Answer Happy

Problem 3 (20 points) Air Pollution: Indoor Air Quality A single-story home with infiltration rate of 0.5 ach has 200 m² of floor space and a total volume of 500 m². (i) (10 points) If 0.6 pCi/m-s of radon is emitted from the soil and enters the house, write the steady-state material balance for radon in the house. Radon is a radioactive gas that follows first-order decay with rate constant of 0.0076 per hour. The natural outdoor level of radon gas is 0.4 pCi/L. The unit pCi is equal to 107 of curie (Ci), which is a common measurement of radioactivity. (ii) (8 points) Based on the material balance you wrote in (i), estimate the steady-state indoor radon concentration in pCi/L. (iii) (2 points) Check briefly the EPA's assessment of risks from radon in homes provided in the table below. From the table, you can see that 23 persons out from the general population will die from lung cancer due to natural outdoor radon levels. The 10,000 persons numbers are higher for people who smoke, or who have smoked in the past, due to a strong combined effect of smoking and radon. Do you think that the radon concentration you found in (ii) will increase significantly the lifetime risk of lung cancer death of a person who lives in this house? Give a brief justification of your answer. Radon Level Lifetime Risk of Lung Cancer Death (per person) from Radon Exposure In Homes PCI/L Never Smokers Current Smokers General Population 20 36 out of 1,000 26 out of 100 11 out of 100 10 18 out of 1,000 15 out of 100 56 out of 1,000 8 15 out of 1,000 12 out of 100 45 out of 1,000 4 73 out of 10,000 62 out of 1,000 23 out of 1,000 2 37 out of 10,000 32 out of 1,000 12 out of 1,000 1.25 23 out of 10,000 20 out of 1,000 73 out of 10,000 0.4 73 out of 100,000 64 out of 10,000 23 out of 10,000 Assumes constant lifetime exposure in homes at these levels. From https://www.epa.gov/radon/health-risk-radon In your solution, draw a schematic of the system, state all your assumptions, and show details of your calculations.