Note : NAAQS Standards can be found online. Please answer fully and correctly an

Question

Note : NAAQS Standards can be found online. Please answer fully and correctly and I will highly rate.

The NAAQS standards (page 583) are listed only as ppm by the EPA except for Pb and PM which are in g m-3. The table shows units of g m-3 as well as ppm for most pollutants a) Why is ppm not shown for PM? b) If ozone is at the ppm limit on a really hot day in St. Louis, 108° F, what 1. concentration in g m-3 is that ozone? If the temperature drops to 88°F that night, what is the concentration in g m c)

Explanation / Answer

a)Pm stands for particuate matter and is a term for mixture of solid particles and liquid droplets present in air. PM generally contains particles of various sizes . PM10 denotes partciles that are with diameters 10 micrometers and smaller. Particulate matter can be measured by making a count of the number of particles present in a unit volume of air, PM cannot be expressed in ppm since there are various ranges of particle sizes and characterised by weight; hence most appropriate way of expressing PM is by weight per unit volume i.e mg/m3 or ug/m3.

b)As per NAAQS table, ozone maximum level = 0.070 ppm

we have concentration in ug/m3 = (concentration in PPM * Molar mass in mg/mole)/(1000*0.08205 T(in kelvin))

given T= 108 deg Fahrenheit = 315.372 K; Molar mass of ozone = 48*10^3 mg/mole

Conc of O3 in ug/m3 = (0.070*48*10^3)/(1000*0.08205*315.372) = 0.1298 ug/m3

c) T= 88 deg Fahrenheit = 304.261 k

Conc of O3 = (0.070*48*10^3)/(1000*0.08205*304.261) = 0.1345 ug/m3

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