RESUMO
The present study aimed at comparing some physical and chemical methods for measuring carbon monoxide [CO] level in air selecting the most suitable one concerning simplicity, reproducibility, sensitivity, specificity and accuracy. Known concentrations of CO were prepared in cylinders and air samples while unknown concentrations were collected in plastic bags from the street environment. Both known and unknown concentrations of CO were measured by four selected methods. The leucocrystal violet method was suitable only for levels of CO higher than 40 ppm and not recommended for ambient levels. The iodine pentoxide method was suitable for any level of CO in air but only for grab samples. The combustion method was also suitable for any level of CO above 10 ppm and for grab and continuous samples. MIRAN-IA analyzer is an infrared instrument, very simple, sensitive and accurate for concentrations of 10 ppm and above. Other types of infrared analyzers may give higher accuracy and sensitivity levels at lower concentrations