M5L7: Air Pollution

Air pollution

We shift to the next culprit, that claims maximum lives in India. It is air pollution

Before going further, let us quickly go through certain basics

There are certain convection currents happening within the atmosphere. It happens this way

Now you must have heard about Temperature inversion

Inverse of 2/3 is 3/2

Inverse of 3/5 is 5/3

Thus, Numerator goes to bottom & denominator goes to the top. A similar event happens during Temperature Inversion. In this case, the colder air goes at the bottom & hot air stays at the top of it. This results in aggravating both the both industrial and photochemical smog as the winds can travel either horizontally or get pushed towards the ground

There are two types of SMOG

1.    Photochemical smog or Los Angeles-type smog or oxidizing smog

2.    Industrial smog or classical smog or London-type smog or Sulfurous smog or Reducing type smog

Los Angeles Smog

1.    Photochemical Smog is formed due to combustion products that are released from automobile and other instruments that release emissions through the burning of fossil-fuel. This smog, creates a dingy, brownish haze

2.    It occurs in hot & dry climates esp. on sunny days or at midday when sunlight is most intense.

3.    The primary pollutant in photochemical smog = NOx or VOC. Produces a host of secondary pollutants that result from a series of complex chemical reactions in the presence of UV.

4.   Ozone is the most important of these, but carbon monoxide and peroxyacetyl nitrates (PAN). Carbon monoxide leaches oxygen from the bloodstream, and PAN is an eye irritant. Thus, the more intense the Sunlight, the more noxious it feels.

London-type smog

1.    This 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.

2.    It occurs in foggy, cool weather typical of that experienced in the British Isles and the eastern seaboard of the United States.

3.    This smog is most intense in the early morning

4.    It casts a gray pallor over the areas it affects due to the presence of tar-laden droplets, formed by combination of coal dust and moisture.

5.    This smog also brings acid rain due to the high presence of Sulphur dioxide in it.

The smog becomes extremely hazardous during temperature inversion since the products of combustion are brought down closer to the ground. Hence people risk inhaling them in higher proportions, thereby putting themselves at risk. This is the hidden cost of fossil fuels and is already covered in Module 1

Another source of Particulate matter is cigarettes. In either way, both of them bioaccumulate in the lungs, leading to emphysema.

The lungs contain small pores, vital for exchanging impure air against pure air. When the pores get blocked, a person risks suffering from cardiac arrest due to emphysema.

To resolve this problem, engineers have come out with e-cigarettes. However, they are found to be more harmful than paper cigarettes as they produce a greater number of aerosols and free radicals.