controlling pollution; 

Pollutant

Any substance or energy produced by human activity, that may cause harm in the environment. 

Pollutants are not only chemicals such as oil and fertilizers. They can also be heat released from power stations, as well as noise from industrial and domestic sources. 

Pollution 

Contamination of the environment by substances and activities which have harmful or toxic effects. 

Apart from some natural events such as volcanic eruptions, human activity is the dominant contributor to pollution. 

Sources of Pollutants 

• Domestic 
• Agricultural 
• Industrial, including:
• thermal pollution 
• heavy metals 
• combustion products 
• oil (petroleum) 
• Transport (cars, ships & planes) 
• combustion of fuel for road transport produces sulphur dioxide, nitrogen oxides, carbon monoxide, carbon dioxide & hydrocarbons 
• brake linings on some aging vehicles are a source of pollutants such as asbestos. 

Human Activities that Cause Pollution 

All of these activities and their impact are connected to the human population explosion and modern lifestyles, which includes urbanisation. 

• Resource extraction 
• Manufacture of goods 
• Production of waste 

Social & Economic Effects of Pollution 

Our modern lifestyle - with its demands for food, goods, and travel - provides jobs, improving the income and quality of life of individuals and benefitting the wider economy. However, the modern lifestyle creates pollution in the following ways: 

• Processed food and modern household appliances are produced in factories, creating organic and chemical waste 
• We require farms to produce more and more food, using fertilisers and pesticides 
• Homes and industry consume power, often generated using fossil fuels 
• The desire to move around quickly has led to a rapid rise in the number of cars on the roads 
• Goods need to be transported and international travel is commonplace, all largely powered by combustion 
• Increasing numbers of humans produce more and more waste. 

The amount of pollution we generate affects people's health and wellbeing. The following are several examples of the social and economic effects of pollution: 

• Air pollution leads to respiratory diseases, which may result in people having days off work or being less productive when they are at work. This has an impact on household incomes and the economy as a whole. 
• Many chemical pollutants cause diseases such as cancer, or birth defects, incurring personal and societal medical costs. 
• Pollution can also affect mental health. Living in towns close to noisy industrial plants can be a source of distress, particularly if it causes lack or sleep or disturbed sleep patterns. 
• When beautiful environments become polluted, people who depend on tourism can lose their incomes. Whole economies can be affected. 
• Marine pollution in the Caribbean threatens the 'Blue Economy' - the fisheries, tourism and transport - which depends on the ocean. 
• Flooding as a result of refuse in water courses threatens homes, farms and other businesses. 

Control of Pollution 

Generally, pollution is controlled by taking steps to find alternative processes that either:

• do not release pollutants 
• capturing the pollutants before they reach the environment. 

AIR POLLUTION 

Air pollutants generally comes from factories, oil-fuelled power plants, and domestic fires. 

Particle pollution by windblown sand from Africa (Sahara dust) is a common natural pollution in the Caribbean. 

These pollutants can be broken up into two categories:

Pollutants Near the Ground 

These have a direct effect on the environment & on humans. 

Dust, Dirt, Exhaust Fumes, and Smoke 

These leave deposits on buildings and plants. On plants, the deposits lead to reduced photosynthesis, which eventually kills the plants. 

Health Effects

• Inhaled particles accumulate in the alveoli. 
• There, it produces diseases such as silicosis, leading to shortness of breath & difficulty breathing after exercise 
• Infection may lead to bronchitis, which involves a persistent cough & can be fatal. 
• Cases of asthma are more frequent where air pollution occurs 
• Windblown asbestos is very dangerous because it gets trapped in the lungs, causing asbestosis, which induces a severe type of cancer. 

Prevention / Mitigation 

In some countries, only smokeless fuels may be burned. Factories in such countries are also not permitted to release smoke into the air. 

Sulphur Dioxide (SO₃) and Nitrogen Oxides (NOₓ) 

Sulphur dioxide corrodes metal, eats into stonework, and damages the leaves of plants. 

These chemicals dissolve in the water vapour/droplets in the atmosphere to form sulphuric & nitric acid. Some carbonic acid is also formed when carbon dioxide dissolves in water in the atmosphere. These fall back to the surface as acid rain. 

The acidity (pH) of rainwater has been shown to increase in industrial areas. 

Nearby natural spaces can also be affected, since these pollutants can be carried by wind and clouds to areas some distance away. There are whole forests dying due to exposure to acid rain caused by pollutants from far away urban and industrial areas. 

Impact of Acid Rain 

It damages stone and metal. 

