A high-efficiency filter is being used to remove particles that have a mass median diameter (MMD) of 2.5 microns and a density of 2.2 g/cm3. The air temperature is 40 C. The 24-hour PM2.5 dust concentration (Ci) is 50% lower than the norm value of a country-X. The filter speed is 0.025 m/s. Clean filter pressure drop is 0.1 inch H2O.

a) Determine the filtration time in months required for the filter to reach a pressure drop of 1.5 inH2O.

b) Determine the filtration time if the air temperature is -2C? conclude