4 Environmental health
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- Unit 8: Air quality
- Unit 9: Water and sanitation
- Unit 10: Climate change and health
Unit 8: Air quality
When you have completed this unit you should be able to:
- Describe common sources of air pollution.
- Describe the health problems associated with air pollution.
- List strategies to reduce both indoor and outdoor air pollution.
8-1 What are the major sources of air pollution?
Some major sources of outdoor air pollution are:
- Vehicle emissions such as car, truck and bus exhausts. There is growing concern about diesel fuel and its contribution to air pollution. There is strict regulation of the use of diesel engines in Europe and North America, but in low- and middle-income countries, there is widespread use of “dirty” diesel with high levels of sulphur.
- Burning fossil fuels such as coal in power stations.
- Cooking fires in some communities, especially wood fires.
The major source of indoor air pollution is smoke from cooking fires. Cigarette smoke can also pollute the air, particularly in overcrowded homes.
8-2 What is particulate matter and what damage does it cause?
Particulate matter is a mixture of very small particles of dust, water droplets and several other chemicals, suspended in air. Particulate matter is a result of burning fossil fuels or wood and is seen as smoke or haze. It is a very important part of air pollution. If the particles are small enough, they penetrate deep into the lungs and cause inflammatory changes. Very small particles may even enter the circulation and cause damage in organs other than the lungs. Particulate matter can cause many diseases, including cardiovascular disease, chronic obstructive lung disease (emphysema and chronic bronchitis) and lung cancer.
Small particle air pollution can cause serious lung disease, such as cancer, as well as disease in other organs.
8-3 How big a problem is air pollution?
Air quality in South Africa is mostly good, except in some large cities. Worldwide, poor air quality is a major cause of ill health, particularly in rapidly developing countries such as China and India. The World Health Organisation’s Global Burden of Disease study puts air pollution 4th on the list of health risks, behind high blood pressure, poor diet and smoking.
Globally, air pollution is thought to be the 4th most important health risk.
8-4 What are the chemical air pollutants that have an effect on health?
Several chemical air pollutants have an effect on health and it is likely that there are some we do not know about. The important ones include:
- Ozone: The small amount of ozone that naturally occurs in the atmosphere is a good thing as it protects us against ultraviolet rays in sunlight. However large amounts of “ground ozone” produced by the action of sunlight on the emissions from some industries and vehicle exhausts can cause breathing and lung problems.
- Sulphur dioxide: Sulphur dioxide has a very sharp smell. It is most commonly found as an emission from coal-fired power stations. It is also found in diesel fuel. Fortunately modern vehicles now use lower sulphur fuel. Sulphur dioxide causes breathing problems, particularly in children. It combines with water to form acid rain and contributes to forest degradation.
- Nitrogen dioxide: Nitrogen dioxide is produced by engines burning fossil fuels, particularly vehicles that burn diesel fuel. It also causes respiratory problems and contributes to acid rain and ozone. There was a scandal in Europe and North America in 2015 when it emerged that some car manufacturers were cheating diesel emission tests. It is now known that most diesel vehicles, including modern engines, produce unacceptably high levels of nitrogen dioxide.
Ozone, sulphur dioxide and nitrogen dioxide are important chemical pollutants in the atmosphere.
8-5 How can air pollution be reduced?
Most air pollution is a result of industry and mass road transport and is outside the control of individuals. Although there have been some successes stories where communities have been able to improve air quality locally, the control of industrial and vehicle emissions requires legislation, regulation and monitoring by national and local governments. Unfortunately, regulation of emissions in low- and middle-income countries is often weak.
In future the use of electric vehicles should help reduce outdoor air pollution due to the use of fossil fuels. In South Africa the introduction of electric trains has replaced many coal and diesel burning trains.
- In 2016, a non- governmental organisation reported that European traders were exporting diesel too dirty for use in Europe to West Africa. As a result, 5 West African countries have introduced strict new regulations to control fuel standards and vehicle emissions.
There are however things that individuals and communities can do to reduce their smoke exposure:
- A major source of smoke exposure in many low- and middle-income countries is the use of indoor fires. Increasing access to cleaner fuels such as electricity, gas and paraffin is likely to reduce the risks from indoor smoke. Solar cookers are becoming increasingly available in communities that previously used coal or wood as fuel.
- Many of us can also control our use of fossil fuels for transport (e.g. petrol or diesel) by sharing lifts, using public transport, walking and supporting the movement for bicycle safety. It is also important to turn engines off rather than leaving them idling when vehicles are stationary.
- Having cigarette smoke-free public areas, and encouraging people not to smoke in the house. Indoor smoking regulations in South Africa are strict, except in private homes and cars.
