Ne­far­i­ous ni­tro­gen

Down to Earth - - ANALYSIS -

WHILE NI­TRO­GEN com­pounds po­ten­tially pol­lute ev­ery el­e­ment of our ecosys­tem, air is the most crit­i­cal medium in terms of dam­age through ni­tro­gen pol­lu­tion. Agri­cul­ture, trans­port, energy pro­duc­tion and com­bus­tion in in­dus­try con­trib­ute to emis­sions of ni­tro­gen pol­lu­tants into the air.

The re­lease of am­mo­nia and ni­tro­gen ox­ides into the lower at­mos­phere has sig­nif­i­cant health im­pacts. Ni­tro­gen ox­ides are formed through a com­bi­na­tion of ni­tric ox­ide and ni­tro­gen diox­ide. These two ni­tro­gen com­pounds form fine par­tic­u­late mat­ter (PM) that has been noted to be a sig­nif­i­cant con­trib­u­tor to­wards lung dam­age, res­pi­ra­tory ail­ments and re­duc­tion of life ex­pectancy. Ni­tro­gen ox­ides also cause pho­to­chem­i­cal smog in which high level of tro­po­spheric ozone is pro­duced. This ozone, which is closer to the Earth's sur­face, is harm­ful for both hu­mans and the en­vi­ron­ment. It has been found to cause ad­verse short-term and chronic im­pacts on res­pi­ra­tory func­tions. It is detri­men­tal to agri­cul­ture and causes dam­age to crop pro­duc­tion of up to five per cent ev­ery year glob­ally.

Ni­trous ox­ide (N O), another ox­ide of ni­tro­gen, is a green­house gas that is 300 times more re­ac­tive than car­bon diox­ide and has a life­span of 120 years in the at­mos­phere. An Amer­i­can study in 2012 found that over a pe­riod of 100 years, the heat­ing ef­fects of N O far out­weighed any short-term cool­ing im­pact that re­ac­tive ni­tro­gen might have. Fur­ther, N O has a po­ten­tial of ozone de­ple­tion in the strato­sphere— this ozone pro­tects us from the harm­ful ul­tra­vi­o­let rays of the sun—that is com­pa­ra­ble to the po­ten­tial of hy­drochlo­roflouro­car­bons which were phased out in the 1990s as a highly ozonede­plet­ing sub­stance.

Ni­tro­gen can be blamed to a large ex­tent for In­dia's poor air qual­ity. Ac­cord­ing to media re­ports, 13 of the 17 most pol­luted cities in the world are in In­dia. Delhi and Kolkata far ex­ceed the World Health Or­ga­ni­za­tion's (WHO's) stan­dard of 40 mi­cro­grams per cu­bic me­tre for N O. Chen­nai and Ben­galuru are the only metro cities that are safely within pre­scribed lim­its. Twenty-seven In­dian states, for which data is avail­able, ex­ceed the WHO limit of 20 mi­cro­grams per cu­bic me­tre for an­nual mean PM.

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