In rooms 1 and 2, an increase in airborne A. fumigatus
conidia was recorded on 31
st
October 2008. The same day,
this fungus was also detected in the airborne sample from
room 3 (22 cfu/m
3
). These observations support the concept
that part of the laboratory contamination probably results
from the in situ manipulation of fungal cultures in room 3 and
mostly strains ofAspergillus, which are the main micromy-cetes responsible for human mold infection. An outdoor
origin of the fungus can be excluded, because air system
of ventilation/filtration in this room is high performance and
prevents penetration of outdoor particles in the laboratory
(Fig. 1 ). Moreover, in the case of an outdoor airborne con-tamination, we would have revealed the presence of Cla-dosporium which is largely predominant in outdoor air of
Dijon hospital[21] .