Effect of Room Ventilation Rates in Rodent Rooms with Direct-Exhaust IVC Systems Roger Geertsema DVM, DACLAM, DAVCPM

Background Vivarium with Individual Ventilated Cages (IVC) for rodents with cage exhaust directly ventilated out of room Tecniplast IVC with positive pressure cages (70% cage exhaust rate)

Specific Aims Can room ventilation rates be safely lowered in rodent rooms utilizing direct exhaust individually-ventilated caging (IVC) Air quality within the room that could have an occupational health or animal wellbeing effect Changes in intracage environmental conditions that could impact animal wellbeing or complicate research results

Study Design 8 rodent rooms 7 mouse rooms 1 rat room 2 ventilation ratesLow: 5 – 6 ACH High: 10 – 12 ACH Density of Room in cages/sq.ft. (# of cages in room) Period Rats (140) 1.2 (280) 1.2 (540) 0.8 (175) 0.6 (190) ) 0.2 (65) 0.1 (25) 1HighLow High Low High 2LowHigh Low High Low 3HighLow High Low High 4LowHigh Low High Low

Air Flow Room Volume2800 cu.ft. Room Pressure DifferentialPositive Cage Pressure DifferentialPositive Room Ventilation RateHighLow CFM Supply ACH CFM from Racks (2)100 CFM for Pressure Offset100 CFM from Room Exhaust30050 Ventilation Cost ($3.50/cfm) $1750/year$875/year

Study Design Compare Low vs. High room ventilation rates for: Room CO 2 (difference between supply - exhaust air) Room Dew Point Temperature (difference between supply - exhaust air) Room Mouse Allergen (Mus m1) Room Endotoxin Intracage Ammonia, CO 2, Temperature, and Humidity Create a controlled spill of EtOH in room Evaluate the peak level and amount of time to return to baseline at Low vs. High ventilation

Demand-Controlled Ventilation (DCV) Computer controlled Phoenix valves in supply and room exhaust Monitoring of room air quality for temperature, dew point temperature, CO 2, dust particles, and Total Volatile Organic Chemicals (TVOC) Sample taken every 15 min. from room exhaust, not the cage exhaust Ability to increase ventilation rate based on monitoring parameters

*

*

Summary of Results Low ventilation rate: Slightly increased level of CO 2 Slightly increased Dew Point Temperature Increased time to clear a VOC spill (demand-controlled ventilation will mitigate this) No difference in: Mus m1 Endotoxin Intracage ammonia, CO2, temperature, and humidity

Conclusions It is safe to lower the room ventilation rate to 5 – 6 ACH both for human workers and animals with a direct exhaust IVC system that is properly designed and maintained - This may not apply to all IVC systems Although some statistically significant effects were observed, air quality still well within acceptable guidelines (ASHRAE limit for CO 2 in room air is 1000 ppm) With a demand-controlled ventilation system, the air is cleared of a spilled VOC faster (assuming the VOC is able to be detected by the system)

Acknowledgements ACLAM Foundation Grant Dr. Lindsell, Matthew Gudorf, Alvin Samala, Scott Smith, & Michael Phelan