Laboratory Evaluation of the Shinyei PPD42NS Low-Cost Particulate Matter Sensor

SENSOR : SHINYEI - PPD42NS R² -values (limited to concentration <50µg/m³) reasonable ok. when the results of all the experiments are pooled, the response of the instruments is highly associated with the diameter of the challenge particle (R2 = 0.80). The Bland-Altman plots demonstrated that when the sensors are corrected for their idiomatic response, the results agree with the APS count data within 10% for concentrations below 150 μg/m3 . This suggests that the accuracy of the Shinyei, when the idiomatic sensor response is accounted for, is acceptable for deployment conditions.

Objective: Finely resolved PM2.5 exposure measurements at the level of individual participants or
over a targeted geographic area can be challenging due to the cost, size and weight of the
monitoring equipment. We propose re-purposing the low-cost, portable and lightweight Shinyei PPD42NS particle counter as a particle counting device. Previous field deployment of
this sensor suggests that it captures trends in ambient PM2.5 concentrations, but important
characteristics of the sensor response have yet to be determined. Laboratory testing was
undertaken in order to characterize performance.

Methods:  The Shinyei sensors, in-line with a TSI Aerosol Particle Sizer (APS) model 3321, tracked particle decay within an aerosol exposure chamber. Test atmospheres were composed of monodisperse polystyrene spheres with diameters of 0.75, 1, 2 3 and 6 um as well as a polydisperse atmosphere of ASHRAE test dust 

Results: Two-minute block averages of the sensor response provide a measurement with low random error, within sensor, for particles in the 0.75–6μm range with a limit of detection of 1 μg/m3. The response slope of the sensors is idiomatic, and each sensor requires a unique response curve. A linear model captures the sensor response for concentrations below 50 μg/m3 and for concentrations above 50 μg/m3 a non-linear function captures the response and saturates at 800 μg/m3. The Limit of Detection (LOD) is 1 μg/m3. The response time is on the order of minutes, making it appropriate for tracking short-term changes in concentration.

Conclusions: When paired with prior evaluation, these sensors are appropriate for use as ambient particle counters for low and medium concentrations of respirable particles (< 100 ug/m3). Multiple sensors deployed over a spatial grid would provide valuable spatio-temporal variability in PM2.5 and could be used to validate exposure models. When paired with GPS tracking, these devices have the potential to provide time and space resolved exposure measurements for a large number of participants, thus increasing the power of a study.