Efficiency of a Tailor Made NO2 Passive Sampler and Correlations of NO2, PM10 and PM10 - bound NO3- in Urban Air of Chiang Mai (Thailand)

This work aims to find out the efficiency of simple equipment in comparison with automatic instruments for NO2 measurement, to analyze the correlations of air pollutants obtained from different techniques and to investigate the transformation of gaseous NO2 to particulate NO3- on PM10 particles. PM10 and NO2 samples (n = 47) were collected from the air quality monitoring (AQM) station containing automatic equipment in the urban area of Chiang Mai, Thailand, using both a mini volume air sampler and tailor made passive samplers. High correlations of the concentrations obtained from the two different techniques were observed for both PM10 (r = 0.98) and NO2 (r = 0.94). The results showed high efficiency of the tailor made passive samplers and a significant possibility of using them for NO2 measurement. PM10 and NO2 concentrations were also well correlated (r = 0.93). A correlation between the particulate phase (PM10 and PM10-bound NO3-) was very strong (r = 0.98), while a correlation between NO2 and NO3- (r = 0.90), was also high, which revealed transformation of the gas - to particle - phase on PM10 particles.