Analysing air quality

Analysing air quality

Improving the quality of the air we breathe in our urban centres has become one of the most pressing problems for town and city authorities around the world. Anthony Smith explains how the new RapidAir® software from Ricardo provides a much-needed diagnostics and decision-support capability to help tackle the challenge of improving urban air quality
 
The link between air pollution and negative health outcomes for the inhabitants of towns and cities around the world – including increased mortality rates associated with respiratory illnesses – is now universally accepted. Increasing urbanization, industrial processes, and the effects of motor transport within the enclosed ‘urban canyons’ of densely developed cities, leads to local street-level concentrations of pollutants including oxides of nitrogen (NOx, and NO2 in particular), microfine carbonaceous particles, ozone and carbon monoxide.
 
The negative effect of this poor air quality for urban citizens is tangible. In the UK in August 2018, for example, the government sponsored Committee on the Medical Effects of Air Pollutants (COMEAP) published the results of a four-year project which estimated that between 28,000 and 36,000 premature deaths annually could be linked to longterm exposure to air pollution. City authorities have a wide range of policy levers at their disposal in order to help improve urban air quality, particularly with regard to the management of traffic flows and the mix of vehicle types that are permitted in different areas. But to be successful in delivering significant air quality improvement outcomes, such policy initiatives need to be based on reliable information about the distribution of concentrations of pollution across the city, and ideally include an understanding of its original source.
 

Limitations of monitoring

 
Roadside air pollution monitoring stations are used to great effect across the UK and other countries to monitor and report on local pollution levels. While the information obtained is extremely useful, it has its limitations too. Monitoring stations report the history of pollution but cannot predict when air quality is likely to change. Furthermore, they can only monitor a single location point, while air quality can change substantially over comparatively small distances.
 
“In areas surrounded by tall buildings, air pollution can become trapped, especially if the wind is blowing in a direction perpendicular to the urban canyon formed by the street,” explains Dr Nicola Masey, consultant for environmental evidence and data at Ricardo Energy & Environment. “We need to build on the air quality monitoring systems that are already in place across the UK and elsewhere – particularly in the larger towns and cities – and enhance the temporal and spatial extent and resolution information that we can provide to both the public and to policymakers.”
 

Introducing Ricardo RapidAir®

In order to address this requirement, Ricardo has developed its RapidAir® urban air quality diagnostics tool. Underpinned by the United States Environmental Protection Agency’s AERMOD modelling codes, RapidAir® includes an emissions model with up-to date, fully validated and peer reviewed emission factors, and supports modelling of emissions from all of the common source sectors – including transport, industry, construction, demolition and landfill. It facilitates fast and efficient city-scale air quality modelling and mitigation scenario testing for a comprehensive range of emission sources and pollutants. With spatial resolution down to one metre, and run times in minutes, the software enables policymakers to test and optimize complex air pollution  abatement strategies with unrivalled power and speed. As an operational air pollution tool, RapidAir® also provides advanced air quality diagnostics and ‘what if’ scenario testing capabilities.

Modelled pollutants include nitrogen oxides (NOx), NO2, sulfur dioxide (SO2) and carbon monoxide (CO) gases, as well as PM10 and PM2.5 ultrafine particles. In each case, the software can provide mass and volume concentration predictions over domains that range from individual streets to city, regional and national scales. RapidAir® also integrates local emissions, meteorology and measurements to ensure a complete representation of urban air quality.
 
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