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.
Composition of
dry atmosphere, by volume
ppmv: parts per million by volume
Gas Volume
Nitrogen (N2) 780,840 ppmv (78.084%) Oxygen (O2) 209,460 ppmv (20.946%) Argon (Ar) 9,340 ppmv (0.9340%) Carbon dioxide
(CO2) 375 ppmv
Neon (Ne) 18.18 ppmv Helium (He) 5.24 ppmv Methane (CH4) 1.745 ppmv Krypton (Kr) 1.14 ppmv Hydrogen (H2) 0.55 ppmv
Not included in above dry atmosphere:
Water vapor
(highly variable) typically 1%
Mean Atmospheric Water Vapor.
Source for figures above: NASA. Carbon dioxide and methane updated (to 1998) by IPCC TAR table 6.1 [1]. The NASA total was 17 ppmv over 100%, and CO2 was increased here by 15 ppmv. To normalize, N2 should be reduced by about 25 ppmv and O2 by about 7 ppmv.
Minor components of air not listed above include:
Gas Volume nitrous
oxide 0.5 ppmv xenon 0.09 ppmv
ozone 0.0 to 0.07 ppmv nitrogen
dioxide 0.02 ppmv iodine 0.01 ppmv carbon
monoxide trace
Types and Sources of Air Pollution
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 Air Pollutant
Harmful 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 PrakashJavadekar. The air quality index is composed of 8 pollutants ((PM10, PM2.5, NO2, SO2, CO, O3, NH3, 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 (SO2), Nitrogen Dioxide (NO2), and Carbon Monoxide (CO) in the air exceeds the criteria set by the World Health Organization (WHO).
National Ambient Air Quality Standards
Pollutant Primary Stds. Averaging Times Secondary Stds.
9 ppm (10 mg/m3)
8-hour1 None
Carbon Monoxide
35 ppm (40 mg/m3)
1-hour1 None
Lead 1.5 µg/m3 Quarterly Average Same as Primary Nitrogen Dioxide 0.053 ppm
(100 µg/m3)
Annual (Arithmetic Mean)
Same as Primary 50 µg/m3 Annual2 (Arith.
Mean)
Same as Primary Particulate Matter
(PM10)
150 ug/m3 24-hour1
15.0 µg/m3 Annual3 (Arith.
Mean)
Same as Primary Particulate Matter
(PM2.5)
65 ug/m3 24-hour4
Ozone 0.08 ppm 8-hour5 Same as
Primary 0.03 ppm Annual (Arith. Mean) ---
0.14 ppm 24-hour1 ---
Sulfur Oxides
--- 3-hour1 0.5 ppm (1300 ug/m3)
1 Not to be exceeded more than once per year.
2 To attain this standard, the 3-year average of the weighted annual mean PM10 concentration at each monitor within an area must not exceed 50 ug/m3.
3 To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 ug/m3.
4 To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 65 ug/m3.
5 To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.08 ppm.
AQI: is used by government agencies to communicate to the public how polluted
the air currently is or how polluted it is fore cast to become. Public health risks increase as the AQI rises.
Different countries have their own air quality indices, corresponding to different national air quality standards.
Index Value
PSI
Descriptor General Health Effects
Cautionary Statements
Up to 50 Good None for the
general population. None required.
50 to 100 Moderate Few or none for the general
population.
None required.
100 to
200 Unhealthful Mild aggravation of symptoms among susceptible people, with irritation
symptoms in the healthy population.
Persons with existing heart or respiratory
ailments should reduce physical exertion and outdoor activity.
General population should reduce
vigorous outdoor activity.
200 to
300 Very
Unhealthful Significant aggravation of symptoms and decreased exercise tolerance in
persons with heart or lung disease;
widespread
symptoms in the healthy population.
Elderly and persons with existing heart or lung disease should stay
indoors and reduce physical activity.
General population should avoid
vigorous outdoor activity.
Over 300 Hazardous Early onset of
certain diseases in addition to
significant
aggravation of symptoms and
Elderly and persons with existing diseases should stay
indoors and avoid physical exertion.
SOURCES OF TROPOSPHERIC OZONE
?
?
?
Fires Biosphere Human activity Lightning
Ocean physicschemistry
biology
Nitrogen oxides (NOx) CO, Hydrocarbons
h Ozone (O3) h, H2O Hydroxyl (OH)
The Pacman of the
atmosphere!
Complex non-linear chemistry Tropopause (8-18 km)
Stratospheric ozone
STRATOSPHERE
TROPOSPHERE O2 + h
CLIMATE FORCING BY AIR POLLUTANTS
GLOBAL RADIATIVE FORCING OF CLIMATE, 1750-present [IPCC, 2001]POLLUTANT-RELATED
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 (SO2), a heavy, colorless gas with an odor like a struck match.
This gas combines easily with water vapor, forming aerosols of sulfurous acid (H2SO3), a colorless, mildly corrosive liquid.
This liquid may then combine with oxygen in the air, forming the even more irritating and corrosive sulfuric acid (H2SO4).
Other sulfur-containing compounds
Hydrogen sulfide (H
2S) 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
2released 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 SO2 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. (SO2 is a major precursor to acidic deposition.)
Sulfur oxides may also damage stone and masonry, paint, various fibers, paper, leather, and electrical components.
Increased SO2 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
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 O3 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.
formation of acid rain, which raises pH (a measure of acidity) in rivers and streams and destroys plants and trees.
Effects of air pollution on the environment Air pollution causes the
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.
Air pollution can affect wildlife indirectly by changing plant communities.
Effects of air pollution on the
environment
Atmospheric ozone can stunt growth in various plant species and these changes affect the quality of habitat and food sources of many animals.
How Does Air Pollution Affect Animals?
Pets Studies show that household pets suffer an increased risk of tumors when exposed to polluted air over an extended period of time.
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.
Rebecca Watts Hull Mothers & Others for Clean Air 404.313.1779 rebecca@mocleanair.org www.mothersandothersforcleanair.org Birds Birds are affected directly by coal power production exhaust, which can damage birds’ respiratory systems.
They also are affected by air pollution indirectly. Increase in wetlands
pH causes fish kills, resulting in a decline in the osprey population as sources of food become scarce.
Fish Acid rain falling in rivers and streams causes pH levels to rise, killing fish that are sensitive to pH fluctuations.
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 aquatic Life
Amphibians Air pollution has been linked to changes in both physiology and behavior in toads and other amphibians.
Ozone impairs immune systems in human beings and studies show it affects toads in a similar way.
Insects 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.
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.
Effects on amphibians
and insects
Acknowledg ements
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.
