Air

The Pollution Team operates several monitoring programmes for a range of pollutants, some of which have been running for over 30 years. Currently the section monitors for nitrogen dioxide, ozone, carbon monoxide, fine particulates and hydrocarbons at various sites across the borough.

The Environment Act places a duty on Local Authorities to assess air quality throughout their area against air quality standards, declare Air quality Management Areas (AQMAs) where air quality is worse than the standard, and take action to improve air quality.

The Pollution Team operates 2 automated air Pollution Monitoring Stations, Hackney 4 at Brooke House Hackney Community College on Kenninghall Road  which measures:

Fine Particles (PM2.5)
Oxides of Nitrogen (NOx)
Ozone (O3)
Carbon Monoxide (CO)

And Hackney 6 at Old street near the fire station which measures:

Fine Particles (PM10)

Oxides of Nitrogen (NOx)

The Polluion Team also measures air quality at 12 other sites using diffusion tubes to measure Nitrogen Dioxide and Hydrocarbons including Benzene.

In May 1997 the Government produced the National Air Quality Strategy (NAQS). The strategy represents a comprehensive approach to maintaining and improving the quality of ambient air in the United Kingdom.

Outlined in the strategy are the air quality objectives for the 8 pollutants the Government feels are of most concern at present and the dates it feels these targets should be met. These objectives are shown in the table below.

PM10 Particulates

PM10 describes the fraction of airborne particulate matter that is less than 10 microns in size. Fine particles are of the greatest concern since they are capable of being easily transported over long distances on currents of air. Also, fine particles may be drawn into the respiratory airways where they may adversely affect health. Recently, the attention of scientists has been drawn towards studying the PM2.5 fraction and even smaller particles, which can penetrate the very deepest parts of the lung.

PM10 and other particulate matter may vary considerably in chemical and physical composition. The principal sources of these particles are combustion processes, including traffic and industry.

Nitrogen Dioxide (NO2)

Nitrogen dioxide is one of a number of nitrogen oxides, which are formed during high temperature combustion processes. Road traffic is the main source, accounting for approximately 50% of all European emissions. Therefore, concentrations tend to be highest in urban environments with high traffic levels. Large industrial sources can also have a significant impact.

Nitrogen dioxide is a respiratory irritant and also plays a part in the production of another atmospheric pollutant, Ozone. Nitrogen oxides remain in the atmosphere for approximately one day before they are oxidised to nitric acid. Nitrogen oxides are therefore a contributory factor in the production of acid rain.

Ozone (O3)

Ozone is a very reactive chemical, which is potentially toxic to both plants and animals. In the Stratosphere, ozone helps to protect the earth from the harmful effects of ultra-violet rays from the sun. However at ground level it is a pollutant. Unlike the other pollutants mentioned above, ozone is not emitted directly. Rather, it is formed as a result of a complex series of reactions involving hydrocarbons, sunlight and nitrogen dioxide (NO2). The involvement of sunlight in this process means that ozone levels tend to be highest in summer. The reactions take time to generate ozone and the highest concentrations are frequently experienced many miles away from the source of the pollution, perhaps in rural areas. In fact, a significant proportion of ozone incidents experienced in the UK are due to pollution imported from abroad. The problem of ozone pollution can therefore only be adequately dealt with as a result of international agreements.

Carbon Monoxide (CO)

Carbon monoxide is a colourless, odourless and tasteless gas that is produced in the process of combustion, such as the burning of fossil fuels or in a car engine. It is the most dangerous of all the pollutant gases and can cause death in very high concentrations. Once emitted into the atmosphere CO is slowly oxidised to CO2.

Vehicle emissions are again a major contributor. CO is produced by the incomplete combustion of fossil fuel. The main source of outdoor exposure (aside from smoking) is general pollution from vehicle exhausts, although indoor sources can account for a larger proportion than traffic.

Benzene

Benzene is one of a number of hydrocarbons for which long-term exposure to benzene has been linked to leukaemia and cancer.

The main sources of benzene in the UK are emissions from petrol-engined vehicles, petrol refining and the uncontrolled emissions from petrol stations where vapour recovery systems have not been fitted.

A number of measures in place have reduced emissions and will reduce emissions further in future years: Since 2000 the maximum benzene content of petrol has been reduced to 1%, and the European auto-oil programme will further reduce emissions from cars and light goods vehicles. The Pollution Team also monitors other hydrocarbons of concern including: toluene, xylene ethyl benzene and polycyclic aromatic hydrocarbons (PAH).

Air Quality Management

The Environment Act 1995 requires local authorities to carry out reviews and assessments of the air quality in their area to determine whether current or future air quality is worse than health based objectives for the pollutants; carbon monoxide, benzene, 1, 3-butadiene, nitrogen dioxide, lead, sulphur dioxide and fine particles.

Where the local authority is satisfied that the levels of air pollutants will continue to exceed the objective by the deadline for achievement the authority must declare an Air Quality Management Area and draw up an action plan to work towards achievement of the objectives.

The authority must then produce periodic action plan progress reports and updating and screening assessments.

Hackney’s Stage 1 review was completed in 1999 Stage III review and assessment was carried out in 2002, and Members subsequently declared Air Quality Management Areas (AQMAs) in the south of the borough and along major roads in 2002.

Hackney’s Air quality action plan and the Review and assessment (stage 4) was drafted in Feb. 2004 and consulted upon. Work is progressing to finalise and bring the plan up to date.

The updating and screening assessment re-assessed all seven pollutants was completed in August 2004. It concluded that for carbon monoxide, benzene, 1, 3-butadiene, lead, and sulphur dioxide, air quality in Hackney was better than the government’s standards.

Air quality monitoring data for Hackney’s automated sites can be found under Useful Websites.

pollution-bulletin-jan-2008.doc

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Page updated: 14 Oct 2008