Field Evaluation
TSI Air Assure PM2.5 Sensor

Background• From 12/18/2015 to 02/15/2016, three TSI AirAssure PM2.5 Sensors were deployed inRubidoux and ran side-by-side with two Federal Equivalent Method (FEM) instruments
measuring the same pollutant• AirAssure Sensor (3 units tested): Particle sensors (optical; non-FEM)’
 Each unit measures PM2.5 Mass (μg/m3)
 Unit cost (complete box with sensor, datacomm board, and ventilation): ~$1,500
 Time resolution: 5-min Units IDs: 004, 005, and 010• MetOne BAM (reference method):
Beta-attenuation monitor (FEM)
Measures PM2.5 mass (μg/m3)
Unit cost: ~$20,000
Time resolution: 1-hr

• GRIMM (reference method):Optical particle counter (FEM)
Uses proprietary algorithms tocalculate total PM, PM2.5, and PM1mass concentration (μg/m3) fromparticle number measurements
Unit Cost: ~$25,000 and up
Time resolution: 1-min2

Data validation & recovery• Basic QA/QC procedures were used to validate the collected data (i.e. obvious outliers,negative values and invalid data-points were eliminated from the data-set)• Data recovery for PM2.5 from all three AirAssure Sensors was > 99%

AirAssure sensors: Intra-model variability• Low measurement variations were observed between the three AirAssure devices tested

3Data validation & recovery• Basic QA/QC procedures were used to validate the collected FEM data (i.e. obviousoutliers, negative values and invalid data-points were eliminated from data-set)• PM2.5 data recovery was 96% for the GRIMM and 99% for the BAM

Equivalent methods: BAM vs GRIMM• Very good correlation between the two equivalent methods

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AirAssure Sensor vs FEM GRIMM (PM2.5 Mass; 5-min mean)• AirAssure PM2.5 mass concentration
measurements correlate very well withthe corresponding FEM GRIMM data
(R2 > 0.81)• The AirAssure devices are highly
accurate relative to the FEM methods
used; however, their readings areslightly overestimated5

AirAssure Sensor vs FEM GRIMM (PM2.5 Mass; 1-hr mean)• AirAssure PM2.5 mass concentration
measurements correlate very well withthe corresponding FEM GRIMM data
(R2 > 0.83)• The AirAssure devices are highly
accurate relative to the FEM methods
used; however, their readings areslightly overestimated

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AirAssure Sensor vs FEM GRIMM (PM2.5 Mass; 24-hr mean)• AirAssure PM2.5 mass concentration
measurements correlate very well withthe corresponding FEM GRIMM data(R2 > 0.86)• The AirAssure devices are highly
accurate relative to the FEM methods
used; however, their readings areslightly overestimated7

AirAssure Sensor vs FEM BAM (PM2.5 Mass; 1-hr mean)• AirAssure PM2.5 mass concentration
measurements correlate very well withthe corresponding FEM GRIMM data
(R2 > 0.76)• The AirAssure devices are highly
accurate relative to the FEM methods
used; however, their readings areslightly overestimated8

AirAssure Sensor vs FEM BAM (PM2.5; 24-hr mean)• AirAssure PM2.5 mass concentration
measurements correlate very well withthe corresponding FEM GRIMM data
(R2 > 0.87)• The AirAssure devices are highly
accurate relative to the FEM methods
used; however, their readings areslightly overestimated9Discussion• Overall, the three AirAssure sensors were reliable (i.e. no down time over a period of
about two months; data recovery close to 100%) and characterized by low intra-model
measurement variability• Data collected using these devices was very well correlated with that obtained using
substantially more expensive FEM instruments (i.e. BAM and GRIMM)• PM2.5 sensor measurements were accurate but slightly overestimated. However, nosensor calibration was performed by SCAQMD staff prior to the beginning of the fieldtesting• Laboratory chamber testing is necessary to fully evaluate the performance of thesesensors over different / more extreme environmental conditions• All results are still preliminary

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