The objectives of this study were to assess potential health and productivity benefits for the year 2010 with five scenarios for reducing particulate matter (PM10 and PM2.5) air pollution in the cities of Osaka, Houston, Bangkok and Seoul. Assuming a uniform 10% decline in ambient PM levels, the preventible cases of: (1) premature mortality ranged from 35 in Houston to 379 in Seoul, (2) chronic bronchitis ranged from 95 in Houston to 1,631 in Seoul, (3) cardiovascular disease ranged from 68 in Houston to 818 in Seoul, (4) pneumonia ranged from 28 in Houston to 336 in Seoul, (5) asthma attacks ranged from 388 in Osaka to 96,876 in Seoul, and (6) acute bronchitis ranged from 186 in Houston to 2,973 in Seoul. The per million population central estimate of the purchasing power parity adjusted value of health and productivity benefits ranged from $25 million in Bangkok to $160 million in Osaka. There was a wide variability in measured PM10 levels across cities. Percentages of active monitors reporting concentrations above 50 µg/m3 (annual average) or 150 µg/m3 (24-hour average) in 2001–2002 were 0% in Houston, 5% in Osaka, 33% in Bangkok and 92% in Seoul. Assuming a non-uniform reduction in PM only at concentration hotspots with levels above air quality standards, the number of preventible cases of mortality ranged from 0 in Houston to 1,104 in Seoul. The central estimate of total benefits ranged from $0 in Houston to $240 million in Seoul.