Atmospheric Pollutants and Their Effects
Pollutants from Fuels
When fossil fuels are burned, several pollutant gases can be released into the atmosphere. The type and amount of pollutant depends on the fuel and the conditions of combustion.
The main pollutants are:
- Carbon dioxide (\(CO_2\)) — produced by complete combustion of any hydrocarbon. A greenhouse gas that contributes to global warming.
- Carbon monoxide (\(CO\)) — produced by incomplete combustion. A toxic, colourless, odourless gas that binds to haemoglobin in the blood, preventing it from carrying oxygen. Can cause death.
- Soot / particulates (carbon particles) — also from incomplete combustion. Cause respiratory problems, make buildings dirty, and contribute to global dimming (blocking sunlight).
- Sulfur dioxide (\(SO_2\)) — produced when fuels containing sulfur impurities are burned. Causes acid rain, which damages buildings (corrodes limestone/marble), kills trees and acidifies lakes.
- Nitrogen oxides (\(NO_x\)) — formed when nitrogen and oxygen react at the high temperatures inside car engines. Also cause acid rain and respiratory problems.
Fossil fuel pollutants: \(CO_2\) (greenhouse gas), CO (toxic), soot (respiratory problems), \(SO_2\) (acid rain from sulfur impurities), \(NO_x\) (acid rain from high temperature reaction of \(N_2\) and \(O_2\)).
Reducing Pollution
Catalytic converters in car exhausts convert toxic carbon monoxide and nitrogen oxides into less harmful gases:
$$2CO + 2NO \rightarrow 2CO_2 + N_2$$
Flue gas desulfurisation removes \(SO_2\) from power station emissions by reacting it with calcium oxide or calcium carbonate, producing calcium sulfate (which can be used to make plaster).
Solutions: catalytic converters reduce CO and \(NO_x\), flue gas desulfurisation removes \(SO_2\). Using low-sulfur fuels, renewable energy, and electric vehicles also reduces pollution.
Air pollution is a global issue. Pollutants can travel long distances in the atmosphere, meaning emissions in one country can cause acid rain in another. International agreements (such as the Paris Agreement) aim to reduce greenhouse gas emissions. Developing countries face challenges balancing economic growth with pollution reduction.
Alternative approaches to reducing pollution include: switching to renewable energy sources (wind, solar, hydroelectric), using electric or hydrogen-powered vehicles, improving fuel efficiency, and developing carbon capture and storage technologies.