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Air Pollution



• Air pollution not distributed uniformly, mostlyconcentrated around urban areas

• Sources of pollution: In and around urban areassuch as automobiles, industrial emissions

• Form of air pollution: Urban smog

• Affected by meteorology and topography

Urban Air Pollution



Figure 18.5

Urban Smog



Temperature Inversions• Depending on the geographical location,

temperature, wind and weather factors, pollution isdispersed differently. However, this sometimesdoes not happen and the pollution can build up to

dangerous levels.• A temperature inversion occurs when air close to

the Earth is cooler than the air above it. Underthese conditions the pollution cannot rise and bedispersed.

– Cities surrounded by mountains also experience trappingof pollutants

– Winter inversions are likely to cause particulate andcarbon pollution

– Summer inversions are more likely to create smog



1930: Meuse River Valley, Belgium

• An inversion led to a high concentration of pollutants during a period of cold, dampweather

• Main sources: zinc smelter, sulfuric acid factory,glass manufacturers

• 60 deaths recorded

1948: Donora, Pennsylvania

• Similar inversion to Meuse River Valley

• Main sources: iron and steel factories, zincsmelting, and an acid plant

• 20 deaths observed

1952: London

• Killer fog (right)

• Primary source: domestic coal burning

• 4,500 excess deaths recorded during week-long period in December

•The Great London Smog

(1952)

Major Episodes of Severe Air Pollution due toInversions

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11247570&dopt=Abstract

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Consequences of Air Pollution

• CO2 is a good transmitter of sunlight, butit also partially restricts infrared radiation

going back from the earth into space,which produces the so-called greenhouseeffect that prevents a drastic cooling of the Earth during the night



Consequences of Air Pollution

• Increasing the amount of CO2 in theatmosphere reinforces this effect and isexpected to result in a warming of the

Earth's surface

• CO2 in atmosphere GLOBALWARMING



The Greenhouse Effect



•Diagram: Greenhouse Effect



Greenhouse Effect• The Greenhouse Effect, also referred to as global

warming, is generally believed to come from thebuild up of carbon dioxide gas in the atmosphere.

• Plants convert carbon dioxide back to oxygen, butthe release of carbon dioxide from human activitiesis higher than the world’s plants can process.

• This situation is made even worse since many of the Earth’s forests are being removed, and plant life

is being damaged by acid rain.

• The buildup of carbon dioxide acts like a blanketand traps heat close to the surface of the earth.



Acid Rain• When emissions of sulfur dioxide and

nitric oxide from stationary sources aretransported long distances by winds, they

form secondary pollutants such asnitrogen dioxide, nitric acid vapor, anddroplets containing solutions of sulfuricacid, sulfate, and nitrate salts

• These chemicals descend to the earth'ssurface in wet form as rain or snow andin dry form as a gases fog, dew, or solidparticles, it is known as acid rain or aciddeposition



•The Process of Acid Rain



Acid Rain: Its effect on a tree



Consequences continued

• Sulfur dioxide, nitrogen oxides, ozoneand peroxyacl nitrates (PANs), causedirect damage to leaves of crop plants

and trees when they enter leaf pores(stomates)

• Chronic exposure of leaves and needlesto air pollutants can also break down thewaxy coating that helps preventexcessive water loss and damage fromdiseases, pests, drought and frost



Consequences continued

• "In the midwestern United States crop

losses of wheat, corn, soybeans, andpeanuts from damage by ozone and aciddeposition amount to about $5 billion ayear". (Miller 498)



Effects of air pollution



Effects on Human Beings• Increases in air pollution have

been linked to decreases inlung function and increases inheart attacks.

• High levels of air pollutionaccording to the EPA AirQuality Index directly affectpeople with asthma and othertypes of lung or heart disease.

• Long-term exposure to airpollution can cause cancer andlong-term damage to theimmune, neurological,reproductive, and respiratorysystems. In extreme cases, itcan even cause death.



Around 30-40% of cases of

asthma and 20-30% of allrespiratory diseases may be

linked to air pollution



- increased acute respiratory diseases

- lowered lung function in children

- increased sickness rates;- increases in mortality



why specially in children

- Children spend more time- outdoorsespecially in the summertime when

ozone levels are the highest

- engaged in vigorous activity- Have a higher breathing rate

- Not likely to receive / understand thebiological warnings

- Breathe through mouth also - Have narrower airways - Impairment of the lung's ability to

defend itself



• Premature death

• Lung cancer

• Development of chronic lung disease• Heart attacks

• Respiratory symptoms and medication use inpeople with chronic lung disease and asthma

• Decreased lung function

• Pre-term birth

• Low birth weight

What Adverse Health Effects

Have Been Linked to PM?



