Each interquartile increase ( 10,850 / cm ) in UFP exposure was associated with a 4.91 % ( 95 % CI : -9.31 , -0.512 ) decrease in reactive hyperemia index ( a measure of micro-vascular function ) and each 24 ppb increase in O exposure corresponded to a 2.49 % ( 95 % CI : 0.141 , 4.84 ) increase in systolic blood pressure and a 3.26 % ( 95 % CI : 0.0117 , 6.51 ) increase in diastolic blood pressure 3-hours after exposure .