9.8.2012 Project Clearflo to monitor air quality

London's most comprehensive attempt to measure and record air pollution in the capital is now underway – with 80 scientists from 11 universities monitoring nearly 1,000 different gases and particles in the atmosphere.

Project ClearFlo was timed to start during the Olympics, and intends to help improve air quality forecasting in years to come. Air quality is being examined at ground level, from the top of the BT Tower and using a research plane circling the capital.

Much of the capital's air pollution is generated from transport on the ground, which causes London to frequently exceed international air quality standards set by the EU and World Health Organisation. If limits are breached more than 30 days of the year, significant fines have to be paid to the EU.

It is important to study air quality as gases such as ozone, nitrogen dioxide and particulates are a well know cause of health problems, mainly respiratory related. However, one scientist said that many of the chemicals are not emitted directly by vehicles etc, but are formed during interactions between different pollutants when in the atmosphere, in the presence of sunlight.

One such interaction that is being monitored from a playground in Kensington is the chemical known as hydroxyl that is produced when sunlight hits ozone. Hydroxyl then acts as a catalyst to generate nitrogen dioxide – a toxic gas that causes many health problems.

The main reason for embarking into such a detailed analysis of London's air quality is so that forecasting times of high pollution can be made more accurate, and advice can be given for abatement in the future.

The technical instruments used during the project have previously been deployed all round the world, including Tasmania and Antarctica, by fitting them to shipping containers and vehicles. This has given the researchers a clear picture of what unpolluted air looks like – what is visible in London is very different!

A collection of data from the ground, London's BT Tower and Britain's largest atmospheric research plane will be collaborated to create a three-dimensional pollution image of what is known as the "London Plume" – a manmade cloud that rises over London. Major contribution to the plume comes from vehicles, heating boilers, domestic cookers and occasionally European industrial pollution.

The research aircraft flies very close to sea level along the south and east coasts around London. Scientists are able to analyse air the blows into London off the sea and air that blown out the other side. The difference between the two allows them to understand what is happening in the middle – what is added to the air over London.

A major aim of the project is to determine what portion of the air pollution above London is sourced in the capital itself, and how much of it is blown over from European industrial centres.

Dr Grant Allen of the University of Manchester explains that: "Part of this project is to assess whether we're breaking those limits because of the pollution generated in London itself or whether it's pollution that might be coming into the UK from the Continent."

Pollution over London during the Olympics so far has been at relatively low levels, but if temperatures rise and the sun starts to shine, pollution could quickly build up. For people that are vulnerable to respiratory problems, such as those with asthma, could benefit hugely from having an accurate forecast, something that ClearFlo aims to make possible.

BBC, Project Clearflo