| Username |
Post |
| missgrg |
Posted
on 23-Mar-03 10:42 AM
The layer of air which supports life extends about 8 km above the Earth's surface and is known as troposphere. The composition of air remains remarkably constant except there may be small localised variations. AP has existed since humans first used fire. The problem becomes significant since the industrial revolution in the 19th century. Almost all air pollutants is the result of burning fossil fuels, either in the home, by industry or in internal combustion engine.
Pollutants are smog(ozone), carbon monoxide and particulates, gasoline produced volatile, organic compounds, combustion products, nitrogen dioxide, sulfur dioxide and lead. Sources of pollutants are traffic vehicle, industries, aircraft, power generation (heat) etc.
Criteria air pollutants- will be harmful to health and the environment, and will be regulated by first developing health-based criteria as the base for setting levels. Primary standard protects health, secondary standard prevent environmental and property damage.
AP is very serious in large metropolitan cities like New York, United Kingdom, Australia, Hong Kong, Canada. That's not only affects the quality of air we breath, but also our health, the image of the city, worldwide as well as our future generations.
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| ugly duckling |
Posted
on 23-Mar-03 04:04 PM
>AP is very serious in large metropolitan cities like New York, United Kingdom, Australia, Hong Kong, Canada.
United Kingdom, Australia, and Canada are not metropolitan cities :)
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| Arnico |
Posted
on 23-Mar-03 04:20 PM
Missgrg, glad to see someone else who is interested in atmospheric science.
I hope you don't mind if I give some comments/additions. Hope you find these helpful.
The height of the troposphere tends to vary a bit, between about 10 km and 14-15 km.
It is interesting that you consider it the layer that supports life. The atmospheric composition much higher up would support life as well, but for most organisms would need to be compressed first (that's what happens when you fly at 12-13 km altitude). In fact even at 8 km, lots of organisms have trouble breathing (including most humans).
As for atmospheric composition remaining constant in the troposphere: generally so, except for (1) water vapor which varies widely, and (2) short-lived pollutants and other reactive gases near their sources.
Whether air pollution has existed since people first started using fire, or since the first fire started (long before people existed), or only since the first human became sick because of it... that's a matter of definition... so I won't comment on that.
However, I think the statement that most air pollution is a result of fossil fuel combustion is a bit too general. In urban areas a lot of it is. A lot of greenhouse gases are. But, there is also a lot of pollution due to biomass burning (especially in rural areas in Nepal), as well as anywhere with forest first fires etc.... and often windblown dust can also be considered "pollution"...
Your list of pollutants is quite complete... except that there are also a lot of VOCs that are not produced from gasoline combustion...
As for the cities with serious air pollution problems... well... New York and Hong Kong have problems, but far less serious than Los Angeles, Mexico City, Beijing, Delhi, Sao Paolo, Santiago de Chile, Tehran...
As for the UK, Australia, and Canada... last I knew, they were still countries, and not just cities...
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| missgrg |
Posted
on 23-Mar-03 10:24 PM
UD! sorry,was mistaken metropolitan- New York, HK and other industrilized countries like Australia, Canada etc..
Arnico! actually i was posting this material to let everybody know what is AP and what are the causes and ofcourse everybody can participate it. You can give more additiion and comment we all will be happy to read.
I am agree with your first two para.
Where as - "But, there is also a lot of pollution due to biomass burning (especially in rural areas in Nepal), as well as anywhere with forest first fires etc.... and often windblown dust can also be considered "pollution"... - i was talking about develloped countries.
Anyway developing countries are suffering from smoke and dust pollution too.
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| MissGrg |
Posted
on 23-Mar-03 10:38 PM
Pllutants of current interest are ozone, particulate, nitrogen dioxside.
although individual air pollutants can exert their own specific individual toxic effects on the respiratory and cardivascular systems. Ozone, oxides of nitrogen and suspended particulates all share common properly of being poten oxidants.
AP can increase plasma viscosity, heart rate and concentrations of C- reactive protein all of which can contribute to an risk of cardiovascular events.
an inflammatory response induced in the lung on exposure to ozone together with increasing neuropeptide release from sensory neurons, contributes to the acute broncho constictor response and hyper- responsiveness seen in asthma.
Ozone increase the sythesis of the allergic antibody which increase senstization to common allergens.
Nitrogen dioxide might contribute toexacerbation of respiratory disease there by increasing the risk of lung infection.
In relation to particulate pollution, increased concentration of fibrinogen and platelets have been detected with increasing risk to cardiac arrythmia.
So see how our health effecting from AP
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