Abstract
Nondispersive infrared method (NDIR) is one of the most reliable and accurate methods for the measurement of cffrbon monoxide (CO) concentration in urban air. Detector tube method is widely used for the same purpose as a field method because of its simplicity. Four types of detector tube (A, B, C and G) are available in the market and, in this paper, the obtained CO values by the four detector tubes were compared with NDIR results as the reference. Type B and C of the tube gave slightly larger values and type G gave values agreeing with NDIR. The type A tube gave remarkably higher results, which were due to, probably, the influence of hydrocarbons in the sample air.
