Tag: smoke, dust and other air pollutants, acid rain

Nowadays, the mixture of particulates with gaseous oxides of sulphur present in the atmosphere is called classical smog. The principal source of classical smog is the combustion of industrial and household fuels (coal and petroleum). Because of the presence of $S{ O } _{ 2 }$ and carbon (soot) particles, classical smog has a reducing character. It occurs in winter months, particularly in early morning hours. It causes severe lung and throat irritation.

The reaction of sunlight with hydrocarbons and ${ NO } _{ 2 }$ results in a variety of chemical products. One of these is ozone, made up of 3 atoms of oxygen, which is an irritating noxious gas. Other undesirable chemicals such as aldehydes also result from this photochemical reaction. This type of smog is oxidizing in character because of the presence of ozone, nitrogen dioxide, and some photochemical oxidants.

The reaction of sunlight with hydrocarbons and ${ NO } _{ 2 }$ results in a variety of chemical products. One of these is ozone, made up of 3 atoms of oxygen,which is an irritating noxious gas. Other undesirable chemicals such as aldehydes also result from this photochemical reaction. This type of smog is oxidizing in character because of the presence of ozone,nitrogen dioxide and some photochemical oxidants.

Acute harm due $N{ O } _{ 2 }$ exposure is only likely to arise in occupational settings. Direct exposure to the skin can cause irritations and burns. Only very high concentrations of the gaseous form cause immediate distress: 10–20 ppm can cause mild irritation of the nose and throat, 25–50 ppm can cause edema leading to bronchitis or pneumonia, and levels above 100 ppm can cause death due to asphyxiation from fluid in the lungs. There are often no symptoms at the time of exposure other than transient cough, fatigue or nausea, but over hours inflammation in the lungs causes edema.

1. When exposed to oxygen, ntric oxide is converted into nitrogen dioxide  $2NO+{ O } _{ 2 }→2N{ O } _{ 2 }$
2.  Nitrogen dioxide , a brown toxic gas and a major air pollutant.
   

NO binds rapidly to haem iron in Hb and once bound, the NO activity is largely irretrievable, the binding is purportedly so tight as to be unaffected by ${ O } _{ 2 }$ or CO. So, NO has the greatest affinity toward haemoglobin. 

Of the $N{ O } _{ x }$  absorbed by acid, typically less than 10% enters the large flow of acid circulating around the acid towers. Instead, it concentrates on the much smaller quantity of acid mist formed at the inlet to the absorber towers. There are several reactions involved, but the net result can be summarised as: 

The gaseous pollutants of the atmosphere are harmful gaseous oxides and oxidants. The harmful gaseous oxides include the oxides of sulphur, nitrogen, and carbon, besides hydrocarbons.

Sources of lead emissions vary from one area to another. At the national level, major sources of lead in the air are ore and metals processing and piston-engine aircraft operating on leaded aviation fuel. Other sources are waste incinerators, utilities, and lead-acid battery manufacturers. The highest air concentrations of lead are usually found near lead smelters.

Agriculture is by far the biggest source of ammonia emissions. Livestock farming and animal waste account for the biggest percentage of total ammonia emissions which are due to the decomposition of urea from large animal wastes and uric acid from poultry wastes.

The most common pollutant of nitrogen gas is nitrogen dioxide, is produced when fossil fuels are burnt in high temperature like in automobile engines.