... Manno, , Sensors and Actuators B, vol. 145 , p. 7 94, 2010. [37] P G. Su and T T. Pan, Mater. Chem. and Phys., vol. 125, p. 351, 2011. Monitoring, Control and Effects of Air Pollution 66 ... ppm 40 ppm 30 ppm 20 ppm 10 ppmSensitivity [RHCHO/R air ] Fig. 7. HCHO Gas-sensing properties of LaFeO3 [17]. Monitoring, Control and Effects of Air Pollution 68 Fig. 14. ... Monitoring, Control and Effects of Air Pollution 54 23/%C O ai rRR 382000/ppmC H air RR 50/ppmHCHO air RR LaFeO3 1.03 1.00 1.80 La0.8Sr0.2FeO3 0.89 1.07 14. 7...