Health Hazards of Air Pollution
The World Health Organization (WHO) states that 2.4 million people die each year from causes directly related to air pollution, and 1.5 million of these deaths are caused by indoor sources. One study has shown a strong correlation between pneumonia-related deaths and air pollution caused by motor vehicles. Worldwide, there are more deaths linked to air pollution per year than to car accidents. Research by WHO also shows that the greatest concentration of particulate matter particles exists in countries with high poverty and population rates, such as Egypt, Sudan, Mongolia, and Indonesia.
Direct causes of air-pollution related deaths include aggravated asthma, bronchitis, emphysema, lung and heart diseases, and respiratory allergies. The U.S. Environmental Protection Agency (EPA) estimates that a set of proposed changes in technology of diesel engines could result each year in the U.S. in 12,000 fewer mortalities, 15,000 fewer heart attacks, 6,000 fewer visits to the emergency room by children with asthma, and 8,900 fewer respiratory-related admissions to the hospital.
Health effects caused by air pollution may range from subtle physiological and biochemical changes to difficulties in breathing, wheezing, coughing, and aggravation of existing cardiac and respiratory conditions. These conditions can result in increased use of medications, visits to the doctor or emergency room, more admissions to the hospital, and premature deaths. Individual reactions to air pollution depends on the type of pollutant, the degree of exposure, and the individual’s medical condition.
Certain respiratory conditions can be made worse in people who live closer or in large metropolitan areas. In one study, it was found that such patients had higher levels of pollutants in their system because of more emissions in the larger cities. In patients with the disease, cystic fibrosis, patients already born with decreased lung function, had worse lung function as a result of such pollutants as smoke emissions from automobiles, tobacco smoke, and improper use of indoor heating devices. Some studies have shown that patients in urban areas suffer lower levels of lung function and more chronic bronchitis and emphysema.
Because children are outdoors more they are more susceptible to the dangers of air pollution. Children living within cities with high exposure to air pollutants are at risk to develop asthma, pneumonia and other lower respiratory infections.
In addition to respiratory and heart-related ailments, air pollution can also cause an increase in cancer, eye problems, and other conditions. For example, use of certain agricultural herbicides and pesticides, such as DDT (an organic pesticide) and PCBs (poly-chlorinated biphenyls), use of some industrial solvents and plastics, radioactive waste, use of some indoor materials like asbestos, and ozone depletion can all cause cancer.
Smog, caused by coal burning, and ground-level ozone produced by motor vehicle exhaust can cause eye irritation, as well as respiratory problems, and ozone depletion can cause an increased incidence of cataracts. Carbon monoxide from motor vehicle exhaust and from faulty vents and chimneys and charcoal burning indoors can cause poisoning and fatalities. Mercury released from coal-fired power plants and from medical waste can cause neurotoxicity (poisoning to nerve tissue).
Protecting Yourself from Air Pollution
After reading the above sections, you may be confused as to where the air is healthier, outdoors or indoors? While it is not always possible to know what exact steps you should take under any situation, common sense often plays a role. For example, if you hear in the news that the outdoor air quality is particularly bad, then it might make sense to either wear masks outdoors or to stay indoors as much as possible at such times, especially if you already have such respiratory conditions as asthma, for example. Because you have more control over your indoor air quality than the outdoor air quality, there are some simple steps you can take indoors to make sure the air quality is less polluted.
Perhaps you could review the section, “Pollution of Indoor Air” above, and come up with some ideas for how you could reduce indoor air pollution. For example, make sure your house is well ventilated and there is circulation of air. Try to avoid use of toxic substances in the home; always read labels to see what warnings about toxic ingredients are listed. If you are not sure about a particular product, use either outdoors or in a well-ventilated room and avoid direct inhalation. Use of medical supply masks is also helpful to protect yourself further.
Make sure that vents, chimneys, and vents are working properly and never burn charcoal indoors. Carbon monoxide detectors can be placed in the home, if carbon monoxide emission is of concern. In addition, keeping your home as clean as possible from pet dander, dust, dist mites, and mold, and making sure air conditioning systems are working properly can minimize effects on asthma and other respiratory problems. Are there any other ways you can think of to protect yourself from air pollution?
Lesson Summary
Outdoor air pollution consists of either chemical, physical, or biological agents that modify the natural characteristics of the atmosphere and cause unwanted changes to the environment and to human health.
There are two kinds of pollutants: primary and secondary pollutants.
There are many sources of human-caused air pollution, the most common being the burning of fossil fuels.
Outdoor air pollutants cause many environmental effects, among them global warming, global dimming, and ozone depletion.
Indoor air pollutants are either chemical or biological in nature.
Both outdoor and indoor pollutants cause many health problems, ranging from respiratory and cardiac to cancer, eye problems, and poisoning.
