Environmental Science (3110007)

BE | Semester-1   Winter-2019 | 16-01-2020

Q3) (b)

Give classification of Air pollutants.

The air pollutants can be classified on the following basis:

Classification based on origin

According to the origin air pollutants can be classified into Primary air pollutants and Secondary air pollutants.

Primary air pollutants
Primary air pollutants are emitted directly from the sources and are found in the atmospheres in the form in which they were emitted.
For Example SO2, NO2, HC, ash, smoke, dust, mist etc.
Secondary air pollutants
Secondary air pollutant are formed in the atmosphere by chemical interactions between primary pollutants and atmospheric constituents.
For Example Ozone, Sulphur trioxide, PAN, aldehydes, ketones etc.

Classification based on state of matter

According to the state in which air pollutants are found in atmosphere, they are classified as Gaseous air pollutants and Particulate air pollutants.

Gaseous air pollutants
Gaseous air pollutants are those air pollutants which are found in the gaseous state at normal temperature and pressure in the atmosphere.
For Example SO2, NO2, HC, CO, CO2 etc.
Particulate Air pollutants
These include suspended droplets, solid particles or their mixtures in the atmosphere, commonly referred as particulates.
For Example aerosols, dust, smoke, fumes, mist, fog, Flyash, soot, and natural particulates such as pollen grains, protozoa, fungal spores and volcanic dust.