Control of Bioaerosols Concentrations in Air Concentrations of

Control of Bioaerosols

Concentrations in Air • Concentrations of indoor bacteria range from <100 -1500 cfu/m 3; avg 0 -500 – heated dwellings lower • Avg concentrations of outdoor bacteria 200 -1000 • Avg concentrations of indoor Fungi range from 10 -500 • Avg concentrations of Outdoor Fungi range from 100 -1000

Air Filtration • Part of most HVAC systems • Hospitals have very intricate systems • No universal standard method for evaluating filter performance – Thus advertised efficiencies may be misleading • Most difficult range of particles to filter 0. 2 to 0. 3 micron; generally particles categorized as > 0. 5 or < 0. 5 microns • Peak Particle Removal with 12 -15 ACH

Types of Filters • Fiberglass- typical household filter 5 -7% effective • Electronic- lose filtering 50% capacity in first week • HEPA- High Efficiency Particulate Air, 99. 97% of pollutants at 0. 3 microns • ULPA- Ultra Low Penetration Air, 99. 9997% of particles as 0. 1 micron • Electrostatic- “static charged”, 95%

Other Air Treatments • Ionizer- negative ion generation • Ozone- good disinfectant, safety risk • UV- good disinfectant, 253. 7 nm, long exposure times?

Cundith et al. , Meat Processing Plant • Deployed EP filters with scanning UV • Three Rooms (100% recirculation) – Processing- 10ºC, 110 m 3, 3 m/min – Chill Cooler- 0 -2ºC, 130 m 3, 21 m/min – Aging Cooler- 0 -2ºC, 360 m 3, 8 m/min

Kujundzic E, et al. . • Effects of ceiling-mounted HEPA-UV air filters on airborne bacteria concentrations in an indoor therapy pool building. J Air Waste Manag Assoc. 2005 Feb; 55(2): 210 -8. – The purpose of this study was to assess the effectiveness of a new generation of high-volume, ceiling-mounted high-efficiency particulate air (HEPA)-ultraviolet (UV) air filters (HUVAFs) for their ability to remove or inactivate bacterial aerosol. In an environmentally controlled full-scale laboratory chamber (87 m 3), and an indoor therapy pool building, the mitigation ability of air filters was assessed by comparing concentrations of total bacteria, culturable bacteria, and airborne endotoxin with and without the air filters operating under otherwise similar conditions. Controlled chamber tests with pure cultures of aerosolized Mycobacterium parafortuitum cells showed that the HUVAF unit tested provided an equivalent air-exchange rate of 11 hr(-1). Using this equivalent air-exchange rate as a design basis, three HUVAFs were installed in an indoor therapy pool building for bioaerosol mitigation, and their effectiveness was studied over a 2 year period. The HUVAFs reduced concentrations of culturable bacteria by 69 and 80% during monitoring periods executed in respective years. The HUVAFs reduced concentrations of total bacteria by 12 and 76% during the same monitoring period, respectively. Airborne endotoxin concentrations were not affected by the HUVAF operation.

Cundith et al. Console filtration

Laboratory Control • BSCs • Centrifuge containment • HVAC

Class I • Personnel and Environmental Protection • No Product Protection • Similar to fume hood with HEPA exhaust • 75 LPM • Hard-ducted to BLDG exhaust • 0. 5 inches water

Class I • Some have integral blower • Must be turned off in case of BLDG exhaust failure • Good design to surround all positive pressure plenums with vacuum

Class IIA/B 3 (Now Class II A 2) • 30/70 exhaust/recirculation • HEPA filtered on exhaust and recirculation • 75 LPM • Hard-ducting not recommended • Not rated for volatiles or toxics

Class IIB 1 • Originated with NCI designed cabinet • 70/30 exhaust/recirculation • HEPA filtered on exhaust, recirculation and inflow • Personnel, environment and product protection • 100 LPM • 70% downflow through rear grill; 30% front grill • Hard-ducted; preferably dedicated

Class IIB 2 • Total exhaust • Personnel, environment and product protection • HEPA filtered on inflow and exhaust • 100 LPM • Hard-ducted; 1. 5 inches water; must be interlocked; ideally dedicated • With internal blower may not be hard-ducted

Class III • • Designed for work with BSL 4 agents Interchange box Heavy duty rubber gloves HEPA filtered on supply and exhaust (double or incinerator) • Hard-ducted; dedicated exhaust 0. 5 inches water

BAG-IN BAG-OUT (BIBO) • Additional layer of protection • Between BSC and BLDG exhaust • HEPA • Required for BSL 3/BSL 4 laboratories