[Model Answer QP2022 GS3] Discuss in detail the photochemical smog emphasizing its formation, effects and mitigation. Explain the 1999 Gothenburg Protocol.

Photochemical smog formation can be compared to a mixture of pollutants created when volatile organic compounds and nitrogen oxides interact with sunlight. 
As a result, they make a brownish haze that can be seen above the cities, usually in the summer months when there is lots of sun.

Primary and secondary pollutants

1. Primary pollutants include volatile organic compounds and nitrogen oxides. 
2. When they react with sunlight, they create secondary pollutants, meaning the ozone at ground level, or other harmful compounds like peroxyacetyl nitrate.

Formation of Photochemical Smog

Effects of Photochemical Smog

Pollutant Effects 
1. Nitrogen oxides can contribute to problems with heart and lungs.
links to decreased resistance to infection.
2. Volatile organic compounds (VOCs)eye irritation
respiratory problems
some compounds are carcinogens
3. Ozonecoughing and wheezing
eye irritation
respiratory problems (particularly for conditions such as asthma) 
4. Peroxyacetyl nitrate (PAN)eye irritation
respiratory problems

Mitigation: How can we reduce the occurrence of photochemical smog? 

Reduction of nitrogen oxide: The main method of lowering the levels of nitrogen oxides is by a process called ‘catalytic reduction’, which is used in industry and in motor vehicles. For example, a catalytic converter fitted to a car’s exhaust system will convert much of the nitric oxide from the engine exhaust gases to nitrogen and oxygen.
Reduction of VOCs : There are various ways to reduce VOC emissions from motor vehicles. These include the use of liquefied petroleum gas (LPG) or compressed natural gas (CNG) rather than petrol, decreasing distances vehicles travel by using other modes of transport, such as buses and bikes, and implementing various engine and emission controls now being developed by manufacturers.

The 1999 Gothenburg Protocol also know as Multi-effect protocol

1. Protocol to the UNECE (United Nations Economic Commission for Europe) Convention on Long-Range Transboundary Air Pollution (LRTAP)
2. The protocol aims to abate acidification, eutrophication and ground-level Ozone.
3. Protocol sets national emission ceilings for 2010 up to 2020 for four pollutants: sulphur (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs) and ammonia (NH3).
4. Commitments for 2020 and beyond for those pollutants as well as fine particulate matter (PM2.5) are included in the 2012 amended Gothenburg Protocol, expressed as a percentage reduction from 2005. 
5. Black carbon, a short-lived climate pollutant, was added as a component of particulate matter to the amended Protocol.
Doing our part and getting your community involved can help in reducing the impact of smog on your area. Attempt to reduce personal pollution output. Walk or bike to places that are short distances away instead of driving. Reduce electricity usage.Turn off lights, air conditioning and electronic devices when not in use. Arrange to be involved in a local car pool or use public transportation instead of driving.

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