1. Wireless indoor air quality (IAQ)
monitoring in classrooms and
laboratories (VOC's, CO, CO2, and T)
1
PID Analyzers, LLC

2. Introduction
2
 High levels of CO2 (>1,000 ppm) can result in students
feeling drowsy or sick
 Poor air quality in school classrooms is a serious problem
now a “typical 700-square-foot classroom with 20 to 30
occupants ventilated by a standard HVAC system”. (Aiken,
Tom, Cleanfax Online: http://www.cleanfax.com/disaster-restoration/article/maintaining-healthy-
classrooms-with-air-quality-monitors)
 We initially used a Model 114 IR Analyzer but we also
designed a low cost single channel IR logger for CO2 to
monitor labs, offices & class rooms
 A positive benefit to improving IAQ in classrooms is that
a number of studies have shown that improved air
quality can lead to higher test scores. (Aiken, Tom, Cleanfax Online:
http://www.cleanfax.com/disaster-restoration/article/maintaining-healthy-classrooms-with-
air-quality-monitors)
PID Analyzers, LLC

3. ASHRAE’S POSITION ON CARBON DIOXIDE (CO2)
LEVELS
3
 American Society of Heating, Refrigeration and Air
Conditioning Engineers (ASHRAE) has a guideline of 1,000
ppm CO2 for indoor spaces
 CO2 has been used as a basis for ventilation
 CO2 levels are good predictors or surrogates for human
emitted bioeffluents (i.e., odors)
 If the ventilation rate is set so that 1000 ppm CO2 is not
exceeded and if CO2 is controlled by any method other than
dilution, the effects of possible elevation of other
contaminants must be considered.”
 CO2 levels should be measured during the time of occupancy
which is defined for the classroom as the time between initial
occupancy in the morning and dismissal time for the students.
PID Analyzers, LLC

4. CO2 Levels & Health Effects
4
 325 - 350 ppm – background (normal) outdoor air level
 750- 1,000 ppm - typical level found in occupied spaces
with reasonable air exchange.
 1,000 – 2,000 ppm - level associated with complaints of
drowsiness and poor air.
 2,000 – 5,000 ppm – level associated with headaches,
sleepiness, and stagnant, stale, stuffy air. Poor
concentration, loss of attention, increased heart rate and
slight nausea may also be present.
 >5,000 ppm – Exposure may lead to serious oxygen
deprivation resulting in permanent brain damage, coma
and even death.
PID Analyzers, LLC

5. IR Sensor & VOC sensor Schematic
5
IR Sensor Schematic-CO2 PID Schematic-VOC’s
PID Analyzers, LLC

6. IR Spectrum for CO2
6
Dual Beam IR Meas. &
IR spectrum of CO2 Ref. Wavelengths
PID Analyzers, LLC

7. Laboratory 200 sq ft/person
450
416
416 7
400
370.5369.2369.2369.2369.2369.2367.9367.9367.9367.9
369.2369.2369.2369.2367.9367.9367.9367.9367.9
369.2369.2369.2369.2367.9367.9367.9367.9367.9
369.2369.2369.2369.2367.9367.9 367.9367.9 367.9367.9
367.9
367.9
367.9
350
ppb VOC (Red) / ppm CO2 (Yellow)
327.6
326.3
325
314.6 314.6314.6
314.6
314.6
314.6
300
250
Series1
200 Series2
VOC's and CO2 Variation in Laboratory 2 per. Mov. Avg. (Series1)
2 per. Mov. Avg. (Series2)
150
100
50
21 27
15 19 17 20 13 13
127 118126 7156 7 8 11814911999159916 18
4 2 334 39 6 4 10 10 5 7 39 108
0
-6 -11
-8
2/1/2011 9:00
2/1/2011 9:07
2/1/2011 9:14
2/1/2011 2/1/2011 9:28
9:21 2/1/2011 9:36
2/1/2011 9:43
2/1/2011 9:50
2/1/20112/1/2011 10:04
9:57
-50
PID Analyzers, LLC

8. CO2 in Office (75 sq ft/person)
8
PID Analyzers, LLC

9. Components of
Single Channel Logger
9
Enclosure
Battery
45 hours for CO2
150 Hours for EC
rechargeable
PID Analyzers, LLC

10. CO2 in Classroom
10
Model 114 IR CO2 Photo of Classroom
PID Analyzers, LLC

11. CO2 Measurements
11
CO2 Variation in Different Locations Location & Description
 1 lab 4 people
15 Variation of CO2  2 office 3 people
14
 3 home 2 people
13
12  4 classroom 15 students 4 teachers
11  5 outside air near office
10  6 class room 20 students 2 teachers
9
Room #
 7 outside air on cc
8
7
 8 Hotel room
6  9 Hotel corridor
5  10 classroom 25 people
4  11 classroom larger 40 people
3
 12 classroom 10 people
2
1  13 classroom 3 people
 14 classroom no people
0 500 1000 1500
 15 classroom 13 people
ppm CO2
PID Analyzers, LLC

12. Conclusions
12
 CO2 is a good indicator of room air quality and
problems can be found quickly and efficiently
 Initial measurements were made with a CO2 Model
114 IR but a single channel CO2 dosimeter has been
designed and will be available in the Fall 2012
 Many rooms were found to be close to 1,000 ppm in
homes, offices and classrooms in the winter. With
adequate ventilation, warmer temperatures, average
classrooms could be 750 ppm or lower
 The Bluetooth slave module is capable of sending
data 100-200’ to a master module in a PC
PID Analyzers, LLC