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Pollution Radar Exposes Urban Smog

Scientists and industrials from the Surrey Satellite Technology Ltd, the University of Leicester and EADS Astrium have developed a air quality mesure device that can play the role of a pollution radar over cities. Dr Roland Leigh from the University of Leicester details the principle for Scitizen.

What technology does the pollution radar rely on?

CityScan, the pollution radar uses novel imaging spectrometers and high-speed CCD detectors to analyse scattered sunlight to an unprecedented level of detail. The software which turns this spectral information into 3D gas concentrations contains a number of complex algorithm components developed at the University of Leicester to correctly apportion gas concentrations to given locations. The imaging spectrometer has been designed by Surrey Satellite Technologies Ltd, and is a novel concentric design, originally proposed for the space industry, recently demonstrated in a lab at the University of Leicester, and now being integrated into this operational air quality monitoring system. The spectrometers separate the sunlight into individual wavelengths. The intensity of each wavelength, in each viewing direction is recorded on CCD detectors. These intensities are used to derive 3D gas concentrations. The high speed detector systems being used in this instrument are the result of 10 years of development at the University of Leicester in ground-based and space-borne detector electronics.

What are its advantages over currently available air quality measuring devices?

Current air quality monitoring devices measure the concentration of gases such as NO2 at a given location, usually by sucking air into an instrument. Such techniques provide accurate results for a given specific location, but do not in themselves accurately represent the widely variable concentrations over large urban areas. Usually models are employed in an attempt to fill in the gaps between these point measurements in a city. CityScan probes the whole atmosphere above a city, and takes measurements from every spot, allowing a direct measurement of concentrations of gases such as nitrogen dioxide. These measurements will allow us to directly measure emissions over particular areas, follow the transport of those emissions across the city, and to a certain extent, track the chemical changes in the air as it moves.

You are currently developing two new instruments to create 3D maps of atmospheric gases. To what extent may all these new tools contribute to a public health policy in cities?

These two instruments will provide information on emissions, transport and chemistry of air quality gases within an urban environment. For policy-makers, accurate maps of emissions across a city are a vital tool in decision making, coupled with an understanding of how these emissions behave downwind, both chemically and dynamically. The measurements CityScan offers can provide many extra pieces of information, to help policy makers identify and prioritise emission sources which may have an impact on air quality and the health of residents in particular areas of the city. Such information is key to decision makers when evaluating the societal benefit of the emitting processes against the potential harm of the resultant pollution.

Roland Leigh is a researcher at the Earth Observation Science, Space Research Centre, Department of Physics & Astronomy, University of Leicester.

Source Scitizen