Unit 9: Water and sanitation
By the end of this unit you should be able to:
- State the water requirements of humans.
- Explain the health impacts of reduced access to good quality water.
- Describe the difference between improved and non-improved toilets.
- List the hazards of non-improved and shared toilets.
- Explain why there are concerns about water and sanitation services in the future.
9-1 How good is access to water in South Africa?
South Africa is a water scarce country, with about half the global average of rainfall. This means that the supply of good quality water is an issue for everybody, and that water should not be wasted. The 2016 General Household and Community surveys reported that nearly 90% of households in South Africa now have access to piped water but only 63% believe their water safe to drink. Water borne diseases remain common, with about 20% of deaths in South African children under 5 still due to diarrhoea.
Water related health problems can result from limited access to a sufficient quantity of water, or to poor quality water. Therefore access to good quality water remains a challenge in many areas
Many homes in South Africa still have poor quality water.
9-2 What are the water requirements for a human?
- Human adults require about 3 litres of water per day in order to survive.
- In addition to drinking water a minimum of 3 to 6 litres per day is required for cooking, washing and basic sanitation. Requirements go up steeply when flush toilets are used.
- People are considered at high risk of disease if they have access to less than 20 litres per person per day and low risk if they have access to over 100 litres per person per day.
- The South African government defines a basic water service as 25 litres of good quality drinking water per day per person, from a source within 200 m of the household.
- In high-income communities in water rich countries, water access may be over 400 litres per person per day.
In South Africa, the basic daily requirement of good quality water is 25 litres per person.
- During the 2016-2018 drought in Cape Town the aim was 50 litres per person per day for drinking, cooking, washing (showering) and flush toilets. Recycling water was strongly encouraged, especially for flushing toilets.
9-3 How do health problems result from an insufficient quantity of water?
Health problems from shortage of water are:
- Dehydration. Water requirements are increased in hot weather. Older people may have a reduced sensation of thirst. This means that dehydration can lead to death in the elderly during heat waves.
- Reduced food supply. Water is necessary for agriculture and raising livestock. Lack of water means reduced food supply often with increased prices of food.
- Illness from being unable to maintain personal hygiene.
The main danger from too little water is dehydration.
9-4 How are health problems caused by poor quality water?
Illness can be a result of drinking contaminated water:
- Water can be contaminated with microbes causing acute disease:
- Bacteria such as E Coli, typhoid or cholera
- Viruses such as polio, hepatitis or rotavirus
- Protozoa such as amoebae and giardia
- Contamination with microbes can also result in a chronic condition called “environmental enteropathy”.
- Water can be contaminated with poisonous chemicals. Toxic chemicals can leach out from containers and pipes used to store or deliver water. Important examples include bisphenol A, which is used in the plastic industry, and the lead used in older pipes.
In addition, there can be disease causing agents living in or on water. For example, mosquitoes living in stagnant water may be vectors for diseases such as malaria, dengue and zika virus.
The main danger from poor quality water is infection.
9-5 What is environmental enteropathy?
In the past, health teams have been very aware of the risk of acute diarrhoea from contaminated water. It is now known that children drinking contaminated water are also at risk of a chronic condition called “environmental enteropathy”. In this condition, there is a change in the types of bacteria living in the gut (the “microbiome”). This results in chronic inflammation of the gut and thinning of the gut lining (atrophy of the villi). As a result, food is poorly absorbed (malabsorption). Therefore environmental enteropathy may be an important contributor to undernutrition and growth stunting in poorer communities. It also limits the effectiveness of nutrition supplementation programmes and oral immunisations.
Environmental enteropathy is a chronic gut condition caused by drinking contaminated water.
9-6 What are the main chemical risks to water safety in countries like South Africa?
The main risks are:
- In South Africa and many other low and middle-income countries, gold mining is a major source of water contamination with heavy metals such as mercury and arsenic. This toxic waste may be released directly into natural water bodies such as rivers when the industry is unregulated. The toxic waste may also be stored in dams, but major spills are not uncommon. There is currently great concern over “acid mine drainage” from disused deep-shaft mines around Johannesburg. When mines are no longer worked, the high water table in this region means that shafts fill with water that becomes contaminated with heavy metals and sulphuric acid. This toxic water, which has a characteristic yellow-orange colour (sometimes called “yellow boy”) contaminates surface water.
- Textile, pulp and paper industries are major polluters, releasing caustics, chlorine and detergents into water.
- Commercial farming can lead to water pollution when insecticides, herbicides and fungicides are washed into natural water bodies. Fertiliser can also cause algal blooms (overgrowth of algae) that use the dissolved oxygen in the water which kills other water life such as fish.
Mining, industries and farming can all cause chemical contamination of water.
9-7 Why is sanitation important?
