Country Site Vehicle Speed (km h-1 ) Equationz R2 Mexico Bolson 32 y = 448.34x-2.785 0.9093 Mexico Bolson 48 y = 102.63x-1.76 0.9358 Mexico Bolson 64 y = 3538.3x-3.459 0.9417 Mexico La Teja 32 y = 130.2x-1.892 0.7086 Mexico La Teja 48 y = 127.19x-1.796 0.8909 Mexico La Teja 64 y = 1406.7x-2.723 0.9304 Mexico Palomas 32 y = 8E+06x-4.425 0.9767 Mexico Palomas 48 y = 36667x-2.701 0.8236 Mexico Palomas 64 y = 7E+06x-0.4042 0.9738 USA Anthony 32 y = 1.0644x-0.847 0.9568 USA Anthony 48 y = 2.0482x-0.951 0.9544 USA Anthony 64 y = 4.7164x-1.219 0.9778 USA Columbus 32 y = 0.864x-1.137 0.9464 USA Columbus 48 y = 1.0093x-1.139 0.9678 USA Columbus 64 y = 1.7845x-1.249 0.9605 USA Deming 32 y = 10.495x-1.303 0.9500 USA Deming 48 y = 21.506x-1.512 0.9106 USA Deming 64 y = 24.672x-1.629 0.9725 USA Leyendecker 32 y = 0.9255x-1.06 0.9293 USA Leyendecker 48 y = 1.8354x-0.987 0.8716 USA Leyendecker 64 y = 2.8871x-0.948 0.9057 zy = mg PM2.5/m3, and x = time (seconds)

Table 5: The best fit power functions for the observed PM2.5 concentrations and times at each of three vehicle speeds for the seven experimental sites.