Theoretical and field evaluation of a PM_2.5 high-volume impactor inlet design

A PM_2.5 high-volume impactor (HVI) sampler is developed, which has a flow rate of 1130 L per minute (lpm) (1.13 m³/min) and in it, the filter size used is of 8 inch × 10 inch. The major advantages of this sampler as compared to other low-volume sampler (flow rate 16.67 lpm) are lower uncertainty in mass measurement, higher PM_2.5 mass collection and lesser sampling time. To develop this PM_2.5 HVI sampler, a series of simulation and experimental studies were carried out. The optimized D₅₀ cutoff size of 2.52 μm was obtained experimentally under real ambient conditions (i.e. with polydisperse ambient particles) after the parametric adjustments. The commercial PM_2.5 HV sampler cutoff size was also evaluated experimentally, and agreed well to the D₅₀ cutoff size of developed PM_2.5 HVI sampler. Field performance studies of developed PM_2.5 HVI sampler were also carried out under both high- and low- particle mass loading conditions along with commercial PM_2.5 high- and low-volume samplers. The developed PM_2.5 HVI sampler agreed well with commercial PM_2.5 high- and low-volume samplers, i.e. PM_2.5 HVS, BAM and WINS reference sampler in mass measurement with mean deviations of 12.7, 18.5 and 11.7 μg/m³ (i.e. 5.05, 4.86 and 3.70%), respectively under tested conditions. This PM_2.5 HVI sampler is very useful especially where the extensive offline chemical analysis of filter samples/high amount of particulate material is needed for source apportionment studies or analysis of bioassay or toxicological purposes (in vitro/in vivo studies), diurnal studies, and air sampling where the mass concentration of particles is very low, e.g. marine, polar regions, most of the rural sites, etc.