Bengaluru study evaluates performance of low-cost particulate matter sensors

“From the study, it is evident that PM 2.5, temperature, and relative humidity measurements of LCSs can capture trends. The uncorrected measurements can be used for qualitative information. For example, LCS can be used to identify specific days or locations that are more polluted than others. Given the affordability, portability, and ease of installation, LCSs can help give air quality information in areas with no monitoring. The high temporal resolution (compared to reference-grade instruments) is also useful in capturing short pollution events,” CSTEP said.

During the assessment, various LCSs measurements were compared with the measurements of a reference-grade instrument. A beta attenuation monitor was used as a reference-grade instrument. Beta attenuation monitoring is widely used as a traditional air monitoring technique.

“Most of the LCSs quantify PM2.5 based on the light scattering technique, which is sensitive to environmental factors such as humidity in the atmosphere and the optical and microphysical properties of particulate matter (PM) in addition to the particle concentration. This can introduce bias in LCSs measurements of PM, thereby requiring evaluation before publishing,” CSTEP said.

LCSs are becoming popular for monitoring air pollution because of their low cost and portability. They could also aid in monitoring air pollution in areas/geographies where access to reference-grade monitors is limited. The low cost and portability of LCSs, however, come with some trade-offs on data quality, reliability and shelf life. South Asian countries could especially benefit from using LCSs because reference-grade monitors are expensive and not always affordable, according to CSTEP.

Dr Sreekanth Vakacherla, project lead of CSTEP, said, “Low-cost sensor technology for air pollution measurements and its calibration techniques are continuously evolving. More accurate measurements and longer shelf life could be expected from these sensors down the line.”