... year. Monitoring, Control and Effects of Air Pollution 54 23/%C O ai rRR 38 2000/ppmC H air RR 50/ppmHCHO air RR LaFeO3 1.03 1.00 1 .80 La0 .8 Sr0.2FeO3 0 .89 1.07 14.7 ... [RHCHO/R air ] Fig. 7. HCHO Gas-sensing properties of LaFeO3 [17]. Monitoring, Control and Effects of Air Pollution 68 Fig. 14. Time-series plots of CO2 measurements (in the units of ... Monitoring, Control and Effects of Air Pollution 58 [66] Z. A. Ansari, S. G. Ansari, T. Ko, and J H. Oh, , Sensors and Actuators B, vol. 87 , p. 105, 2002. [67] C T. Wang and M T. Chen, Sensors and...