One consequence of the spring and summer floods of 1993 has been an en
ormous number of water damaged homes in the upper midwestern United St
ates. A team of investigators with a variety of skills was assembled t
o monitor the effect of various cleaning, disinfecting, and drying str
ategies on indoor air quality of two flood damaged homes over one year
's time. Additionally, six flooded homes in Marshall, Minnesota, were
monitored twice, at seven and 17 months after flooding. One component
of the home study was periodic measurement of indoor mold spore levels
. Measurements in all homes indicated that elevated mold levels persis
ted long after homes were cleaned and dried. While ambient levels thro
ughout the homes tended to return to normal after about a year, pocket
s of contamination remained at the end of the study. Although no compa
rable pre-flood data are available, these results suggest that more ef
fective decontamination procedures may be needed to prevent subsequent
mold problems in flood damaged homes.