Several theories have been advanced as to the mechanism of action. It is likely that more than one mechanism is involved incausing PM-related health effects. Theories include the following:

4. PM causes inflammation of lung tissue, resulting in

the release of chemicalsthat impact heart function;

5. PM causes changes inblood chemistry thatresults in clots that can

cause heart attacks.

1. PM leads to lung irritation which leads to increase

permeability in lung tissue;2. PM increases susceptibility to

viral and bacterial pathogens leading to pneumonia invulnerable persons who are

unable to clear these infections;3. PM aggravates the severity

of chronic lung diseases causing rapid loss of airwayfunction;

How Does PM Cause Health Effects?



Increasing Evidence of

Cardiovascular Effects•Until the mid 1990s, mostresearch focused on theassociation of PM exposure

with respiratory disease.Since then, there has beengrowing evidence of cardiovascular health

effects from PM.



•Reduce emissions (conservation and improvedefficiency); e.g., refineries

• Collect, capture, and retain pollutants beforeentering the atmosphere

• Regulating automobile exhaust using catalyticconverter

• Varied pollutant-control strategies and new and

improved technologies

Control of Air Pollution



•Maximum emission levels Many nations have their own standards;

however, no international standards in place

•

In the U.S., the Clean Air Act in 1970 andsubsequent amendments in 1977 and 1990

Goal: Reducing carcinogens up to 90%

• Monitoring air pollution: Air Quality Index

(AQI)

Air Quality Standards



Air Quality Index (AQI)

• The AQI is a national index for reporting daily airquality and it can be found in newspapers,television reports, radio reports, and on theinternet.

• The AQI tells you how clean or polluted your airis, and what associated health effects might be aconcern for you.

• To make it easier to understand, the AQI isdivided into six numerical ranges.

– The higher the AQI value, the

greater the level of air pollution

and the greater the health concerns.



Control of air pollution



Ideas to Reduce Air Pollution

• Scientists, legislative bodies, educators, andagencies must come together to make theworld a cleaner place by setting controls on

pollution emissions for industries andautomobiles.

• Automobiles: a problem of numbers!

– Besides carpooling, using public transportation,and other friendlier methods…we need to havecleaner cars

• These cleaner cars would need to use nonleaded fuel,and improvements will need to made on valves,different fuel to air ratios, exhaust recycling, thermalexhaust reactors, and catalytic converters.



Process of Pollutant Removal

• Different pollutants have different life spansbased on the chemical reactivity of theirmolecules. For example:

– Methane remains in the atmosphere for years

– Carbon dioxide stays for centuries

– Sulfates stay in the atmosphere for only a fewdays to weeks before falling or raining out

• The atmosphere contains cleansing agentsthat break up pollution molecules.

– Among the most important of these agents isthe hydroxyl radical (OH)

• It prevents toxic buildups by oxidizing pollution andmany naturally occurring chemicals in the air



Removing Sulfur Dioxide – “scrubbers”



Society

Industries – Legislation

– guidelines for siting of industries

– emission standards for industries – development of pollution prevention

technologies

Vehicular pollution

– stringent emission norms

– cleaner fuel quality



What can we do to protectour kids?



Keep an eye on child’s health

Look for warning signsshare observations with pediatrician.

Asthmatic child

recognize triggers and avoid themon bad air days they react more

strongly to triggers than usual



Make indoor environment "lung healthy"

Smoke-freeregular cleaningleaks or moisture problems



Keep track of air pollution levels

limit the outdoor time in vigorous playduring unhealthy airtime

Plan the most strenuous activities forthe early morning hours

Keep outdoor activities away from busyroadways and other sources of pollution.

Make child’s guides aware of the health risksof air pollution, and frame policies



Proper disposal of waste

- dry leaves, old tyres,plastics & garbage

Shift to cleaner fuels- vehicle, cooking

Save enegry - decrease fuel consumption

Diwali

Speak out in support of clean air

C f C lli Ai P ll i



•Currently, billions per year in an attempt tocontrol air pollutants

• Higher cost of many industrial products andservices, such as automobiles and fuel

• Debates over costs vs. benefits, new pollutantsin controlling old ones

• Hard to quantify the variables, air quality

critical in developing a minimum acceptablepollution level

Cost of Controlling Air Pollution

Future of Air Pollution in Urban



•Air pollution level improved in many cities indeveloped countries

• Air pollution level worsened in many cities inpopulated and poor

countries, vulnerableeven in the foreseeablefuture

•

Reduction of pollutantemissions, including SO2and VOCs, through fuelefficiency, improved fuel

and technology

Future of Air Pollution in Urban Areas



•Overview of Air Pollution



Thanks

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