New study argues household emissions are the key to reducing Beijing air pollution
The high levels of air pollution first came to global attention before the 2008 Beijing summer Olympics, when factories were ordered to halt production so as not to impact on the health of tourists, spectators and athletes. Today, the average daily concentration of the smallest particulates (able to lodge deeply in the lungs and cause chronic and acute respiratory illness, heart disease and lung cancer) is more than 6 times the recommended safety limited as stated by the World Health Organisation (WHO). Levels of other major pollutants, such as ozone, are also dangerously high. Partly financed by the EU-funded PURGE (Public Health Impacts in Urban Environments of Greenhouse Gas Emissions Reductions Strategies) project but led from UC Berkeley’s School of Public Health, Princeton University, and Peking University, the study discovered that by narrowly focusing on curbing pollutants within Beijing and its suburbs, rather than the larger region, could limit the potential effectiveness of pollution-control efforts. The study will be published shortly in the highly regarded journal ‘Proceedings of the National Academy of Science’. ‘You cannot have a clean outdoor environment if a large percentage of the population is burning dirty fuels in households several times a day,’ commented Prof. Kirk Smith of UC Berkeley. ‘The smoke may start indoors, but soon leaves the house and becomes a significant part of regional air pollution.’ The modelling study conducted by the researchers is the first to incorporate local and regional datasets on air emissions and combine these with modelling of weather impacts and atmospheric chemistry in the region to devise estimates of the impact of household emissions during the winter months, when heating demands are greatest. The research team argues that emission reductions from the residential sector could have greater air-quality benefits in the North China Plain, which includes Beijing, than reductions from other sectors. China’s 5-year plan to address continuously high air pollution in the Beijing region did not take household emissions into account and has focused on industrial-level emissions. In particular, the researchers used the Weather Research and Forecasting Model with Chemistry, a model developed in the US and used by researchers worldwide to generate atmospheric simulations using real data from China. They focused their efforts on Beijing, Tianjin and Hebei provinces, which have a combined population of more than 100 million. They then made estimates of the relative contributions of emissions sources using data from 2010, and also modelled emissions reductions scenarios to derive estimates for reduction levels of small particles over the region that would result from different mitigation efforts. The researchers concluded that eliminating household emissions alone would reduce the levels of small particulate pollution in Beijing during the wintertime by around 22 %, but that eliminating household emissions in all three provinces surrounding Beijing would nearly double the reduction in particulate levels in the city itself. In other words, according to Smith, Beijing cannot itself act alone to control pollution levels and the research has highlighted the importance of regional cooperation. ‘On a smaller scale, here in the [San Francisco] Bay Area, air-quality control is not only focused on San Francisco and Oakland, but also coordinated across nine Bay Area counties through a regional governing body,’ Smith said. Importantly to note, the research team did not attempt to evaluate how climate change might be affected by Chinese efforts to reduce household burning of biomass fuel by supplying natural gas. Nor did the researchers try to better understand the health benefits of reducing household emissions. For more information please see: project website
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