BENGALURU: In all, 48 air quality sensors from six manufacturers were tested at the India Air Quality Sensor Evaluation Facility at CSTEP, Bengaluru. These sensors measured common pollutants such as particulate matter (PM2.5 and PM10), nitrogen dioxide, ozone, and carbon monoxide. The sensors were then placed next to a reference monitor and observed for around a couple of months to check for consistency and accuracy, and for about eight months to check for durability and reliability.
Interestingly, it was found that even when measuring identical concentrations, sensors from different manufacturers produced varying results while measuring the air quality index (AQI) of a given environment. Of particular note was the fact that fluctuations were observed even among sensors from the same manufacturer.
Moreover, no sensor was consistently accurate for all pollutants when compared with the reference system. Particulate matter measurements were more reliable than those for gases such as nitrogen dioxide and ozone, and carbon monoxide readings were more or less consistent.
Some gas sensors showed faulty behaviour like capped readings, and many PM sensors stopped working within six months. The study recommended regular checks of these sensors (every three months), and for more such studies across India for analysing a pool of findings.