Two factors make access to toilets important:
- Proper toilet facilities are important to protect drinking water from being contaminated by human faeces.
- Privacy and dignity. Access to decent toilets has been a major political issue over the past few years.
9-8 What are “improved toilet facilities” and what proportion of South African households have access to them?
Improved toilet facilities consist of flush toilets and ventilated improved pit toilets (latrines):
- Flush toilets: They require a reliable water supply and must also have a certain water flow through the system to stop them blocking up. There are many reports of shared flush toilets being unmaintained and in an unhygienic state.
- Ventilated improved pit (VIP) toilets: The VIP toilet has a ventilation pipe designed to keep away smells and flies. They need either emptying or proper covering while a new one is built. The contents become harmless compost after a while. VIPs can be a very acceptable option, especially in rural areas, but fell out of favour when the Department of Water Affairs made a commitment to flush toilets. Recently VIP toilets have been provided in many rural areas.
About 60% of the population have access to flush toilets while a further 18% have access to VIP toilets. This gives a total of 78% with access to improved toilet facilities. In future it may no longer be possible to use high quality drinking water to flush toilets in water scarce parts of South Africa.
Only 60% of the South African population has access to flush toilets.
9-9 What are “unimproved toilet facilities” and what percentage of South African households have access to them?
Unimproved toilet facilities are less acceptable options:
- Unventilated pit toilets: These can be less pleasant than VIPs, but are still quite common.
- Bucket system: In this system, human waste is collected in a household bucket which is then emptied at the nearest convenient location. It is not only unpleasant for household members, but the waste poses a health risk.
- No toilet facility: This is unacceptable as people have to use “the bush”.
Unventilated pit toilets are used by 17% and the bucket system by 1% of the population. No toilet facilities are available for a further 4%. Therefore a total of 22% of the population have unimproved or no toilet facilities.
About 22% of South Africans have no access to improved toilets.
9-10 How many households in South Africa share toilet facilities?
Currently 16% to 20% of households in South Africa share toilet facilities with other households.
9-11 What are the other concerns around toilets?
Common concerns are:
- Nearly 80% of the population of South Africa now has access to improved toilet facilities but sanitary facilities are said to be deteriorating in a number of municipalities because of a lack of maintenance, water supply or pit emptying services.
- About 25% of households using shared facilities report that the toilet facility is unhygienic or poorly lit.
- A further issue is safety, particularly for women, when the toilet is a distance from their household.
- All pit toilets must be properly protected as children fall into them.
9-12 Are there challenges with water and sanitation infrastructure?
Yes. There are a number of concerns:
- The water and sanitation infrastructure in South Africa is quite old and requires maintenance.
- The number of people moving into towns and cities is increasing, placing a strain on municipal water and sanitation services.
- If climate change leads to weather cycles with longer dry periods, water shortages will become common while the earth movements associated with drying and cracking are likely to damage the infrastructure further.
- Only about 25% of South Africa’s sewage treatment plants are reported to be up to standard.
There is concern about the future of both water and sanitation infrastructure in South Africa.
There are many concerns about meeting the water and sanitation needs in the future.
Unit 10: Climate change and health
By the end of this unit you should be able to:
- Explain how the use of fossil fuels is leading to climate change.
- Describe the changing risks to global health from climate change.
- Describe the strategies for reducing the rate and the risks from climate change.
10-1 What is the main cause of climate change?
Heat from the sun warms the planet and then is reflected back from the earth into space. Gases in the atmosphere, such as carbon dioxide and methane keep some of this heat trapped in the atmosphere and prevent it escaping into outer space. This is a good thing otherwise the planet would be much colder. These gases are called “greenhouse gases” because they provide the same function as the glass in a greenhouse which keeps the heat in.
Carbon is widely found in living things and for about 350 million years, the carbon in plants and small marine animals has been trapped and compressed in the rock, forming “fossils fuels” that we know as oil, coal and natural gas. Since the Industrial Revolution, humans have been burning more and more fossil fuels and the trapped carbon has been released into the air as carbon dioxide. As a result there has been a rapid build-up of greenhouse gases over the past few decades, which means that more of the sun’s heat is kept in the atmosphere and not allowed to escape. The result is excessive global warming leading to climate change.
Global warming is caused by the excessive burning of fossil fuels and results in climate change.
10-2 What will be the result of climate change?
There are 2 main results of climate change:
- Scientists predict that climate change will result in more severe weather events such as droughts, floods, heat waves and massive storms with climate change most areas of the world will get hotter and drier but others will get colder and wetter. This is due to changing weather patterns as a result of warmer oceans. This is why the term “climate change” is generally preferred to “global warming”.
