Objectives of the study The purpose of the study was to investigate the possible causes of this problem; therefore the objectives of the study were: 1. To determine whether the burning activities in three neighboring countries infl uenced the increase in the PM10 level at all 13 measurement stations and 2. To determine whether the smoke and haze problem in Chiang Rai province was caused by trans-boundary smoke haze.
Data used in the study The data used in this study consisted mainly of the PM10 data and active fi re data. Other information, such as spatial data in a geographic information system (GIS) of provincial and national boundaries, was also utilized.