Along with rapid economic growth and enhanced agricultural productivity, particulate matter emissions inthe northern cities of Thailand have been increasing for the past two decades. This trend is expected to continuein the coming decade. Emissions of particulate matter have brought about a series of public health concerns,particularly chronic respiratory diseases. It is well known that lung cancer incidence among northern Thaiwomen is one of the highest in Asia (an annual age-adjusted incidence rate of 37.4 per 100,000). This fact hasaroused serious concern among the public and the government and has drawn much attention and interestfrom the scientific community. To investigate the potential causes of this relatively high lung cancer incidence,this study employed Fourier transform infrared spectroscopy (FTIR) transmission spectroscopy to identify thechemical composition of the PM2.5 collected using Quartz Fibre Filters (QFFs) coupled with MiniVol™ portableair samplers (Airmetrics). PM2.5 samples collected in nine administrative provinces in northern Thailand beforeand after the “Haze Episode” in 2013 were categorised based on three-dimensional plots of a principal componentanalysis (PCA) with Varimax rotation. In addition, the incremental lifetime exposure to PM2.5 of both genderswas calculated, and the first derivative of the FTIR spectrum of individual samples is here discussed.