Although the deleterious effects of air pollution from fossil fuel combustion have been demonstrated in many Western nations, fewer studies have been conducted in Asia. The Public Health and Air Pollution in Asia (PAPA) project assessed the effects of shortterm exposure to air pollution on daily mortality in Bangkok, Thailand, and in three cities in China: Hong Kong, Shanghai, and Wuhan.

Poverty is a major determinant of population health, but little is known about its role in modifying air pollution effects. The researchers set out to examine whether people residing in socially deprived communities are at higher mortality risk from ambient air pollution.