Post on 23-Feb-2016
description
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 rates Low: 5 – 6 ACHHigh:
10 – 12 ACH Density of Room in cages/sq.ft. (# of cages in room)
PeriodRats (140)
1.2(280)
1.2(540)
0.8(175)
0.6(190)
0.6170)
0.2(65)
0.1(25)
1 High Low Low High High Low Low High
2 Low High High Low Low High High Low
3 High Low Low High High Low Low High
4 Low High High Low Low High High Low
Air Flow
Room Volume 2800 cu.ft.
Room Pressure Differential Positive
Cage Pressure Differential Positive
Room Ventilation Rate High Low
CFM Supply 500 250
ACH 10.7 5.3
CFM from Racks (2) 100 100
CFM for Pressure Offset 100 100
CFM from Room Exhaust 300 50
Ventilation Cost ($3.50/cfm) $1750/year $875/year
Study Design
Compare Low vs. High room ventilation rates for:• Room CO2 (difference between supply - exhaust air)• Room Dew Point Temperature (difference between
supply - exhaust air)• Room Mouse Allergen (Mus m1)• Room Endotoxin• Intracage Ammonia, CO2, 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, CO2, 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
*
Rats 1.2 1.2 0.8 0.6 0.6 0.2 0.10
20
40
60
80
100
120
140
Room CO2 Level - Difference between Supply Air
High
Low
Density of Room (cages/sq.ft.)
CO2
(ppm
)
Rats 1.2 1.2 0.8 0.6 0.6 0.2 0.10.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Room Dew Point Temperature - Difference between Supply Air
HiLo
Density of Room (cages/sq.ft.)
°F
0.6 1.20
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Room Level of Mus M 1 Allergen
High
Low
Density of Room (cages/sq.ft.)
ng/m
3
0.6 1.2
-0.005
5.20417042793042E-18
0.005
0.01
0.015
0.02
0.025
0.03Room Level of Endotoxin
High
Low
Density of Room (cages/sq.ft.)
ng/m
3
A B C D800
900
1000
1100
1200
1300
1400
CO2 Level within Cages
Hi
Lo
Cage
ppm
A B C D0
5
10
15
20
25
30
35
Ammonia Level Within Cage at 2 Weeks
Hi Lo
Cage
ppm
A B C D0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Temperature Difference Between Cage & Room
Hi
Lo
Cage
°F
Period 1 Period 2 Period 3 Period 430%
40%
50%
60%
70%
% Humidity within Cage
Hi
Lo
-5 10 25 40 55 70 850
1
2
3
4
5
6
7
8
9
Room EtOH Level After a Spill
HighLow
Minutes After Spill
ppm
*
-5 10 25 40 55 70 850
1
2
3
4
5
6
7
8
9
EtOH Level After a Spill with Demand-Controlled Vential-tion (DCV)
High - without DCV
Low - without DCV
Low - with DCVpp
m
Minutes after spill
Summary of Results
• Low ventilation rate:• Slightly increased level of CO2
• 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 CO2 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