Primary And Secondary Pollutants – Environment Notes For – W.B.C.S. Examination.

প্রাথমিক ও মাধ্যমিক দূষণকারী – পরিবেশ সংক্রান্ত নোট – WBCS পরীক্ষা।

• A primary pollutant is an air pollutant emitted directly from a source.Continue Reading Primary And Secondary Pollutants – Environment Notes For – W.B.C.S. Examination.
• A secondary pollutant is not directly emitted as such, but forms when other pollutants (primary pollutants) react in the atmosphere.
• Examples of a secondary pollutant include ozone, which is formed when,

1. hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight;
2. NO combines with oxygen in the air; and
3. acid rain, which is formed when sulfur dioxide or nitrogen oxides react with water.

Sulfurous smog

• Sulfurous smog is also called “London smog,” (first formed in London).
• Sulfurous smog results from a high concentration of SULFUR OXIDES in the air and is caused by the use of sulfur-bearing fossil fuels, particularly coal (Coal was the mains source of power in London during nineteenth century. The effects of coal burning were observed in early twentieth century).
• This type of smog is aggravated by dampness and a high concentration of suspended particulate matter in the air.

Photochemical smog

• Photochemical smog is also known as “Los Angeles smog”.
• Photochemical smog occurs most prominently in urban areas that have large numbers of automobiles (Nitrogen oxides are the primary emissions).
• Photochemical (summer smog) forms when pollutants such as nitrogen oxides (primary pollutant) and organic compounds (primary pollutants) react together in the presence of SUNLIGHT. A gas called OZONE (Secondary pollutant) is formed.

Nitrogen Dioxide  +  Sunlight  +  Hydrocarbons  =  Ozone (Ozone in stratosphere it is beneficial, but near the earth’s surface it results in global warming as it is a greenhouse gas)

• The resulting smog causes a light brownish coloration of the atmosphere, reduced visibility, plant damage, irritation of the eyes, and respiratory distress.

Haze

• Haze is traditionally an atmospheric phenomenon where dust, smoke and other dry particles obscure the clarity of the sky (No condensation. Smog is similar to haze but there is condensation in smog).
• Sources for haze particles include farming (ploughing in dry weather), traffic, industry, and wildfires.

Effects of Smog

• The atmospheric pollution levels of Los Angeles, Beijing, Delhi, Mexico City and other cities are increased by inversion that traps pollution close to the ground.

It is usually highly toxic to humans and can cause severe sickness, shortened life or death.

• Smog is a combination of airborne particulate matter, like soot, and invisible toxic gases including ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2), which are carcinogens (cancer causing agents).
• Temperature inversions are accentuated and precipitation is reduced.
• Smog related Haze lowers visibility.

Our own publications are available at our webstore (click here).

For Guidance of WBCS (Exe.) Etc. Preliminary , Main Exam and Interview, Study Mat, Mock Test, Guided by WBCS Gr A Officers , Online and Classroom, Call 9674493673, or mail us at – mailus@wbcsmadeeasy.in
Visit our you tube channel WBCSMadeEasy™ You tube Channel
Please subscribe here to get all future updates on this post/page/category/website