In the presence of high concentrations of ammonia and nitric acid gas, the formation of ammonium nitrate particles (NH 4 NO 3) is well established at low temperatures. As a result, high concentrations of ammonium nitrate particles are usually observed during the spring and winter period. Due to its semi-volatile nature, the measurement of ammonium nitrate with classical methods based on filter sampling (sampling time ≥ 24 h) introduce severe artifacts. Thus, the main objective of this study is to develop new low-cost sensors able to measure simultaneously and selectively the concentration of ammonium nitrate particles and its gaseous precursor ammonia. Sensors combine two surfaces which are sensitive to ammonia and based on polyaniline nanocomposites materials. The mass concentration of ammonium nitrate is determined by measuring the concentration of the ammonia released by heating one of the sensitive surfaces. Sensors show a response to gaseous ammonia at concentrations less than 20 ppb with sensitivity around 0.3 %.ppb-1 , and the limit of detection of sensors to ammonium nitrate particles is around 270 µg.m-3 with a sensitivity of 0.0014 %.µg-1 .m 3 .