Respiratory protection for physiologically straining environments

Abstract

People who work in hazardous environments under high physiological stress often have to weigh up the benefits and difficulties of wearing respiratory protection. By developing filter materials that provide comparable smoke particle protection at a significantly lower breathing resistance, exposure to physiological stress may be reduced without jeopardizing protection. In this paper, we investigate to this end the use of stationary electrostatic surface charges, which are known to dramatically improve the efficiency of filter media to fine particles at next to no change in breathing resistance. Filtration test results presented show that some high temperature polymer fiber materials commonly used for personal protective equipment can in fact reach best practice filtration performance if combined with a suitable fiber counterpart. Tribo-electric fiber blends made from combinations of polypropylene with poly-imide-amide, poly(m-phenylene benzimidazole), meta-polyaramid or para-polyaramid have been found to generate significant electrostatic enhancements in nonwoven needle felts that are stable over time. Results suggest that polypropylene is an essential component of fiber blends that reach best practice electrostatic performance with the exception of a meta-aramid fiber blended with wool that appears to work as well. As a result, it is possible to manufacture heat resistant garments for respiratory protection against smoke particles, which could be similar to a bandana and provides protection at a reduced breathing resistance.