Calcium chloride is a desiccant (moisture absorbent) and will, to a degree, control odors due high humidity.
Calcium chloride, CaCl2, is a common salt and the compound of calcium
and chlorine. It behaves as a typical ionic halide, and is solid at
room temperature. It has several common applications such as brine for
refrigeration plants, for use in concrete, as well as for ice and dust
control on roads. The anhydrous salt is also widely used as a
desiccant, where it will adsorb so much water that it will eventually
dissolve in its own crystal lattice water. It can be produced directly
from limestone, but large amounts are also produced as a by-product of
the Solvay process. Because of its hygroscopic nature, the anhydrous
form must be kept in tightly-sealed containers.
Calcium chloride aggressively absorbs moisture from the air, first
causing a swelling of the crystals. If the air is humid enough and the
temperature is high enough, the crystals melt and liquid saline
solution brine is formed.
Calcium chloride desiccants work well over a temperature range from
freezing up to 80°C or more. At low temperature the salt does not
absorb moisture under dry conditions. In practical terms calcium
chloride desiccants are effective at relative humidity above 30%,
while being more effective under moist conditions.