Acutedue to exposure to high concentration of pollutants lead to many disasters .

Chronic due to long term exposure to low levels of pollutants lead to many respiratory aliments .

Health effects include both acute and chronic problems e.g., asthma, eye, possibly emphysema, nose and throat irritation, and even death). The elderly and children are the most susceptible. Environmental effects as smog, green house effect and global warming.

Hazards of air pollution

Smog is an unhealthy mixture

of air pollutantsCase study (1)

Photochemical oxidants• They arise from a series of complex

atmospheric reactions between hydrocarbons and nitrogen oxides.

• Ozone is one of the most important constituents of this group.

• The mixture of ozone, peroxyacetyl nitrate (PAN), aldehydes and ketones form a haze which is termed as photochemical smog ( it is defined as a reddish brown haze in the atmosphere).

Photochemical smog

• Photochemical smog is a brown-air smog. • It is formed through light-driven chemical reactions of primary pollutants and normal atmospheric compounds that produce a mix containing over 100 chemicals. •This affects many cities.

Killer Smog

On December 5th, 1952, a dense smog enveloped the city of London. From various news accounts, it shutdown the city for four days, and was credited with the death of more than 4,000 people during the fog, and 8,000 afterwards.

Green house effects Case study (2)

Carbon dioxide • Carbon dioxide and water vapors are

responsible for maintaining earth's temperature.

• About 50% of the solar energy is absorbed

by earth and rest by the atmosphere after reflection.

• Carbon dioxide, water vapors and other gases in atmosphere absorbed large part of energy and emit it towards the ground where it warms the surface of earth and referred as natural green house effect.

• More is the production of carbon dioxide, more is its concentration in the atmosphere, more is the earth temperature.

• Carbon dioxide is the main green house gas contributing about 49% toward green house effect. Other gases are methane (18%), N2O (6%), chlorofluorocarbons (14%) and others (13%).

Global warming Case study(3)

Global warming• It is the observed rise in the average temperature of Earth's

climate system.

• Since 1971, 90% of the increased energy has been stored in the oceans, mostly in the 0 to 700m region.

• Despite the oceans' dominant role in energy storage, the term "global warming" is also used to refer to increases in average temperature of the air and sea at Earth's surface.

• Since the early 20th century, the global air and sea surface temperature has increased about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980.

Causes

• The most of global warming was being caused by increasing concentrations of greenhouse gases produced by human activities .

• The largest driver of global warming is carbon dioxide (CO2) emissions from fossil fuel combustion, cement production, and land use changes such as deforestation.

• Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes.

The effects of an increase in global temperature

• A rise in sea levels and a change in the amount and pattern of precipitation, as well as a probable expansion of subtropical deserts.

• Warming is expected to be strongest in the Arctic, with the continuing retreat of glaciers, permafrost and sea ice.

• Other likely effects of the warming include more frequent extreme weather events including heat waves, droughts and heavy rainfall; ocean acidification; and species extinctions due to shifting temperature regimes.

• Effects significant to humans include the threat to food security from decreasing crop yields and the loss of habitat from inundation.

Global warming

Reductions in snow and ice Retreat of glaciers, permafrost and sea ice

Global warming Species extinctions

Acute exposure to air pollutants

Lead to many DISASTERS ٍ

Bhopal gas tragedy due to methyle-isocyanate .

Case study (4)

THE BHOPAL DISASTER

• Around 1 a.m. on Monday, the 3rd of December, 1984, In the city of Bhopal, Central India, a poisonous vapour burst from the tall stacks of the Union Carbide pesticide plant. • This vapour was a highly toxic cloud of methyl isocyanate. •2,000 died immediately•300,000 were injured •7,000 animals were injured, of which about one thousand were killed.

THE POSSIBLE CAUSES

• A tank containing methyl isocyanate (MIC) leaked.• MIC is an extremely reactive chemical and is used in

production of the insecticide carbaryl. • The scientific reason for the accident was that water entered

the tank where about 40 cubic meters of MIC was stored. • When water and MIC mixed, an exothermic chemical reaction

started, producing a lot of heat. • As a result, the safety valve of the tank burst because of the

increase in pressure. • It is presumed that between 20 and 30 tonnes of MIC were

released during the hour that the leak took place.• The gas leaked from a 30 m high chimney and this height

was not enough to reduce the effects of the discharge.

Eye lesion due to cyanide poisoning

Chronic exposure to air pollutants

Lead to many DESEASES ٍ

Silo Filler’s Disease case study (5)

Silo Filler’s Disease

• A disease caused by the inhalation of nitrogen oxides– Toxic levels of NO, NO2, N204 are all produced in

silos– These gases are dense and settle in the chute and

base of the silo– NO2 is brown and has an odor

– N204 is colorless and odorless– When inhaled, they make nitric acid

Silo Filler’s Disease• Clinical signs– Mild exposure: cough, chest tightness– Large exposure: vascular collapse, shock, death

• P/M lesions- Lung fibrosis

Nitrogen oxides