heat stroke is associated with prolonged exposures to high air temperatures that usually occur in the summer months of july and august in tokyo , japan . 
 also during july and august , residents of tokyo are often exposed simultaneously to high concentrations of air pollutants . to assess the impacts of these combined exposures , daily numbers of heat stroke emergency transport cases / million residents for tokyo were stratified by gender and three groups : 0 - 14 , 15 - 64 ; and > 65 years of age , for the months of july and august in 1980 - 1995 . 
 a regression model was constructed using daily maximum temperature ( tmax ) and daily average concentrations of no2 and o3 as model covariates . 
 classification indices were added to make it possible to compare the expected number of heat stroke cases by age and gender . 
 lag times of 1 - 4 days in tmax and air quality covariates and terms to account for interactions between pairs of model covariates were also included as additional risk factors . 
 generalized linear models ( glms ) , assuming a poisson error structure for heat stroke emergency transport cases , were used to determine which covariates were significant risk factors for heat stroke for the three age groups of males and females . 
 same - day tmax and concentrations of no2 were the most significant risk factors for heat stroke in all age groups of males and females . 
 the number of heat stroke emergency transport cases / million residents was greater in males than in females in the same age groups . 
 the smallest number of heat stroke emergency transport cases / million residents occurred for females 0 - 14 years of age and the greatest number of heat stroke emergency transport cases / million residents occurred for males > 65 years of age.imagesfigure 1figure 2figure 3figure 4figure 5