Essay on Important Methods of Detection and Measurement of Air Pollution !
Air pollution is usually measured by sampling of air by thermal and by electrostatic precipitation, Sonkin impactor and electrostatic dust collectors.
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Table 251. Common air pollutants, their sources and pathological effects on man (after Southwick, 1976):
| Pollutants | Where they come from (source) | Pathological effect on man |
| 1. Aldehydes | Thermal decomposition of fats, oil, or glycerol. | Irritate nasal and respiratory tracts. |
| 2. Ammonias | Chemical processes—dye- making; explosives; lacquer; fertilizer. | Inflame upper respiratory passages. |
| 3. Arsines | Processes involving metals or acids containing arsenic soldering. | Break down red cells in blood, damage kidneys; cause jaundice. |
| 4. Carbon monoxides | Gasoline motor exhausts; burning of coal. | Reduce oxygen-carrying capacity of blood. |
| 5. Chlorines | Bleaching cotton and flour; many other chemical processes. | Attack entire respiratory tract and mucous membranes of eyes; cause pulmonary edema: |
| 6. Hydrogen cyanides | Fumigation; blast furnaces: chemical manufacturing; metal plating. | Interfere with nerve cells; produce dry throat, indistinct vision, and headache. |
| 7. Hydrogen fluorides | Petroleum refining; glass etching; aluminium and fertilizer production. | Irritate and corrode all body passages. |
| 8. Hydrogen sulphides | Refineries and chemical industries; bituminous fuels. | Smell like rotten eggs; cause nausea; irritate eyes and throat. |
| 9. Nitrogen oxides | Motor vehicle exhausts; soft coal. | Inhibit cilia action so that soot and dust penetrate far into the lungs. |
| 10. Phosgenes (carbonyl chloride) | Chemical and dye manufacturing. | Induce coughing, irritation, and sometimes fatal pulmonary edema. |
| 11. Sulphur dioxides | Coal and oil combustion. | Cause chest constriction, headache, vomiting, and death from respitratory ailments. |
| 12. Suspended particles (ash, soot, smoke) | Incinerators; almost any manufacturing. | Cause emphysema, eye irritations and possibly cancer. |
The particulate pollution is measured by the instrument called deposit gauge or by Owen’s dust counter. The thickness of the smoke is measured by Liegean sphere and by Ringelmann chart. The rough estimation of SO2 in air can be made by chemical analysis of the dust collected in a deposit gauge or by a bubbler method. Fluorides are estimated by colour reactions.
Table 25.2. Levels of sulphur dioxide (SO2) and suspended particulate matter in air during 1970 in some Indian cities (from Seth, 1976):
| City | Mean Value of SO2 microgram/cubic meter | Suspended particulate matter microgram/cubic meter | |
| 1. | Bombay | 47.1 | 240.8 |
| 2. | New Delhi | 41.4 | 601.1 |
| 3. | Calcutta | 32.9 | 340.7 |
| 4. | Kanpur | 15.9 | 543.5 |
| 5. | Ahmedabad | 10.7 | 306.6 |
| 6. | Madras | 8.3 | 100.9 |
| 7. | Nagpur | 7.7 | 261.6 |
| 8. | Hyderabad | 5.1 | 146.2 |
| 9 | Jaipur | 4.2 | 146.1 |