A stand-off laser-induced breakdown spectroscopy (LIBS) system was developed to determine the elemental composition of contamination particles during semiconductor manufacturing. It successfully detected laboratory-generated monodisperse (size=200 nm and 300 nm) CaCl2 particles and internally mixed particles of CaCl2, MgCl2, NaCl, and KCl. Temperature and pressure effects on the LIBS emission signals were investigated. The peak area and signal-to-noise ratio of the emission lines increased with the temperature (25°C-250°C). Stronger emission lines were observed at higher pressure. Although temperature and pressure affect the LIBS signals, the developed stand-off LIBS could be employed for real-time detection of the elemental composition of contamination particles.