Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are produced.

What has been done?

1970 was the worst year for air pollution in the UK with over 6 million tonnes of sulphur dioxide being released.  In 1973 and 1979 there was a noticeable jump in emissions due to cold winters and a greater need for heating in our homes, shops and work places. 

Governments around the world have placed restrictions on sulphur-emitting processes, making it illegal to cause high emissions. Introduced across Europe on 1 January 2008, the Large Combustion Plant Directive (LCPD) aims at reducing sulphur emissions.  In 2013 the Industrial Emissions Directive (IED) came into force. This legal agreement combines seven existing Directives, including the LCPD. The large combustion plants that produce our energy need to meet IED requirements by 2016. See UK's Air Polution Information System for more details.

The 1999 Gothenburg Protocol set limits on emissions and came into force in 2010.  Unfortunately international agreements failed to include shipping which uses sulphur rich fuels that are now banned on land, so emissions from the North sea could still reach countries such as Norway.  However, in July 2011 the European Commission proposed to reduce sulphur emissions from the fast-growing maritime and shipping industry by 90% by limiting the legal sulphur content allowed in fuels in certain areas such as the Channel and Baltic Sea.

The International Marine Organisation (IMO) works to limit the sulphur content of shipping fuel used with Emission Control Areas (ECAs). The ECA cap was reduced to 1% m/m, with a further reduction to 0.10% effective from 1 January 2015.

Whilst many countries have reduced their emissions, an upsurge in industrialisation and reliance on fossil fuels in countries such as China could lead to a further increase in sulphur dioxide emissions.

Read More: What about nitrogen?

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