- Climate change not only consists of rising air temperatures but also leads to rising sea levels due to the melting of ice, especially in the north and south poles. This will cause flooding in many cities along the coast or on low lying islands or river deltas. These changes are likely to get much worse over the next 100 years.
Trying to predict what will happen to the weather over the next 100 years is not an exact science. There are those people who deny that serious climate change is a real danger. However, the majority of scientists agree that climate change is happening and is probably the greatest threat to public health in this century, and that it is caused by humans burning increasing amounts of fossil fuels. Climate change is likely to increase the gap in health and wellbeing between rich and poor countries in the next few decades. It should not be ignored in the hope that it will not happen.
Climate change is leading to rising sea levels.
- It is predicted that the western regions of South Africa will become drier while the eastern regions will become wetter. These changes in weather patterns are already becoming obvious with drought in Cape Town and floods in Johannesburg and Durban.
10-3 What are the risks to health from climate change?
It is likely that the greatest challenges and risks from climate change will be in low and middle-income countries. Health risks include:
- Heat related illnesses: Heat waves can lead to heat stroke and dehydration, particularly in children, the elderly, and people with cardiovascular disease and obesity.
- Extreme weather events: Storms with strong winds and heavy rain can cause direct injury, damage to buildings, mudslides and flooding. Flooding can lead to waterborne disease and crop failure. Most sewage systems also collect storm water, so extreme rainfall can overwhelm sewage systems leading to the leakage of untreated sewage into the environment.
- Drought and increased water stress: Unusually long periods without rainfall means that water shortages will occur and crops are more likely to fail. Providing enough water for drinking and flush toilets will be a challenge. Extreme cycles of soil drying and rain causes earth movement that can crack pipes and damage water and sewage infrastructure.
- Increased concentration of air pollutants: Heat waves are often associated with stagnant air that increases the concentration of air pollutants such as smog in cities.
- Changes in the distribution of “climate sensitive” infectious diseases: Climate change will alter the range of disease vectors such as mosquitoes and ticks. Some animal borne diseases will also change distribution if change in the habitat of a disease-carrying animal brings them closer to human settlements. For example plague carried by fleas on rats.
- Food insecurity: Crop failures and reduced livestock productivity are more likely as a result of these weather events.
- Conflict: A scarcity of critical resources, particularly water and food, is likely to lead to conflict.
Climate change is a major threat to health especially in low- and middle-income countries.
10-4 What can be done?
Reading about climate change and the likely consequences can be frightening. There are 2 main strategies for reducing the risk:
- Reducing the severity of climate change by reducing carbon lost into the atmosphere: A serious reduction in global carbon emissions requires national clean energy policies. We can make our concerns known to politicians if we have the opportunity. On an individual level, we can all reduce our use of fossil fuels by using technologies such as solar water geysers and solar panels to generate electricity and by avoiding unnecessary use of motor vehicles. Hospitals and healthcare facilities are big users of energy. It is important to reduce energy use where possible (such as turning off air conditioners and lights in offices after the working day) and to build energy conservation into new facilities. It is possible to increase the use of “green energy” such as wind, solar and hydro-electric power generation.
- Reducing the consequences of climate change: Being aware of the risks from climate change means that we can take steps to reduce them. We can plan for efficient water use and increased water storage; we can plant trees in cities and protect green spaces to reduce heat increases, and we can have early warning systems and management plans for extreme weather events and emerging climate sensitive diseases.
Increasing the use of wind, solar and hydro-electric energy can reduce the need for fossil fuels.
- South Africa has started a programme dedicated to increasing the use of renewable energy. Generating cheap home-based or town-based “green energy” (wind and solar) on a large scale throughout the country in both urban and rural areas avoids energy loss in long power transmission lines from large central generating stations and promises to reduce greenhouse gasses and improve air quality.
10-5 Why are the consequences of climate change likely to be worse in low- and middle-income countries?
- It is thought that temperature rises will be more extreme around the equator where many low- and middle-income countries are situated.
- In low- and middle-income countries, people are more concerned about present problems than planning for climate change in the future, so strategies to reduce the consequences of climate change are less likely to be successfully implemented than in high-income countries.
- Climate change will increase the population of cities as a result of water stress and pressure on rural livelihoods. Cities tend to be warmer than rural areas so there is a greater potential for heat related illness and the pressures on water and sanitation are likely to be intensified in crowded cities. Among the biggest concerns is the future in African megacities such as Lagos, Kinshasa and Cairo, but there are already serious problems with water shortages for the poor in South Asian cities.
- Many low lying areas in river deltas in poor countries like Bangladesh and Egypt will be flooded by sea levels rising.
Low- and middle-income countries are also least likely to be prepared and able to manage climate change.
The countries and communities most likely to be affected by climate change are also the least likely to be prepared for it.