Measurement of Air Quality 38319.2 A hi-vol clean filter weighs 20.0 g. After exposure in the sampler for 24 h,
the filter (now dirty) weighs 20.5 g. The initial and final air flows through the hi-vol
sampler were 70 and 50 ft3/min, respectively. What was the concentration of parti-
culate matter in the air? Were any National Ambient Air Quality Standards exceeded?
(See Chap. 21.)
19.3 A hi-vol sampler draws air at an average rate of 70 ft3/min. If the measured
particle concentration is 200 pg/m3 and the hi-vol sampler was operated for 12 h, what
was the weight of dust on the filter?