Skip to navigation
Skip to content

Urban Air quality

Air quality: particulate pollution, photochemical smog and pollution reduction policies.

The quality of air within urban areas is often of a much poorer quality than that of surrounding rural areas. This is particularly pronounced in industrial cities and in cities within LICs and LDCs where environmental standards applied to heavy industries and vehicles are much lower than in richer nations.

This is important because;

  1. 40,000 early deaths a year (2015) are linked to outdoor air pollution in the UK, say the Royal Colleges of Physicians and of Paediatrics and Child Health. 1
  2. 6.1 million global premature deaths occurred due to air pollution in 2017 according to a report into State of Global Air 2018. 2

Particulate air pollution is a mixture of solids and liquid droplets floating in the air. Whilst Photochemical pollution is air pollution containing ozone and other reactive chemical compounds formed by the action of sunlight on nitrogen oxides and hydrocarbons, especially those in automobile exhaust.

Types of pollutants

The major difference between urban and rural areas is the use of fossil fuels, which produces lots of waste gas and particulate matter such as;

  • Particulate matter – this is fine grade material that can cause damage to human lungs, it is effectively the smoke and dust particles in the air. PM10 is the part of suspended particles that are only 10(µM) micrometres in size.
  • Carbon Monoxide (CO) – a poisonous gas to human beings, it is highly dangerous because it is colourless and odourless • Sulphur oxides e.g. SO2 & SO3 – these are given out during the combustion of fossil fuels, they often mix with water in the atmosphere to give Sulphuric acids
  • Carbon dioxide (CO2) – the most talked about pollutant, this gas can cause human enhanced global warming
  • Ozone (O3)– this gas protects in the upper atmosphere, but is dangerous to humans when it occurs in high concentrations at ground level in the Troposphere
  • Nitrogen Dioxide (NO2) – these cause the brown haze above of cities Particulates are the deadliest form of air pollution due to their ability to penetrate deep into the lungs and blood streams unfiltered, causing permanent DNA mutations, heart attacks, and premature death.

These gasses can be found in huge concentrations in city areas compared to countryside areas, the most dramatic being SO2, which can be found in concentrations 200 times greater than rural concentrations. Problems can be particularly pronounced in temperature inversions and during anticyclones, when air is prevented from rising which allows pollutants to build up in the lower atmosphere. There is a clear geographic pattern shown on the map3, the safe level that should not be exceeded is 20 (µg/m3), and it is clear that in LICs, and LDCs there are major problems.

World map pm 2.5

World map of PM 2.5 concentrations

Problems caused by poor air quality

As a native of Middlesbrough, I am well aware of the problems caused by the atmospheric pollutants above. In the North East of England, residents of my hometown are known as smogmonsters (!) because of the atmospheric pollution caused by the chemical and steel industries associated with Middlesbrough and Teesside. Smog is a mixture of smoke and fog; and can be particularly dangerous. Smoke and sulphur dioxide from burning are condensation nuclei, and in the past in Britain and currently in Industrialising economies these extra nuclei encourage condensation at ground level which produces dense fogs. London was badly affected by “pea soups” in the past, huge smogs which covered larges areas and caused large scale disruption to our nation’s capital. The worst case was in 1952, when an anticyclone settled over London for over 5 days in December. This descending air caused a temperature inversion, the air was unable to disperse in the sheltered Thames basin and a fog developed as water vapour condensed on soot and coal dust. Over 12,000 people died, many from respiratory problems and a small number fell into the Thames, as a result of this thick fog. 4

The diagram shows some of the problems posed by atmospheric air pollution by the UK government5;

Sources of air pollution UK

Air pollution in London

London suffers from air pollution, mainly due to the sheer size of the city, a dense road network and high buildings. This means that central London tends to be one of the most polluted places in the UK. London has failed many of the standards set by the EU and pollution can build up in London when anticyclones bring settled weather. London has problems with the following pollutants;

