Greetings,
l winter a few colonies inside each year, between 80 and 120, mostly nucs as
my production colonies winter outside and do so very well even though the
temperature may descend to 40o below. My indoor facility is my hot room and
is equipped with a recirculating fan (blower) and conduit to ensure that the
air is well mixed. It also has an extracting fan and heater, both controlled
by thermostats. The temperature is kept at plus 3oC , more or less. Most
beekeepers here in Quebec enter the building 3 to 5 times during the winter
to check the mechanical systems and to remove the dead bees. There are
normally quite a few inches of dead bees on the floor. When l first started
using an indoor facility, l did the same as the others and removed the dead
bees a few times during the winter. I found that after the work l would have
coughing spells for a day or so after. I subsequently used a dust mask when
cleaning out the dead bees.  Since a few years, l no longer remove the dead
bees during the winter.  I remove the hives in the spring and push the dead
bees towards the end of the building as l remove each row of hives, so as
not to walk all over the dead bees. Since l have been rob feeding in the
autumn l find that l have a lot less dead bees in the wintering building, l
presume that they die whilst collecting the syrup from the barrels. NOT in
the barrels.
I know that this is a long answer to a simple question, but l wished to
explain how l manage the colonies and the building. I know of no research
that has been done regarding indoor wintering health hazards but the
presence of millions of dead dry bees being crushed underfoot cannot be
good. I also know of a beekeeper that felt he was exposed to high CO2 levels
while working inside the building.
Peter John Keating .            Quebec (still in Canada)

> Having heard comments in conversation but no depth to the subject - I
wonder if those concerned with the practice of over
> wintering bees in cellars or controlled/ enclosed buildings could comment
on the health risks posed to people entering these
> buildings.
> Apparently the dead bees/ dust due to the build up from "bee bits" is
hazardous!