Clearing the air

Global warming presents yet another air-quality challenge for cities

July 30, 2010 | By Andrej Klemenc

On June 1-2, 2010, 67 experts from 19 European countries, the European Environmental Bureau and US Environmental Protection Agency met in Ljubljana, Slovenia for a conference titled 'Getting Ready for the Future - Cities for Cities: Tools for Improving Air Quality and Tackling Climate Change'. The conference was opened by Slovenian State Secretary of Environment Zoran Kus, and organised by REC Slovenia within the framework by EU INTERREG V C and the EU Regional Development Fund-financed project CITEAIR II.

THROUGH THE HAZE: A layer of pollution hovers above Paris. Photo: Airparif
The event served as a forum for representatives from cities and research institutions to exchange views on approaches and tools to improve urban air quality, reduce greenhouse gases, and to provide real-time information to the public on the state of the environment. There was also discussion about the best ways to forecast urban air quality within one-day time horizons, as well as how to best approach emissions and greenhouse gases in an integrated way. Also introduced was the concept of a sustainable traffic and mobility indicator to benchmark traffic situations in urban agglomerations. In addition, city representatives from Munich and the province of South Holland demonstrated some practical activities for reducing air pollution.

Do we need to sound another alarm concerning urban air quality?

Air pollution is a problem today for the majority of EU cities. This is the case not just in industrial or Central and Eastern European cities, but also those in environmentally advanced countries, such as Stockholm, Sweden. The major concern is no longer industrial smog or smoke from residential chimneys, but ozone (03), nitrogen oxides (NOx), fine particles with less then 10 microns (PM10) and particles with even less than 2.5 microns (PM2.5) in diameter, which are originating from transport sector, especially from diesel-engines vehicles, factories, household wood burning, other modes of transport, and chemical reactions in the atmosphere.

Recent studies of the impacts of air pollution on public health are alarming: they show that exposure to air pollution lowers the average life expectancy of EU citizens by nine months. As scientific research provides more and more disturbing evidence, the problem of urban air pollution is reclaiming media attention after taking a back seat to the issue of climate change for roughly a decade. As the transport sector has emerged both as a source of GHG emissions and urban air pollution, there is now some overlap for identifying synergistic ways to tackle both problems at once.

Climate mitigation and air protection: synergies and trade-offs

However, apparent synergies between climate and air-protection measures also involve some trade-offs. Advanced diesel-fuelled vehicles are, for example, generate fewer CO2 emissions than gasoline engines at the same level of performance, but even when equipped with fine-particle filters, are not as clean. Whereas market penetration of electric cars would improve air quality in cities, it might lead to increased GHG emissions from thermal power plants. Conversely, an increased share of biomass in energy supply could, with a sustainable forestry and land-use management regime, provide CO2-neutral energy services; but, if burned in densely populated areas without deployment of expensive fine-particle and NOx-reduction technologies, would create substantial pollution.

On the other hand, an increased share of public transport in urban modal splits can provide net improvements in climate mitigation and air quality, even if public transport vehicles are not yet close to zero-emission capability. Energy efficiency gains are also win-win solutions, no matter at which level of energy transformation they occur.

To summarise, mitigation efforts aimed at reducing energy consumption result in both improved air quality and reduced GHG emissions. However, changes in energy supply must be carefully analysed beforehand to make sure that improvement in one area does not lead to deterioration in another areas.

Searching for new tools

It is therefore extremely important for national, regional and city authorities to have at their disposal tools that allow simultaneous monitoring and reporting of both greenhouse gases and pollutant emissions. Without integrating these inventories, authorities run the risk of failing to find optimal solutions to climate change and urban air pollution. Even worse, they could possibly exacerbate one problem in the attempt to solve the other.

The development of mobility indexes for cities is one way to achieve a better understanding of the complex relationship between transport and air quality, and yet another necessary tool for air quality and mobility management urban areas.

In order to avoid the worst direct impacts of air pollution, it is wise to target groups at highest risk from exposure, such as children, the elderly and those who suffer from cardiovascular diseases. City authorities also need improved air-quality forecasts in order to take pre-emptive emergency measures to avoid worst-possible outcomes.

Climatologists foresee increases in average temperature and greater frequency of heat waves due to global warming, which could in turn lead to higher ozone levels and more air pollution.

Raising citizen awareness

Parallel to an increased need for integrating emission inventories, new tools for air-quality forecasting and urban mobility management, is awareness-raising capacity of air quality among the citizens. The creation of a system to provide adequate, real-time and easy-to-understand information is a fundamental, permanent task.

Whereas the web portal serves as a source for several air-quality information services and activity groups in US states and cities, the CITEAIR II project is trying to increase the number of cities sharing comparable and accurate information on air quality via the website. Currently translated into French, Dutch and Spanish languages, translations into Croat, Macedonian, Polish, Slovene and Serb languages are to follow.

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