Effects of Environmental Contaminants – Air and Soil Pollution

1. Effects of Environmental Contaminants – Air and Soil Pollution • pollutants can also be called contaminants: waste from human activities that may harm humans or other forms of life when released into the environment. • the most common environmental factors that affect human health include: air pollution, ultraviolet rays, heat, noise pollution, soil and water pollution, heavy metals, workplace chemicals, and pathogens.

2. Air Pollution And Related Contaminants • There are five major air pollutants that result from human activities and are dangerous to human health. • These are: carbon monoxide (CO), sulphur dioxide (SO2), oxides of nitrogen (NOx), particulate matter, and hydrocarbons. • Air pollutants have caused other environmental factors that affect human health, including global warming (heat), as well as more ultraviolet radiation from the sun penetrating Earth’s atmosphere.

3. Carbon monoxide • Carbon monoxide is a clear, odourless gas, the result of incomplete combustion of organic materials when there is insufficient oxygen available, often in an enclosed space. • Carbon monoxide is a product of burning gasoline within internal combustion engines, wood stoves, propane heaters, and lawn mowers • CO is also released into the air when people smoke, and from using spray paint, degreasers, and paint removers • Carbon monoxide is sometimes released indoors by accident when fuel-burning appliances like furnaces, stoves, generators, and fireplaces are not working properly and venting to outside air. It can quickly build up indoors and harm humans.

4. Sulphur dioxide • Sulphur dioxide results from burning fuels that contain sulphur. • All organisms contain sulphur, so burning fossil fuels like coal and oil release sulphur into the air, bonded to oxygen. • volcanoes also release SO2 into the air. • more than 90% of SO2 emissions in North America come from human activity. • Unlike carbon monoxide, SO2 has an unpleasant smell; it can combine with different chemicals in the air to form harmful contaminants, such as sulphuric acid, a component of acid precipitation.

5. Oxides of nitrogen • Oxides of nitrogen are formed when oxygen reacts with nitrogen at high temperatures. • Almost all NOx comes from burning fossil fuels in automobile engines and at power generating stations. • Smoking cigarettes also releases NOx, as do unvented gas stoves and kerosene heaters. • Like SO2, NOx can react with different chemicals in the air to form other contaminants.

6. Particulate Matter • Particulate matter results from many human activities. • Outside air can contain: ash from factory smokestacks; smoke from forest fires; and manure, soil, and fertilizer particles from farming. • Indoors, air can be polluted by fibreglass particles from insulation in buildings, as well as concrete and wood dust during construction.

7. Particulate matter is irritating to the skin and respiratory system. Other air pollutants attach to particulate matter in the air and react with each other to form harmful contaminants For example, SO2 and NOx combine with other chemicals on particulate matter to become sulphuric acid (H2SO4) and nitric acid (HNO3) respectively. acid precipitation can make lake waters too acidic to support aquatic life. It can also react with limestone to form gypsum, which washes away with rain, so that limestone buildings and monuments are damaged.

8. Hydrocarbons And Photochemical Smog • Hydrocarbons are combinations of hydrogen and carbon that evaporate from fuel supplies like gasoline, or result from left-over fuels that have only partially burned. • They do not cause major health effectsin humans on their own unless they combine with other pollutants. • For example, ultraviolet radiation from the sun helps hydrocarbons to combine with NOx to produce photochemical smog which has ozone (O3) and nitrates in it. Ozone destroys plants and can injure human lungs, while nitrates in photochemical smog irritate the eyes. • Large cities surrounded by mountains suffer the most from photochemical smog because the mountains can prevent winds from blowing the smog away. • L.A. and Mexico City are infamous for smog, and Calgary experiences smoggy conditions when the wind from the west is not dispersing airborne pollutants.

9. Ultraviolet Radiation • Ultraviolet radiation is a form of electromagnetic radiation which travels through space in waves • UV rays have a wavelength of about 100–400 nm and are therefore more energetic than visible light (400–780 nm). • There is so much energy in UV rays that it can cause cell damage and deformities in living things. • There are three types of UV rays: UVA, UVB, and UVC; UVC has the most energy, and is the most dangerous, while UVA is the least energetic.

10. Ozone Depletion • The stratospheric ozone layer filters out 99% of UV rays from the sun. • However, Earth’s ozone layer is being depleted by chlorofluorocarbons (CFCs) released from human-built mechanisms like refrigerators and air conditioners. • The chlorine in CFCs breaks ozone, allowing more UV rays to reach Earth’s surface. • CFCs are no longer being used in most appliances, however the CFCs that are already in the air will continue to erode the ozone layer for years until they eventually break down. • Chlorofluorocarbons also belong to a group of air pollutants called greenhouse gases (GHGs) that are causing global warming.

11. GHGs and Climate Change • Increasingly, heat is becoming a dangerous environmental factor. • As Earth’s climate warms up, the number and strength of hurricanes and other storms becomes greater. • Extreme summertime heat waves are becoming common; for example, during the summer of 2003, Europe experienced a long period of intensely hot weather which not only caused a drought in southern Europe, but over 30,000 people died because of the heat. • Global warming is drastically reducing the amount of sea ice in the arctic. • Ice reflects the sun’s heat back into the atmosphere, while open water tends to absorb heat •  with more open water and less ice at the poles, Earth will retain more heat from the sun. • Polar bears need sea ice to hunt seals and other aquatic prey; they are just one of many polar species that will probably not survive global warming.

12. Sound Pollution (Noise) • Noise pollution is any sound that is unwanted. • It may seem odd to think of noise as a pollutant, but excessive sound can be harmful because sound exerts pressure on our ears. • The pressure of sound is measured in decibels (dB) and also by pitch or frequency (dBA). • Hearing loss begins when a person is exposed for 8 hours or more to sounds above 78 dBA. • the figure above describes different sound sources and their intensity in dB.

13. Workplace Chemicals • Workplace chemicals include herbicides, volatile organic compounds (VOCs), and multi-purpose solvents like chemical degreasers, paint thinners, and dryers that have uses in such applications as cementing, leather tanning, and printing. • When these chemicals spill onto soil, leach into groundwater, and are released into the air, they can have negative affects on human health as they often contain heavy metals and other dangerous materials.

14. Pathogens There are a number of ways that pathogens like bacteria, viruses, and fungi can be transmitted to humans. • Releasing untreated human sewage onto crop soil can transfer pathogens into drinking water and onto vegetables or grains. • The pathogen that causes cholera can be found in contaminated food and drinking water; cholera is a dangerous intestinal illness that plagues much of the developing world. • Some pathogens are also transmitted through the air; these airborne pathogens are either bacteria or viruses, such as Hantavirus. • Animal to human contact can also transmit pathogens; mosquitoes carry pathogens that cause malaria in people. • A recent pathogenic virus that has caused the H1N1 flu to spread around the world was caused by human to animal contact.

15. Heavy Metals • Animals and plants need small amounts of some heavy metals to be healthy; however, industry has released poisonous amounts of heavy metals into soils and water, and particles of heavy metals can also become air pollutants in the form of particulate matter • as discussed in Water Pollution, industries like metal smelting and electroplating, as well as burning coal, release heavy metals into the environment. • Researchers have found that carrots are very good at absorbing heavy metals, such as lead and arsenic, from contaminated soils. •  “What Lies Beneath” news article analysis