Time-series data on PM10 (particulate matter less than or equal to 10 μm in size) readings
obtained from 13 measurement stations belonging to the Pollution Control Department of Thailand and
moderate resolution imaging spectroradiometry (MODIS) and fi re-related data (MOD14) were analyzed.
The study investigated the relationships of the haze-and-smoke distribution characteristics and trends
with the number of active fi res in the dry season (from January to April) in 2009, 2010 and 2012. The
study was conducted at the regional and local levels to investigate smoke and haze dispersion due to
burning activities in three neighboring countries and also within Chiang Rai province itself. Various
techniques and tools were applied, including methods based on using a geographic information system
to produce buffer zones around the Chiang Rai measurement station with an incremental radius of 10
km. The hybrid-single particle Lagrangian integrated trajectory (HYSPLIT) model was also used to
investigate the long-range movement of smoke and haze from neighboring areas to the province