Air Filtration and the Use of HEPA Filters in Biological Safety Cabinets
Air filtration is a topic affecting everyone’s lives, whether it is for occupational safety requirements, environ mental or home health concerns. Control of airborne particulates in indoor environments is critical to develop quality products, protect employees from contact with hazardous materials, or prevent health problems from prolonged exposure to allergens. How airborne particulates are controlled varies from industry to industry and from an occupational setting to a home environment. To better understand why HEPA filters are used in the biological safety cabinet industry, it is necessary to explore particle sizes, types of filters available for home and occupational use, efficiency and penetration, filter standards and performance testing.
Particles and Relative Micron Size
Particles are generated or become airborne with everyday human activity. Because many people spend the majority of their time indoors at work or home, the quantity of particles floating in the air are of great concern. For example, a sedentary person in a standing or sitting position generates approximately 100,000 particles per cubic foot. Moving from a sitting to a standing position generates 2.5 million particles per cubic foot. Moderate activity generates 30 million particles per cubic foot. Industrial processes in manufacturing or machine shops generate billions of particles per cubic foot.