Air Pollution Definition Air pollution may be defined

Air Pollution

Definition Air pollution may be defined as the presence in the air (outdoor atmosphere) of one or more contaminants or combinations thereof in such quantities and of such durations as may be or tend to be injurious to human, animal or plant life, or property, or which unreasonably interferes with the comfortable enjoyment of life or property or conduct of business.

Air Pollutant It is a substance or effect dwelling temporarily or permanently in the air , which adversely alters the environment by interfering with the health, the comfort, or the food chain, or by interfering with the property values of people. A pollutant can be solid (large or sub-molecular), liquid or gas. It may originate from a natural or anthropogenic source (or both).

It is estimated that anthropogenic sources have changed the composition of global air by less than 0. 01%. However, it is widely accepted that even a small change can have a significant adverse effect on the climate, ecosystem and species on the planet. Examples of these are acid rain, ozone in the lower atmosphere, and photochemical smog.

Types and Sources of Air Pollution Chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful Two categories Primary Air Pollutant Harmful substance that is emitted directly into the atmosphere Secondary Harmful Air Pollutant substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants

Major Air Pollutants

Major Classes of Air Pollutants Particulate Material Nitrogen Oxides Sulfur Oxides Carbon Oxides Hydrocarbons Ozone

Particulate Material Thousands of different solid or liquid particles suspended in air Includes: soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets Dangerous for 2 reasons May contain materials with toxic or carcinogenic effects Extremely small particles can become lodged in lungs

Nitrogen and Sulfur Oxides Nitrogen Oxides Gases produced by the chemical interactions between atmospheric nitrogen and oxygen at high temperature Problems Greenhouse gases Cause difficulty breathing Sulfur Oxides Gases produced by the chemical interactions between sulfur and oxygen Causes acid precipitation

Carbon Oxides and Hydrocarbons Carbon Oxides Gases carbon monoxide (CO) and carbon dioxide (CO 2) Greenhouse gases Hydrocarbons Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH 4 - methane) Some are related to photochemical smog and greenhouse gases

Ozone Tropospheric Ozone Man- made pollutant in the lower atmosphere Secondary air pollutant Component of photochemical smog Stratospheric Ozone Essential component that screens out UV radiation in the upper atmosphere Man- made pollutants (ex: CFCs) can destroy it

Sources of Outdoor Air Pollution Two main sources Transportation Industry Intentional forest fires is also high

Air Quality Index (AQI) in India Air quality indices have been created in different countries for the measurement of air quality. These indices measure the air quality in the country and indicate whether the amount of nitrogen dioxide, carbon monoxide and sulfur dioxide in the air exceeds the criteria set by the World Health Organization or not. India uses the National Air Quality Index (AQI), Canada uses the Air Quality Health Index, Singapore uses the Pollutant Standards Index and Malaysia uses the Air Pollution Index. There are many cities including Beijing, Paris where 'pollution emergency' is declared. However, India also declared the same in November 2019. What is Air Quality Index The National Air Quality Index (AQI) in India was launched on 17 September 2014 in New Delhi under the Swachh Bharat Abhiyan by the Environment Minister Shri Prakash. Javadekar. The air quality index is composed of 8 pollutants ((PM 10, PM 2. 5, NO 2, SO 2, CO, O 3, NH 3, and Pb). https: //www. jagranjosh. com/general-knowledge/what-is-air-quality-index 1573026691 -1

The Air Quality Index measures the quality of air. It shows the amount and types of gases dissolved in the air. There are 6 categories of the air have been created in this air quality index. These categories are based on air quality. These categories are; good, satisfactory, moderate, poor, very poor and severe. As the air quality deteriorates, so does the ranking of air from good to bad then very poor to severe. Air pollution means the amount of Sulfur Dioxide (SO 2), Nitrogen Dioxide (NO 2), and Carbon Monoxide (CO) in the air exceeds the criteria set by the World Health Organization (WHO).

ØAQI: is used by government agencies to communicate to the public how polluted Øthe air currently is or how polluted it is fore cast to become. Public health risks increase as the AQI rises. ØDifferent countries have own their quality air indices, corresponding to different air national quality standards.

