© 2026 LearnInShort
Pollution is the addition of any substance or energy to the environment at a rate faster than it can be dispersed, broken down or absorbed. The substance doing it is a pollutant.
Almost every question from this chapter is one of three kinds, and knowing which kind you are looking at saves most of the work.
The first kind asks which substance — which gas causes acid rain, which metal caused a named disease, which pollutant an index measures.
The second asks a number — what a reading on the air quality index means, what unit noise is measured in, what a high value of biochemical oxygen demand indicates.
The third asks a treaty or an institution — which protocol deals with the ozone layer, which agreement replaced which, which year a board was set up.
So do not revise this chapter as prose. Revise it as three short lists: substances, numbers, and agreements with their years.
SSC CGL and CHSL, RRB NTPC, BPSC TRE-4 general studies, UPSC Prelims and CTET environmental studies all draw on it, and it is one of the few chapters where all five ask at roughly the same depth.
1. On India's Air Quality Index, a reading of 150 falls in which category?
2. A high Biochemical Oxygen Demand (BOD) value in a water sample indicates what?
3. Minamata disease is caused by poisoning from which metal?
4. Which international agreement, adopted in 1987, deals with phasing out ozone-depleting substances?
5. Eutrophication of a lake is caused mainly by what?
6. Noise level is measured in which unit?
7. Which body, set up in 1974, is India's apex authority for monitoring and controlling pollution?
8. What temperature goal does the Paris Agreement of 2015 set?