Size–segregated particles in 59 elderly residences of São Paulo were measured.
The dominance of fine particles was found with PM<sub>2.5sub> contributing 78% of total PM<sub>10sub>.
Indoor sources dominated with I/O as 1.89 and 1.06 for PM<sub>2.5sub> and PM<sub>10sub>, respectively.
Respiratory deposition for PM<sub>2.5sub> was almost 25% higher in male than female elderly.
Dominance of fine particles suggests control of indoor sources in elderly residences.