Study finds that under business-as-usual scenario, average global air quality to worsen; China, North India and Middle East are the hot spots
|Population-Weighted Multi Pollutant Index (PW-MPI) values for different regions. Source: Pozzer et al.|
Under a business-as-usual (BAU) scenario, a rapidly increasing number of people worldwide will experience reduced air quality by 2050, according to a new simulation of the atmosphere done by scientists at the Max Planck Institute for Chemistry, the Institute of Atmospheric Physics and the Joint Research Centre of the European Commission. China, North India and the Middle East are expected to be especially affected by a drastic decrease in air quality.
Following this BAU scenario, the researchers projected that air quality for the global average citizen in 2050 would be almost comparable to that for the average citizen in East Asia in the year 2005—an outcome which underscores the need to pursue emission reductions, according to the authors.
Even though air quality will deteriorate further in North America and Europe, in 2050 it will be significantly better than that experienced by the global average citizen. Remarkably, the global PW-MPI in 2050 is projected to be similar to that in the Middle East in the year 2005. It should be emphasized that this result is strongly influenced by the high population density in Asia (i.e. poor air quality affecting a large number of people). In fact, East and South Asia both have the highest MPI values and the highest population densities.—Pozzer et al.
The team used a population-weighted multi pollutant index (PW-MPI), suited for global model output, with the atmospheric chemistry general circulation model EMAC to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050).
The emission scenario assumes that population and economic growth largely determine energy and food consumption and consequent pollution sources with the current technologies (“business as usual”). The BAU scenario assumes no further implementing legislation to prevent additional climate change and growing air pollution, other than what is in place for the base year 2005.
The authors said their study is the first to include all five major air pollutants known to negatively impact human health: nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and particulate matter smaller than 2.5 micrometers which are regarded as particularly harmful.
The open-access study, published in the current issue of Atmospheric Chemistry and Physics, a journal of the European Geosciences Union, finds that East Asia will be exposed to high levels of nitrogen dioxide, sulphur dioxide and fine particulate matter (PM2.5). Northern India and the Arabian Gulf region, on the other hand, will suffer a marked increase in ozone levels. This is primarily due to population density and the expected increase in industrial production and transport in these areas.
Air pollution in Europe and North America would also increase, but—due to the effect of mitigation policies that have been in place for more than two decades—to a much lesser extent than in Asia.
Subsequent to these results the researchers want to broaden the analyses. In the near future they want to calculate how many people would actually be affected by the harmful effects of deteriorating air quality.
A. Pozzer, P. Zimmermann, U.M. Doering, J. van Aardenne, H. Tost, F. Dentener, G. Janssens-Maenhout & J. Lelieveld (2012) Effects of business-as-usual anthropogenic emissions on air quality Atmos. Chem. Phys. Discuss., 12, 8617-8676, doi: 10.5194/acpd-12-8617-2012