For each selected site, a local receptor grid is defined using Thailand provincial statistics and a geographical map. Then the power unit's emission parameters, together with meteorological data and receptor data entered into the ISCST model to calculate the increase of ambient concentrations of PM10 at each receptor location within the local range. Since within the local range the conversion of SO2 into SO4 is considered to be negligible, only the PM10 concentration is calculated.
The regional receptor grid is used for all four units under consideration. Table 4 also shows the result of regional modeling for the Mae Moh power unit. At the regional range, conversion of SO2 to SO4 becomes significant, and so, in addition to long-range PM10 concentration, the concentration of sulfate aerosol is also calculated. In calculation at the regional range, the pollutant concentrations of square No.5 are set to zero, to avoid double counting of regional and local effects.
The quantity of health damages by endpoints are obtained by multitplying the per capita risk factor by the increased concentration resulting from the modeling and by the population at the corresponding locations.The total health damages for each power unit are obtained by adding up the following two components