TESTING & VALIDATION OF MOBILE AIR QUALITY MONITOR FOR SENSING & DILINEATING VOC EMISSIONS

Abstract

Volatile Organic Compounds (VOC) are chemical compounds having high vapor pressure, and thus are volatile in nature at room temperature. There is a limit of VOC content in the air beyond which they can cause respiratory disorders, nausea, loss of coordination, and in some cases may lead to lung or kidney damage and many other health hazards. Due to the increase in industrialization and urbanization, there have been VOC emissions into the air at greater scales. This has prompted monitoring of VOC emissions through innovative sensing technologies, which give continuous information of the VOC pollutants in the air. A Metal Oxide Sensor (MOX) is one of the sensors widely used for monitoring VOCs in the air. It consists of a porous layer heated by a filament that undergoes a redox reaction when it comes in contact with a VOC, changing the electrical resistance across the circuit in proportion to the concentration of the VOC. This transduction principle gives high sensitivity for monitoring air quality, and therefore can be used in continuous monitoring of industrial emissions. An important characteristic while considering this sensor for monitoring air quality is its selectivity, that is, its ability to discriminate between two compounds.
A uRADMonitor A3 mobile air quality monitor, containing a MOX sensor (Bosch BME680), was tested and validated in this research for its ability to monitor VOC concentration and for determining the air quality index. Initially, point source emissions of a gasoline generator (Hyundai 1750W) were measured by the URADMonitor A3 and compared with a Horiba MEXA-584L device for validating the measurements. Subsequently, two URADMonitor A3 monitors were tested (in identical positions one at a time, and then in different positions simultaneously) for studying its sensitivity, accuracy, and precision. The electrical resistance values were noted, brought to a common baseline based on each sensor’s historical data, and scaled to a normalized internal. Linear and non-linear scaling approaches were compared. This normalized scaling approach allowed comparison of two units using the same VOC sensor, but is intended to also work also between different types of VOC sensors (e.g. BME680 vs MP503). The goal is to develop an improved method for determination of air quality index at a wide range of concentrations and for a wide range of VOCs.

Full text

TESTING & VALIDATION OF MOBILE AIR QUALITY
MONITOR FOR SENSING & DILINEATING VOC
EMISSIONS
A&WMA’s 112th Annual Conference & Exhibition
Québec City, Québec
June 25-28, 2019
Abstract ID: 599728
Presenting Author: Govind Singh N. Thakor, Graduate Student at University of Guelph
Co-Author: Piaoyu Hu, Graduate Student at University of Guelph
Co-Author: Radu Motisan, Founder of Magnasci SRL
Primary Author: Emily Chiang, Associate Professor at University of Guelph
Primary Author: Rafael Santos, Assistant Professor at University of Guelph

Volatile Organic Compounds Pollutant Health
Hazards
Respiratory Disorders
Nausea
Loss of Coordination
Lung Damage
Kidney Damage
2

Outdoor Sources of VOC Pollutants
Industrial Processes
Road Transport
Vegetation
Solvent Use
3

Indoor Sources of VOC Pollutants
Chemical substances from furniture
Paint
Cleaning products
Wood
Copy and printing machines
Varnishes
Tobacco products
4

Need For Monitoring
Continuous measurement
Real time data
Should be cheap
Easy to handle
Short time analysis
Better correlation of data
5

Characteristics of VOCs
Organic aromatic compounds of
carbon
Low boiling point (below 200 oC)
Gets evaporated in air very easily
at room temperature
6

Threshold Limits of Some VOC
Pollutants
Sr.no.
Pollutant Source Threshold Limit
(ppm)
1 Ethanol Glass Cleaners, Dish Washers,
Detergents & Laundry Detergents 1000
2
Formaldehyde
Molded Plastics, Finished Plastics
and Wooden Products 0.1 to 0.3
3 Acetone Polish, Furniture Polish, Nail
Polishes, Wallpapers 750 to 1000
4 Benzene
Furniture made with Paint or Glue
0.1
5Dichloro
Benzene Mothballs & Deodorant 25 to 50
7

Sensor Characteristics to
Measure VOCs
SENSITIVITY SELECTIVITY
8

9

uRAD Monitor A3
Worldwide network of automated monitors
It has sensors for :
•Particulate Matter
•Ozone
•Formaldehyde
•CO2
•VOCs
•Temperature
•Barometric Pressure
•Air Humidity
10

Practical Challenges of Sensing VOCs
Humidity decreases sensitivity of metal
oxide sensor
Quantification of different
concentrations of VOCs
Non Linear output with respect to
input
11

Research Focus
Di-linearization of Output for realistic
representation of Air Quality Index
Find out ways of getting distinctive
output of sensor for every
concentration of VOC
12

Methods
Temperature Modulation
Hyphenation
Pattern Recognition Systems
Changing Material of Film
Using Nanomaterial sensing elements
13

Validation of Measurements of VOC From a
Generator by A3 Monitor
14

Measurement of VOC from Different Positions
•Generator against the
Wall
Generator at the centre
Of the roof
15

Monitoring of Lab
16

Conclusion
•This Method can be useful to determine Air Quality Index.
•Many other VOCs can be monitored if the sensor is able to
discriminate and quantify different concentrations.
17

REFERENCES
•Andrzej Szczurek, Monika Maciejewska (2012) Assessment of VOCs
in air using sensor array under various exposure conditions.
•Chengxiang Wang, Longwei Yin *, Luyuan Zhang, Dong Xiang and
Rui Gao (2010) Metal Oxide Gas Sensors: Sensitivity and Influencing
Factors
•Amir Hossein Alinoori and Saeed Masoum (2018) Multicapillary Gas
Chromatography Temperature Modulated Metal Oxide
Semiconductor Sensors Array Detector for Monitoring of Volatile
Organic Compounds in Closed Atmosphere Using Gaussian
Apodization Factor Analysis
•N. Masson∗, R. Piedrahita, M. Approach (2014) Approach for for
quantification of metal oxide type semiconductor gassensors used
for ambient air quality monitoring 18

THANK YOU
GOVIND SINGH THAKOR
Email: gthakor@uoguelph.ca
govind.thakor@gmail.com
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