Lack of daily data on airborne particles has been a common problem in an ai
r pollution research. To deal with this problem, a regression model was dev
eloped to estimate daily PM IO concentration using visibility in Bangkok fr
om 1992 to 1997, based on 1092 visibility/PM IO pair- observations on low h
umidity days (humidity less than or equal to 76.5%). Visibility was signifi
cantly and inversely associated with PM10 (r =0.71), after adjusting for mi
nimum temperature and winter indicator variable. The R-2 of the model was 0
.51.