1	Engineering Controls for Reducing Indoor Concentrations of Bioaerosols Jennifer Jeffers, University of Notre Dame Professors Shelly L. Miller and Mark Hernandez University of Colorado at Boulder August 6, 2004
2	Introduction Bioaerosols, aerosols containing particles of biological origin, can cause infectious diseases and are of concern in dealing with indoor air pollution and bioterrorism. Air filters have been designed to remove and inactivate particles, including bioaerosols, from indoor air. Ultraviolet germicidal irradiation (UVGI) is one possible method of controlling contamination in rooms and in buildings’ heating, ventilation and air conditioning (HVAC) systems by inactivating the bioaerosols.
3	Engineering Controls Two methods of engineering controls were used: In-room air filtration Ultraviolet germicidal irradiation (UVGI) Three parts of project: Air filters Upper-room UVGI In-duct UVGI
4	Microorganisms Used Parts 1 and 2: Aspergillus versicolor, fungus, size: 5-7µm, spores can be used as subpathogenic surrogates Part 3: Mycobacterium parafortuitum, bacteria, size: 1µm, has a structure and environmental sensitivity similar to the bacteria that causes tuberculoses
5	Protocols
6	Part 1- Air Filters Objective: determine the effectiveness of air filters at removing and inactivating Aspergillus versicolor Two types of air filters were used- Ionic Breeze (commercially available) and Jaguar (prototype) both containing UV-C lamps Ionic Breeze claims to have a clean-air delivery rate (CADR) of 46 m³/h, weighs 4.8 kg and costs $500 Jaguar claims to have a CADR of 425 m³/h, weighs 12 kg and has no associated cost
7	The Air Filters
8	Configuration of Test Chamber for Part 1
9	Part 1 Methods Aspergillus versicolor was aerosolized for 75 minutes and 6 samples were collected at 30 minute intervals for 90 minutes following the aerosolization (2 samples per time period). Each air sample was plated on 3 Petri dishes of malt extract agar and incubated for 7 days at 24ºC The plates were then counted to determine the number of colony forming units (CFU), those that are able to reproduce
10	Experimental Scenarios
11	Part 1 Results
12	Part 2- Upper-room UVGI Objective: to determine the effectiveness of upper-room UVGI on inactivating Aspergillus versicolor 5 UVGI lamps located in the room were used: 4 in each corner and one in the center of the ceiling Corner lamps: 36 W each Center lamp: 72 W
13	Test Chamber and UV lights
14	Test Chamber Configuration for Part 2
15	Part 2 Methods Aspergillus versicolor was aerosolized for 75 minutes and 6 samples were collected at 30 minute intervals for 90 minutes following the aerosolization (2 samples per time period). Each air sample was plated on 3 Petri dishes of malt extract agar and incubated for 7 days at 24ºC The plates were then counted to determine the number of colony forming units (CFU), those that are able to reproduce
16	Part 2 Results
17	Part 3- In-duct UVGI Objective: determine the effectiveness of in-duct UVGI on inactivating Mycobacterium parafortuitum aerosolized from the outdoor air intake of the HVAC system Three sampling locations: outdoor air duct, supply air duct and in the room with 2 BioSamplers in each location Three UV lamps 20 inches in length were placed in the supply air duct 12 inches apart UV intensity- 5 inches from the bottom of the duct: 1.50 µW/cm²(StDev. 0.20) and 19 inches from the bottom of the duct: 1.13 µW/cm² (StDev. 0.11) Distance from UV lamps to supply air duct BioSamplers was 3.8 m
18	Test Chamber Configuration for Part 3
19	Protocols for Part 3 Velocities of the air in the ductwork were calibrated to achieve velocities consistent with typical air flows and isokinetic air sampling. 100% outdoor air was used Isokinetic (“equal-velocity”) Sampling: nozzle tip opening (A_n) and sampling flow rate (Q_m) must be adjusted to obtain a velocity v_n=Q_m/A_n equal to the gas stream velocity (v_s) at the point of sampling Shrouds were made for the BioSamplers using these calculations
20	Ductwork
21	Experimental Scenarios
22	Part 3 Methods Mycobacterium parafortuitum was aerosolized from the outdoor air intake for 90 minutes and the air samples were collected at the 3 locations during the last 30 minutes of aerosolization The samples were plated on trypic soy agar Petri dishes and incubated for 2-3 days at 38°C The plates were then counted to determine the CFU concentration Microscope slides made with DAPI stain were used to determine the total number of bacteria (live and dead)
23	Part 3 Results- 440 ft/min
24	Part 3 Results- 1000 ft/min
25	Conclusions Part 1: The Jaguar prototype was more effective at inactivating A. versicolor than the Ionic Breeze, even though in a 89 m³ room, neither air filter was as effective as the manufacturer claimed Part 2: Upper-room UVGI can inactivate A. versicolor in a 89 m³ room, but not at the same rate as bacteria Part 3: In-duct UVGI is effective at inactivating M. parafortuitum at low air velocities, while it is not effective at high air velocities.
26	Acknowledgements Elmira Kujundzic for helping design and run the in-room and in-duct experiments and with all the data analysis Fatimah Matalkah for teaching me all the necessary lab techniques and letting me participate in her air filter study Cody Howard for helping run all the experiments in the test chamber Professors Shelly Miller and Mark Hernandez for the opportunity to work on this project
27	Questions?