  • Ozone pollution in spring and summer, this gas is a poison to the human body
  • Particulate matter – these are tiny particles of solids or liquids suspended in the air. They come from carbon emissions from engines, small bits of metal and rubber from engine wear and braking as well as dust from road surfaces. They can come from natural sources and from building and industry. The tiny particles, referred to as PM10, can settle in the airway and deep in the lungs and cause health problems, premature death and the worsening of heart and lung disease.
  • Nitrogen Dioxide from burning fossil fuels in cars and central heating boilers is another problem gas. It is harmful to human health giving respiratory problems such as shortness of breath and coughing. It can also lead to lung infections such as bronchitis.6

Management of air pollution in London

London is working hard to try and protect people and clean up the air by;

a. Offering a free to download app that informs people of air quality

b. Cleaning up London's bus fleet by making them less polluting

c. Introducing a congestion charge in central London to reduce traffic volumes

d. Set new and tighter standards for the London Low Emission Zone

e. Invest record amounts of money in cycling and working with Sustrans Reducing pollution in UK cities

The UK is party to many international agreements concerning air pollution, and has its own internal laws and policies concerning the quality of air. Cars must have emissions tests on an annual basis as part of the MOT whilst industries are obliged to protect the environment as part of strict laws.

The Clean Air Strategy for the UK sets out air quality standards and objectives for reducing levels of health threatening pollutants. All of the standards under this are subject to regulations under the Environment Act of 1995 and are the result of UK incorporation of European Union laws. This act focusses on air pollution from farming, industry, transport and the home. Since December 1997 all local authorities in the UK have to review and assess air quality in their area. If any standards are being exceeded, then an area is designated an Air Quality Management Area (AQMA) and the local authority (Newcastle City Council for example) must make and implement an action plan designed to reduce levels of the pollutant. Domestic or home fires are also strictly controlled as part of the Clean Air Act of 1993, and Local Authorities can declare an area a Smoke Free Zone. Under this order, homes are banned from using fires that cause smoke unless they use smokeless fuel, or the appliance is exempt. Around 50% of households live in Smoke Free Zones in the UK.

Industries

Industries are also controlled. They are regulated under Integrated Pollution Prevention and Control (IPPC) set up under the Pollution Prevention and Control Act of 1999. It is an offence for factories to emit dark smoke under the Clean Air Act of 1993, except under unavoidable circumstances (e.g. lighting up). The amount of grit and dust emitted is also strictly controlled, and chimneys must have the most modern filters fitted.

Mumbai

Mumbai also has some very dirty air including dangerous levels of Nitrous Oxides and small dust particles called particulate matter. These are both hazardous to human health and can cause things like asthma. The causes of this pollution are industry, ever increasing numbers of cars and construction dust.

NEXT TOPIC -Urban Drainage

SOURCES

1 - Michelle Roberts (2016) - UK air pollution 'linked to 40,000 early deaths a year, BBC. Accessed 12th January 2020 from https://www.bbc.co.uk/news/health-35629034

2 - Health Effects Institute. 2018. State of Global Air 2018. Special Report. Boston, MA: Health Effects Institute. Accessed 12th January 2020 from https://www.stateofglobalair.org/sites/default/files/soga-2018-report.pdf

3 - National Community Mapping Institute - PM 2.5 Data. Accessed 12th January 2020 from http://communitymappingforhealthequity.org/pm-2-5-data/

4 - Christopher Klein (2012) - The Great Smog of 1952, History. Accessed 11th January 2020 from https://www.history.com/news/the-killer-fog-that-blanketed-london-60-years-ago

5 – Department for environment, food and rural affairs (2019)- CLEAN AIR STRATEGY 2019 - Accessed 11th January 2020 from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/770715/clean-air-strategy-2019.pdf

6 - https://www.london.gov.uk/priorities/environment/breathe-better-together/air-pollution-the-facts

 

Uploaded by Rob Gamesby April 2020

Search


Ads

Visits