They collected dust in Los Angeles through an air filter. They found all sorts of pollution. They made no effort to determine the concentration of what they found in the air. SR 1419, what might be helpful is to determine the volume of air actually filtered, and then find the average concentration by dividing the mass collected by the volume filtered. Do what LAskywatch should have done.
From May 15, 2011 through August 15, 2011 one of our members ran a Honeywell HHT081 Hepa Air Filter in her backyard continually. The dust sample was gathered from the filter cartridge and submitted to American Scientific Laboratories, LLC for analysis.
That's about 90 days of air. They had a sample size of 0.25g However an air purifier probably does at least a cubic meter, or 1kg of air per hour, so that's 24*90 = 2160Kg, or about 2 million grams of air, or approximately 10 million times the weight of their sample.
So, divide all their results by at least 10,000,000.