Coated filters were developed to replace the glass impinger methods that use reagent solutions. The purpose of this study was to simultaneously measure nitrogen dioxide (NO₂) and respirable suspended particles (RSP) by a filtration method with a cyclone connected to a pump. A first pre-filter for RSP and second filter for NO₂, which was soaked in a TEA (Triethanolamine) solution, were loaded into a filter cassette with a pump flow rate of 1.7 l/m. After sampling, the TEA soaked filter was removed from the cassette, placed in a large test tube (10 ml), mixed, and allowed time to develop. The absorbance (abs) of the diazo compound of the NO₂ and N-(1-Napthylethylenediamine dihydrochloride) in the color reagent was measured at 545 nm on a spectrophotometer. The collection efficiency(%) of NO₂ by each 3 filter soaked in TEA solution and used in the cyclone with a pump flow rate 1.7 l/m was 893% and the correlation coefficient between the true NO₂ concentration and that determined by the TEA soaked filters was 0.993(p<0.001).