SOURCES OF TROPOSPHERIC OZONE STRATOSPHERE O 2 + hn Tropopause (8 -18 km) Stratospheric ozone Complex non-linear chemistry ? Lightning ? Nitrogen oxides (NOx) CO, Hydrocarbons Fires TROPOSPHERE ? Biosphere Human activity hn Ozone (O 3) Ocean hn, H 2 O physics chemistry biology Hydroxyl (OH) The Pacman of the atmosphere!

CLIMATE FORCING BY AIR POLLUTANTS GLOBAL RADIATIVEPOLLUTANT-RELATED FORCING OF CLIMATE, 1750 -present [IPCC, 2001]

Health effects of Air Pollution

Health Effects of Nitrogen Oxides Short-term exposure at concentrations greater than 3 parts per million (ppm) can measurably decrease lung function. Concentrations less than 3 ppm can irritate lungs. Concentrations as low as 0. 1 ppm cause lung irritation and measurable decreases in lung function in asthmatics. Long-term lower level exposures can destroy lung tissue, leading to emphysema. Children may also be especially sensitive to the effects of nitrogen oxides.

Other Effects Seriously injure vegetation at certain concentrations. Effects include: Bleaching or killing plant tissue. Causing leaves to fall. Reducing growth rate. Deteriorate fabrics and fade dyes. Corrode metals (due to nitrate salts formed from nitrogen oxides). Reduce visibility.

Effect of Air Pollution on Plants

Other Effects (Continued) Oxides of nitrogen, in the presence of sunlight, can also react with hydrocarbons, forming photochemical oxidants or smog. Also, NOx is a precursor to acidic precipitation, which may affect both terrestrial and aquatic ecosystems.

Sulfur Dioxide Ninety-five percent of pollution related sulfur oxide emissions are in the form of sulfur dioxide (SO 2), a heavy, colorless gas with an odor like a struck match. This gas combines easily with water vapor, forming aerosols of sulfurous acid (H 2 SO 3), a colorless, mildly corrosive liquid. This liquid may then combine with oxygen in the air, forming the even more irritating and corrosive sulfuric acid (H 2 SO 4).

Other sulfur-containing compounds Hydrogen sulfide (H 2 S) gas - rotten eggs. Mercaptans - skunk spray or decayed garbage. (Added in trace amounts to natural gas, providing a leak-detecting warning odor. ) Note: The amount of SO 2 released from coal fired power plants depends on the sulfur content of coal, normally 0. 7% to 2% by weight. High sulfur coal sometimes contains as much as 6% sulfur by weight. In India, sulfur content is quite low.

Health Effects of Sulfur Oxides Sulfur dioxide not only has a bad odor, it can irritate the respiratory system. Exposure to high concentrations for short periods of time can constrict the bronchi and increase mucous flow, making breathing difficult. Children, the elderly, those with chronic lung disease, and asthmatics are especially susceptible to these effects.

Sulfur dioxide can also: Immediately irritate the lung and throat at concentrations greater than 6 parts per million (ppm) in many people. Impair the respiratory system's defenses against foreign particles and bacteria, when exposed to concentrations less than 6 ppm for longer time periods. Apparently enhance the harmful effects of ozone. (Combinations of the two gases at concentrations occasionally found in the ambient air appear to increase airway resistance to breathing. )

Sulfur dioxide tends to have more toxic effects when acidic pollutants, liquid or solid aerosols, and particulates are also present. (In the past, thousands of excess deaths occurred in areas where SO 2 concentrations exceeded 1 ppm for a few days and other pollutants were also high. ) Effects are more pronounced among mouth breathers, e. g. , people who are exercising or who have head colds.

Sulfur oxides Effects on Plants Sulfur dioxide easily injures many plant species and varieties, both native and cultivated. Some of the most sensitive plants include various commercially valuable pines, legumes, red and black oaks, white ash, alfalfa and blackberry. The effects include: Visible injury to the most sensitive plants at exposures as low as 0. 12 ppm for 8 hours. Visible injury to many other plant types of intermediate sensitivity at exposures of 0. 30 ppm for 8 hours. Positive benefits from low levels, in a very few species growing on sulfur deficient soils.

