Let's start with sources:
China air quality standards: The target for ambient air in urban areas in China is the National Grade II Standard, which is specified by National Standard GB 3095-1996, first issued in 1996 and then updated in 2000 (surprisingly, the update actually created less stringent air quality targets for certain pollutants).
United States air quality standards: The US EPA specifies air quality targets in the National Ambient Air Quality Standards (NAAQS).
WHO air quality standards: International WHO air quality guidelines were issued in 2005, replacing the European-focused standards published in 2000. The 2005 WHO guidelines include both ideal targets as well as interim targets for developing countries. For comparison, I have included here both the final targets and the Interim Targets 1.
Pulling numbers from each of the above sources, I created the following table:
1) China lacks an 8-hour standard for Ozone as well as any standards for PM2.5, though monitoring and reporting of these is supposedly going to begin this year.
2) Although the US EPA's PM10 standards do not appear very stringent, this is because the US EPA has prioritized limiting PM2.5 concentrations (which cause greater health impact) instead.
3) China's air quality standards are not as stringent even as the WHO's suggested Interim Targets 1.
These targets are proposed [by the WHO] as incremental steps in a progressive reduction of air pollution and are intended for use in areas where pollution is high. These targets aim to promote a shift from high air pollutant concentrations, which have acute and serious health consequences, to lower air pollutant concentrations. If these targets were to be achieved, one could expect significant reductions in risks for acute and chronic health effects from air pollution. Progress towards the guideline values should, however, be the ultimate objective of air quality management and health risk reduction in all areas.I have heard a rumor that China will revise its air quality standards this year; if and when they do, I am curious to know how aggressive the new targets will be.