CE 371 ENVIRONMENT AND POLLUTION QUESTIONS & ANSWERS FOR MODULE II 1. Define air pollution. Discuss the causes for indoor and ambient air pollution Air pollution Air is one of the five essentials for the human being. A man breathes 22000 times in a day and inhales approximately 15 kg of air per day. Even though the air is abundantly available over the surface of the earth, it contains lot of impurities. In general air pollution means the presence of a foreign matter in air. Various authors define air pollution which are as follows; • DEAN E. PAINTER define air pollution as the presence in the outdoor atmosphere of one or more contaminants in a sufficient quantity and duration to cause them to be injurious to human health and welfare and animal and plant life and to interfere with the enjoyment of the life and property. • WHO defines air pollution as the excessive concentration of foreign matter in the air which adversely affects the well being of the individual or cause damage to property. • A typical legal definition for air pollution is the presence in the outdoor atmosphere of substance or contaminants put there by man, in quantities or concentrations and of a duration as to cause any; discomfort to a substantial number of inhabitants of a district of which are injurious to public health or to human, plant or animal life or property or which the reasonable comfortable enjoyment of life and property throughoutKTUNOTES.IN the state or throughout such territories or areas of the state as shall be affected thereby. • Air pollution is the presence of pollutants in air in sufficient quantity and duration which adversely affect the health and enjoyment of property of the human being, animal and plants. Causes for indoor and ambient air pollution Indoor: Indoor air pollution is a major health concern, especially for people with asthma and allergies. Here are some of the most common causes of indoor air pollution. (i) Radon It is an invisible, radioactive, colourless, odourless gas. Radon may be found in certain rock formations underneath your home and in some building materials. Unlike the gas radon itself, radon daughters are solid and stick to surfaces, such as dust particles in the air. If such contaminated dust is inhaled, these particles can cause lung cancer. Epidemiological studies have shown a clear link between breathing high concentration of radon and incidence of lung cancer. It Compiled by Dr. Hema Nalini A.V., Professor of Civil Engineering, NSS College of Engg. Downloaded from Ktunotes.in 2 is a contaminant that affects indoor air quality worldwide. According to the United States environmental protection agency, radon is the second most frequent cause of lung cancer, after cigarette smoking. (ii) Smoke Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. Not only second-hand cigarette smoke but also smoke from fireplaces stoves and cooking fires. It is commonly an unwanted by-product of fires, but may also be used for pest control, communication, defensive and offensive capabilities in the military, cooking or smoking. Smoke inhalation is the primary cause of death in victims of indoor fires. The smoke kills by a combination of thermal damage, poisoning and pulmonary irritation caused by carbon monoxide, hydrogen cyanide and other combustion products. (iii) Volatile organic compounds (VOCs) These are organic chemicals that have a high vapour pressure at ordinary room temperature. And are Toxic gases that are emitted from certain solids or liquids. VOCs can be found in a long list of common household products including paints, varnishes, paint removers, cleaning products, building materials, glues, adhesives and office equipment such as printers and copiers. VOCs play an important role in communication between plants, and messages from plants to animals. Some VOCs are dangerous to human health or cause harm to the environment. Anthropogenic VOCs are regulated by law, especially indoors, where concentrations are the highest. Harmful VOCs typically are not acutely toxic, but have compounding long-term health effects. Because the concentrations are usually low and the symptoms slow to develop, research into VOCs and their effects is difficult. KTUNOTES.IN (iv) Mold Mold is a fungus that grows in the form of multicellular filaments called hyphae. In contrast, fungi that can adopt a single-celled growth habit are called yeasts. It is an allergen that can also be harmful to anyone who is exposed to it for lengthy periods of time. Mold typically grows in damp, warm and dark conditions. Some diseases of animals and humans can be caused by certain molds: disease may result from allergic sensitivity to mold spores, from growth of pathogenic molds within the body, or from the effects of ingested or inhaled toxic compounds (mycotoxins) produced by molds. Some studies claim that exposure to high levels of mycotoxins can lead to neurological problems and