While it is not always possible to protect yourself from poor air quality outdoors, there are a number of measures you can take to protect yourself from poor indoor air quality.
Review Questions
Define outdoor air pollution.
Most air pollutants can be traced to the burning of fossil fuels. What were the sources of such pollutants before the Industrial Revolution?
Why does deforestation contribute to an increase in global warming?
Explain why one of the environmental effects of global dimming may result in less food at all trophic levels.
Name two environmental effects of ozone depletion.
There is no direct evidence linking ozone depletion to a higher incidence of skin cancer in human beings. Give an explanation for this.
Further Reading / Supplemental Links
Unabridged Dictionary, Second Edition, Random House, New York, 1998.
http://www.epa.gov/acidrain/education/site_students/
http://www.koshlandscience.org/exhibitgcc/index.jsp
Vocabulary
acid rain
Precipitation or deposits with a low (acidic) pH.
aerosols
Airborne solid particles or liquid droplets.
air
The mixture of gases present in the atmosphere.
anthropogenic
Human-based causes.
atmosphere
A layer of gases that surrounds the planet; composed of five layers.
global dimming
A reduction in the amount of radiation reaching the Earth’s surface.
global warming
The recent increase in the Earth’s temperature.
greenhouse effect
The atmosphere’s trapping of heat energy radiated from the Earth’s surface.
greenhouse gases
The cause of global warming by certain gases via the greenhouse effect.
outdoor air pollution
Chemical, physical, or biological agents that modify the natural characteristics of the atmosphere and cause unwanted changes to the environment and to human health.
ozone depletion
Reduction in the stratospheric concentration of ozone.
ozone hole
A seasonal decline of ozone over Antarctica.
primary pollutants
Substances released directly into the atmosphere by processe
s such as fire or combustion of fossil fuels.
secondary pollutants
Substances formed when primary pollutants interact with sunlight, air, or each other.
Points to Consider
One of the effects of outdoor air pollution is to cause global warming. Global warming, in turn, has an effect on both land and sea. Think about how the effects of global warming on the amount and pattern of precipitation will have an effect on water pollution.
Environmental effects of global dimming include less energy to drive evaporation and the hydrologic cycle, and cooler ocean temperatures, which may lead to changes in rainfall and drought. Will such changes affect water pollution?
Some outdoor air pollutants have a direct effect on aquatic habitats. For example, acid rain can adversely affect freshwater habitats.
Lesson 25.2: Water Pollution and Waste
Lesson Objectives
Describe water pollution sources.
Explain how water pollution affects living organisms.
Discuss how to prevent water pollution.
Discuss ways you can save water.
Check your Understanding
Water pollution obviously has to do with water.
What are water resources?
What is the demand for water?
What are the sources of fresh water?
Answers
Surface water is water found in rivers, lakes, or freshwater wetlands. It is naturally replenished by precipitation and naturally lost through discharge to evaporation, discharge to the oceans, and sub-surface (groundwater) seepage.
Groundwater is the water flowing within aquifers (a geological formation that contains or conducts groundwater, especially for supplying water for wells, etc.). The natural input to groundwater is seepage from surface water and the natural outputs are to springs and seepage to bodies of water.
Desalination is an artificial process by which saline water (usually sea water) is converted to fresh water. Only a very small amount of total water use is supplied by desalination.
Frozen water found in icebergs has not been found to be a reliable water source. Glacier runoff is a source for surface water.
Introduction
While water may seem limitless and everywhere – after all, you can turn your faucet and out it comes, without appearing to dry up – in fact, in the United States it is a limited resource, and in many parts of the world, even scarce. Add to this the necessity of having water without pollution and you can see that unpolluted water is even harder to find (Figure below).
Figure 25.8
Water pollution can cause harmful effects to ecology and human health.
Water pollution is the contamination of water bodies by contaminants, mostly anthropogenic, and causing a harmful effect on living organisms. As you explore in this lesson how water pollution affects living things, you will see the urgency in preventing water pollution and discover ways to save water. Perhaps you will be inspired to think of how your household, community, and even world can be a model to others to not take clean water for granted!
Sources of Water Pollution
Although natural phenomena such as storms, algal blooms, volcanoes, and earthquakes can cause major changes in water quality, human-caused contaminants have a much greater impact on the quality of the water supply. Water is considered polluted either when it does not support a human use (like clean drinking water) or undergoes a major change in its ability to support the ecological communities it serves.
The primary sources of water pollution can be grouped into two categories, depending on the point of origin:
B. Nonpoint source pollution refers to contamination that does not originate from a single point source, but is often a cumulative effect of small amounts of contaminants (such as nutrients, toxins, or wastes) gathered from a large area. Examples of this include runoff in rainwater of soil, fertilizers (nutrients) or pesticides from an agricultural field, soil from forested areas that have been logged, toxins or waste from construction or mining sites, and even fertilizers or pesticides from your own backyard!
