A new sponge iron factory has an annual capacity of 100,000 tons/year of Iron production. Benzopyrene is produced during this process at a rate of 0.00006% of Iron produced. Due to high temperatures, 0.0003% Benzopyrene goes into the air. The space volume where iron smelting occurs is 100 m x 70 m x 7 m.
(a) The natural air flow rate to this industrial shade structure is 90 m3/hour. Determine the risk to the workers who work 8 hours/day, 50 weeks/year for 30 years. Assume workers are 75 kg and live for 70 years.
(b) What flow rate do you need to reduce the risk by 95%?