You are operating an instrument that pulls air through a particle filter at a flow rate of 16.7 L/min (1 m^3/hr). There is animpactor upstream of the filter that removes particles with aerodynamic diameters > 2.5 mm. Before you start sampling atmospheric air, the filter weighs 80 mg. After sampling for 24hours, the filter weighs 80.7 mg. Neglecting potential measurementerrors, what is the average concentration of PM2.5 in theatmosphere for this 24-hr period?
Briefly discuss possible errors associated with the measurement described in this question.