Shenyei PPD42NS Gets an Accuracy Test
The Shenyei PPD42NS is a $15USD optical sensor that uses an LED and a lens to determine the concentration of dust in a partially closed chamber that draws in air from its surroundings. A group of academics interested in the applications of low-cost sensors for valid scientific air quality monitoring wanted to know how does this low-cost newly off-the-shelf PM monitor compare with costlier models used by governments (BAM-1020, Met One Instruments) researchers (GRIMM OPC, Model 1.108), and companies (DC1700, Dylos Corp).
This is what they found:
”Performance at 1 [hour] integration times was comparable to commercially available optical instruments costing considerably more.” Or to put it more plainly, the results of the low-cost sensor were about equivalent to more expensive ones when analyzing data at hourly intervals."
A full description of their methodology can be found here: Field_Calibrations_of_a_low-cost_aerosol_sensor_at_a_regulatory_monitoring_site_in_California-2014.pdf
Questions and next steps
In situations where a lower number of high-cost sensors are used to model exposure over large areas (as is often the case in cities where environmental monitoring infrastructure is scarce), how will new monitoring data generated from low-cost and accessible instrumentation be incorporated into regulatory decision making. This study suggests that the gap in data quality is shrinking and that deploying low-cost sensors as a complement to high-cost monitors has real potential. But that decision making part, that is still an important open question.
Why I'm interested
I work with the Earth Journalism Network, global community of environmental journalists interested in exploring how citizen science can improve the quality of our reporting.