In the soil, it reacts with mineral nutrients, displacing essential and other poisonous minerals, leading to them being washed out and released from the soil. Toxic soluble aluminium ions are released into the soil in this way, where it is taken up by plants and damages the roots. The aluminium travels down the food chain, damaging plant and animal life along the way.  

It acidifies ponds, lakes, & rivers. The acidification kills much of the animal life that depends on these water bodies. 

Solutions 

• Some coal-fired power stations produce large quantities of sulphur dioxide. Some of them are using processes to remove it from the waste gases before they are released into the air. 
• Some governments have passed lawsy restricting the output of sulphur dioxide and nitrogen oxides from various sources. 
• Many countries are moving away from combustion-based power production to renewable sources such as solar, wind, wave, and hydro (water). 

Lead & Other Heavy Metals 

Lead is a heavy metal which is toxic to the nervous system. It can be carried long distances by the wind. 

Quite low concentrations in the body can cause brain damage, leading to memory & learning difficulties, shakes, and hallucinations. It is particularly dangerous to young children because of their developing nervous system. 

It is not excreted by the body. It accumulates in tissues such as bones. This means that high levels of lead may occur in the body, even though only a low level is found in the environment. 

Car exhaust as a source has been greatly reduced, since lead-free petrol is now used in most countries of the world. Other sources are usually not air-based:

• water that has passed through lead pipes 
• particles from roofing materials, some pesticides and old paint. The chemical can enter the body via ingestion. 
• fish that have been living in water that is contaminated by industrial waste and pesticides containing lead. Poisoning occur by eating the fish. 

Smog 

This occurs when water vapour and chemicals trapped in still air reduce visibility. There are two kinds of smog:

Reducing Smog: These are produced by smoke and high concentrations of sulphur dioxide, which comes from the burning of petroleum-based fuels such as coal and petrol. Exposure to this kind of smog increases deaths from lung diseases in a population. 

Photochemical Smog: These are common in valleys where temperature inversions occur. It is produced via the action of sunlight on pollutants, particularly from car exhausts, such as nitrogen oxides and complex carbon compounds. The sunlight induces various chemical reactions that produces ozone (O₃) and other complex compounds. These chemicals then form a thick blanket-like smog over towns and cities.

Effects

• Smog irritates the eyes and also damages young plants. 
• It screens out sunlight at street level, and makes it difficult to see. 
• The ozone produced causes asthma, eats into rubber, textiles etc. It also damages the leaves so that they lose minerals, turn yellow and are susceptible to disease. 

Solutions

Cars can be fitted with catalytic converters. They remove the oxides of nitrogen and carbon compounds from exhaust gases. 

Carbon monoxide (CO)

This is an invisible, odorless gas that comes from car exhaust fumes. It can also be produced by incomplete burning of gas in faulty boiler or heaters in homes. 

It combines irreversibly with haemoglobin in the blood to form carboxyhaemoglobin. This reduces the oxygen-carrying capacity of the haemoglobin, leading to unconsciousness and death. 

It is normally quickly dispersed in fresh air. However, in a confined space, it can reach dangerous concentrations. In very busy cities and heavy traffic, CO levels can get dangerously high near the road surface. 

Solution 

Modern cars have catalytic converters to remove carbon monoxide. 

Pollutants in the Upper Atmosphere 

Gases such as CO₂ and other greenhouse gases in the upper atmosphere prevent infrared (IR) radiation from being reflected to outer space. This adds to the greenhouse effect and is thus called the enhanced greenhouse effect. 

Other greenhouse gases: water vapour, methane, and ozone. 

The result is global warming, which may lead to a rise in sea levels, as well as to unpredictable & intensified weather patterns. 

Most scientists now accept that human influence is the major cause of climate change. The main contributor has been the increase in carbon dioxide in the atmosphere, due to the following:

• burning of fossil fuels by motor vehicles and industry 
• accidental and deliberate burning of forests. Apart from adding carbon dioxide into the atmosphere, it also removes the trees that would have continued to absorb carbon dioxide for photosynthesis. 
• burning of solid waste, such as in large scale incinerators. 

Solutions 

Most countries require plants to reduce the output of pollutants, especially carbon dioxide, by using alternative energy sources. However, implementing many of these strategies are technically difficult and costly. 

NOISE POLLUTION 

Noise is unwanted sound that is created by humans. Therefore it is considered a pollutant. 

Noise from roads, aircraft, heavy machinery, bars, clubs, and parties are pollutants in that context.  

Solution 

Development of quieter machines and noise abatement laws, which limit volume and timing of noise.