Questioning the safety of blower-equipped carbon canister breathing devices
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 ACS' Industrial & Engineering Chemistry Research, a bi-weekly journal, 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.