A. Point source pollution refers to contaminants that enter a waterway or water body through a single site. Examples of this includes discharge (also called effluent) of either untreated sewage or wastewater from a sewage treatment plant, industrial effluent, leaking underground tanks, or any other discrete sources of nutrients, toxins, or waste.
Specific contaminants causing water pollution include a wide variety of chemicals, and pathogens (disease-causing substances). While many of the chemicals and substances that are regulated may be occurring naturally (iron, manganese, etc.) it is often the concentration of the substance that determines what is a natural component of water and what is a contaminant.
In addition to toxic substances and disease-causing ones, alteration of water’s physical chemistry, including acidity, electrical conductivity, and temperature, can also have an effect.
Effects of Water Pollution on Living Things
Water pollutants can have an effect on both the ecology of aquatic ecosystems as well as on human health. Let’s examine several types of pollution problems and how they affect both the ecology and human health.
Polution Problem: Eutrophication
Definition: An increase in chemical nutrients, specifically compounds containing nitrogen or phosphorus, in an ecosystem.
Causes: Frequently a result of nutrient pollution such as the release of sewage effluent and run-off from lawn fertilizers into natural waters, such as rivers or coastal waters.
Effect on Ecology: Excessive growth of aquatic vegetation or phytoplankton (or algal bloom and decay, and a lack of oxygen, the latter causing severe reductions in water quality, fish, and shellfish.
Effect on Human Health and Well-Being:
Decreases the resource value of rivers, lakes, and estuaries to adversely affect recreation, fishing, hunting, and aesthetic enjoyment.
If nitrogen is leached into groundwater, drinking water can be affected because nitrogen concentrations are not filtered out.
Biotoxins created during algal blooms are taken up by shellfish, such as mussels or oysters; if humans eat these shellfish, then shellfish poisoning can occur and you can become extremely sick, including paralysis and other neurological conditions.
Polution Problem: Ocean Acidification
Definition: A process whereby the oceans’ uptake of anthropogenic carbon dioxide from the atmosphere causes an ongoing decrease in pH of the oceans (see “Points to Consider,” Lesson 25.1: Air Pollution, showing a possible link of air pollutants to water pollution).
Causes: Human actions such as land-use changes and the combustion of fossil fuels can lead to an increase in carbon dioxide into the atmosphere, some of which is then absorbed by the oceans
Effect on Ecology:Decrease in pH primarily affects oceanic calcifying organisms, such as corals and shellfish; may also directly affect reproduction or other physiology of marine organisms or indirectly cause negative impacts through their food resources
Effect on Human Health and Well-Being: No likely effects
Polution Problem: Transformation of Chemicals
Definition: Transformation of many chemicals, including chlorinated hydrocarbons (carcinogens), especially over long periods of time in groundwater.
Causes: Chemicals are used in industrial metal degreasing and electronics manufacturing and find their way into the groundwater or other waterways.
Effect on Ecology: As they undergo change in groundwater, can lead to new hazardous chemicals.
Effect on Human Health and Well-Being: Such contaminated groundwater can poison drinking water and lead to various human health problems, including cancer.
Polution Problem: Aquatic Debris
Definition: Aquatic debris (or trash) in fresh and saltwater waterways.
Causes: Shipping accidents, Landfill erosion, or dumping of trash.
Effect on Ecology: Aquatic wildlife swallowing plastic bags, stra
ngulation by plastic six-pack rings, entanglement of wildlife in nets (Figure below).
Effect on Human Health and Well-Being: Adversely affects recreation and aesthetic enjoyment.
Figure 25.9
Lake Valencia, Venezuela, showing vivid green algal blooms, resulting from continued influx of untreated wastewater from surrounding urban, agricultural, and industrial land uses. This contributes to ongoing eutrophication, contamination, and salinization of the lake This pollution impacts the lakes use as a reservoir for the surrounding urban centers and limits opportunities for tourism and recreational uses as well.
Figure 25.10
Marine debris can adversely impact all sorts of aquatic life. Pictured here is a marine turtle entangled in a net.
Figure 25.11
Intercepting nonpoint pollution between the source and waterway has been found to be successful. Pictured here, a bioretention cell, or rain garden, in the U.S, is designed to treat polluted storm water runoff from an adjacent parking lot.
Let’s close this section and look at a few other effects of water pollution on human health. According to the World Health Organization (WHO), diarrheal disease is responsible for the deaths of 1.8 million people every year. It was estimated that 88% of that burden is attributed to unsafe water supply, sanitation, and hygiene, and is mostly concentrated in the children of developing countries.
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