The length of hair and some synthetic fibers varies with the relative humidity of surrounding gases: the longer the relative humidity is, the longer the length is.
Most air pollution detectors use semiconductor sensors or formaldehyde sensors with poor accuracy (resolution 0.1 ppm), while the national standard is 0.08mg/m3 exceeding the standard, about 0.059 ppm...
Real-time on-line measurement of gas composition at combustion chamber outlet includes volume concentration and smoke number of UHC, CO, CO 2, NO, NO2, H2O, O2.