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