Nitrogen dioxide gas is sensed in {HEAD ~ accordance} with {TAIL ~ a color change} before and after the sensor element is exposed to air to be measured for a predetermined time 
with
Nitrogen dioxide gas is sensed in { HEAD ~ accordance } with { TAIL ~ a color change } before and after the sensor element is exposed to air to be measured for a predetermined time
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH