Respirators: Research Questions the Safety of Blower-Equipped Carbon Canister
Breathing Devices
Compliance Advisor
January 31, 2007
A new study raises questions about the safety of the growing trend toward
equipping carbon canister protective breathing devices with a blower device to
enable personnel to breathe easier. Marco J. G. Linders and colleagues in The
Netherlands point out that such respiratory protective devices (RPDs)
traditionally are operated by human lungs. The inhale-exhale cycle results in a
pulsating pattern of air flow over the activated carbon filter material. The
carbon material adsorbs toxic gases, preventing inhalation by military, safety,
security and other personnel equipped with RPDs.
Their report, scheduled for the June 6 issue of the American Chemical Society's
Industrial & Engineering Chemistry Research, explains that addition of a blower
creates a power-assisted breathing device with a constant airflow over the
activated carbon. The researchers describe laboratory tests showing that the
constant flow can result in release of high concentrations of contaminants
previously adsorbed to the activated carbon granules.
Release happens faster under humid environmental conditions than under dry
conditions. The experiments also suggested that contaminants might be
redistributed inside the activated carbon canister between uses, leading to
increased release of the contaminants during the next use.