The numerical answer is wrong, but the level is above the limit.

Sulfur dioxide (SO2) is one of the principal pollutants that the Environmental Protection Agency (EPA) has listed in the National Ambient Air Quality Standards (NAAQS), as required by the Clean Air Act (40 CFR part 50). The level of SO2 in ambient air set by the NAAQS is 0.5 parts per million (ppm) by volume for an average time of 3 h to protect public welfare. Beyond that level the SO2 becomes a harmful pollutant to the environment. If the mass fraction of SO2 in ambient air at 20C is 0.53 mg/kg, determine whether the level of SO2 is above the limit set by the NAAQS. Given the density of air at 20C is 1.204 kg/m3 (Table A-15) and the molar masses of air and SO2 are 28.97 and 64.06 kg/kmol, respectively (Table A-1). The level of SO2 is NAAQS. 0.5 ppm that is above the limit set by the