A building is contaminated with Styrene. The concentration is $3500$ ppm$.$ The building's

dimensions is $304020ft.$ The effective air flow is $400f\frac{t^3}{m}in.$

a$.$ What will the concentration be after $20$ minutes of ventilation? $(4$ points$)$

b$.$ Is there still health hazard? $(1$ point$)$

c$.$ How long will it take from initial condition to reduce the contamination to $10\%$ of its

OSHA required level? $(3$ points$)$

A container of styrene is broken and $90c{m}^3$ of this material is evaporated into the air in a

room with safety factor of $2\mathrm{.}0$ during $2\mathrm{.}5$ hours. Calculate the airflow for diluting the

contamination to $25\%$ of the OSHA PEL. $(4$ points$)$