Other Effects Increases in sulfur dioxide concentrations accelerate the corrosion of metals, probably through the formation of acids. (SO 2 is a major precursor to acidic deposition. ) Sulfur oxides may also damage stone and masonry, paint, various fibers, paper, leather, and electrical components. Increased SO 2 also contributes to impaired visibility. Particulate sulfate, much of which is derived from sulfur dioxide emissions, is a major component of the complex total suspended particulate mixture.

Health Effects of Ozone acts as a powerful respiratory irritant at the levels frequently found in most of the nation's urban areas during summer months. Ozone exposure may lead to: Shortness of breath. Chest pain when inhaling deeply. Wheezing and coughing. Long-term, repeated exposure to high levels of ozone may lead to large reductions in lung function, inflammation of the lung lining, and increased respiratory discomfort.

How air pollutants affect the respiratory system Several mechanisms have been suggested to explain the adverse effects of air pollutants. The most consistent and most widely accepted explanation is that, once in contact with the respiratory epithelium, high concentrations of oxidants and pro-oxidants in environmental pollutants such as PM of various sizes and compositions and in gases such as O 3 and nitrogen oxides cause the formation of oxygen and nitrogen free radicals, which in turn induce oxidative stress in the airways. In other words, an increase in free radicals that are not neutralized by antioxidant defenses initiates an inflammatory response with release of inflammatory cells and mediators (cytokines, chemokines, and adhesion molecules) that reach the systemic circulation, leading to subclinical inflammation, which not only has a negative effect on the respiratory system but also causes systemic effects.

Effects of air pollution on the environment formation of acid rain, which raises p. H (a measure of acidity) in rivers and streams and destroys plants and trees. v. Effects of air pollution on the environment Air pollution causes the v. Hazy smog attributed to sources as far away as Chicago as well as nearby Atlanta affects north Georgia’s mountainous terrain, resulting in an 80% visibility loss in the summer and a 40% visibility loss in winter. v Air pollution can affect wildlife indirectly by changing plant communities.

v. Atmospheric ozone can stunt growth in various plant species and these changes affect the quality of habitat and food sources of many animals. v. How Does Air Pollution Affect Animals? v. Pets Studies show that household pets suffer an increased risk of tumors when exposed to polluted air over an extended period of time. v. Particulate matter in the air has been linked to cardiac arrest in dogs and veterinarians sometimes attribute pet deaths to the effects of air pollution. v. Rebecca Watts Hull Mothers & Others for Clean Air 404. 313. 1779 rebecca@mocleanair. org www. mothersandothersforcleanair. org Birds are affected directly by coal power production exhaust, which can damage birds’ respiratory systems.

Effects on aquatic Life v. They also are affected by air pollution indirectly. Increase in wetlands p. H causes fish kills, resulting in a decline in the osprey population as sources of food become scarce. v. Fish Acid rain falling in rivers and streams causes p. H levels to rise, killing fish that are sensitive to p. H fluctuations. v. Acidic rivers and streams can cause respiratory distress in fish. Acidic water is generally clearer, causing a temperature and light increase in the water, resulting in the relocation of native fish that need a cooler and darker habitat in order to survive

Effects on amphibians and insects v. Amphibians Air pollution has been linked to changes in both physiology and behavior in toads and other amphibians. v. Ozone impairs immune systems in human beings and studies show it affects toads in a similar way. v Insects are very susceptible to air pollution. Small fluctuations in air quality force certain insects to relocate, affecting other plants and animals connected to them. v Insects that are more resilient to air pollution are those that digest organic waste less effectively, which can result in a buildup of organic waste when air pollution rises in an area.

Acknowledgements Ø Ø The slides were assembled from free downloadable web sources, PPT, books, etc. The material used in this presentation is only for discussion in the classroom. All the sources are highly acknowledged. Thanks!!!