in some cases, death. Prolonged exposure, e.g. daily home exposure, may be particularly harmful. (v) Carbon monoxide Carbon monoxide (CO) is a colourless, odourless, and tasteless gas that is slightly less dense than air results from the burning of fossil fuels. Carbon monoxide can be emitted from cigarettes, defective furnaces and other heating devices as well as from automobiles. It is toxic to Compiled by Dr. Hema Nalini A.V., Professor of Civil Engineering, NSS College of Engg. Downloaded from Ktunotes.in 3 haemoglobin animals (both invertebrate and vertebrate, including humans) when encountered in concentrations above about 35 ppm, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. (vi) Asbestos Asbestos is a set of six naturally occurring silicate minerals found in building materials used before 1975. It was used in such applications as electrical insulation for hotplate wiring and in building insulation. When asbestos is used for its resistance to fire or heat, the fibres are often mixed with cement or woven into fabric or mats. It is harmful when inhaled into the lungs. Prolonged inhalation of asbestos fibres can cause serious and fatal illnesses including lung cancer, mesothelioma, and asbestosis (a type of pneumoconiosis) Asbestos continues to be a concern in many older buildings. (vii) Broken fluorescent bulbs Whenever compact fluorescent bulbs break, they release small amounts of mercury in the air which drops on surfaces and the carpets or suspend in the air. As a result, it causes indoor air pollution since the particles contaminate the air. Mercury is a neurotoxin which can seriously impact human health. (viii) Pesticides Pesticides very purpose is to kill, so clearly, you do not want to be continuously inhaling them at home. Pesticides release a variety of chemicals into the air. Pesticide containers in the home are the primary source of this pollutant, but pesticide can also be unwittingly tracked in from the yard by those who use them outside. Pesticides can irritate the eyes, nose, and throat, and they are detrimental to the centralKTUNOTES.IN nervous system and the kidneys. They are also associated with an increased risk of cancer. Outdoor: Sources of outdoor or ambient air pollution are varied and include both natural and man-made ones. Natural outdoor air pollution includes oxides of sulphur and nitrogen from volcanoes, oceans, biological decay, lightning strikes and forest fires, VOCs and pollen from plants, grasses and trees, and particulate matter from dust storms. Natural pollution is all around us all of the time. However, sometimes concentrations can increase dramatically, for example after a volcanic eruption, or at the beginning of the growing season. The common sources of outdoor air pollution are emissions caused by combustion processes from motor vehicles, solid fuel burning and industry. Other pollution sources include smoke from bushfires, windblown dust, and biogenic emissions from vegetation (pollen and mould spores). The main causes of ambient air pollution are; Combustion of fossil fuels: (i) Domestic heating Compiled by Dr. Hema Nalini A.V., Professor of Civil Engineering, NSS College of Engg. Downloaded from Ktunotes.in 4 In terms of heating systems, portable kerosene cookers and heaters emit significant particulate matter, including black carbon emissions, directly into the household environment or outdoors, if the system is closed. Portable gas heaters emit comparatively less particulate matter, but can still release excessive quantities of NOx into the indoor environment as well as creating risks of carbon monoxide poisoning. Central heating systems, whereby fuel is burned in a contained boiler, heating water or another circulation liquid, usually provide a clean indoors environment. However, Systems that burn diesel or fuel oil tend to release significant particulate matter outdoors - contributing to ambient air pollution as well as to climate change – through both CO2 and black carbon emissions. Central heating systems that operate on natural gas or liquefied petroleum gas fuels generally emit far less particulate matter, including far less black carbon, as well as lower CO2 emissions. (ii) Power generation. Coal power plants release large amounts of sulphur dioxide and nitrogen oxides. Nitrogen oxides are greenhouse gases, but these pollutants also react with organic compounds to form smog (ground level ozone). Harmful to our health, smog increases risk of asthma, lung damage and premature death. It also damages plants, making them vulnerable to disease and extreme weather. Nitrogen oxides and sulphur dioxide also contribute to acid rain. When these pollutants mix with water, oxygen, and other chemicals in the air, they form nitric and sulphuric acid. The resulting acid rain can spread over a wide area, killing fish and plants. In forests, acid rain damages tree leaves and strips nutrients from soils.