Indoor, outdoor, and personal nitrogen dioxide (NO₂) exposures were studied in a population of housewives. Daily Indoor and outdoor NO₂ concentrations were measured and compared with simultaneously personal exposures of 17 housewives for 7 consecutive days in 17 houses. In this study, indoor and outdoor NO₂ samples at home were collected only while the housewives were at home samples. Time activity patterns and house characteristics were used to determine the effects of these factors on personal exposure. Since housewives spent their times in indoor houses with mean of 78.3%, their NO₂ exposures were associated with indoor houses NO₂ levels (r= 0.89) rather than outdoor NO₂ level (r= 0.85). Contribution of indoor NO₂ concentration on personal exposure was estimated by 70.77% by using of mass balance model. The close association between measured indoor NO₂ concentrations and measured personal exposure and contribution of indoor NO₂ concentration suggests that measuring indoor concentrations of NO₂ in the home is sufficient to estimate personal exposure accurately.