Table 1.

Low-cost sensors discussed in this paper.

Pollutant	Sensor	Cost ($)	Dimensions (mm)	Technology	Specifications
PM	Shinyei PPD42NS	10	59 (W) × 45 (H) × 22 (D)	volume light scattering (digital output)	> 1 μm
PM	Shinyei PPD20V	150	88 (W) × 60 (H) × 20 (D)	volume light scatterin (analog output)	> 1 μm
PM	Shinyei PPD60PV	150	88 (W) × 60 (H) × 20 (D)	volume light scattering (analog output)	> 0.5 μm
Temperature and RH	Sensirion SHT 15	40	5 × 7.5 × 2.6 (D)	band-gap displacement capacitance	–40 to 100 ± < 0.5°C 0 to 100% ± 2%