I'm not a native English speaker. I didn't get what is wrong with the sentence
> “States were further required to limit soot from power plants, cars and other sources to 2.5 microns, or 28 times smaller than [who can be sure what this means?] the width of a human hair.”
that is quoted in the text. Should they have said "soot particles"? Or is it something else? And why can't we be sure what "28 times smaller than" means?
> “States were further required to limit soot from power plants, cars and other sources to 2.5 microns, or 28 times smaller than [who can be sure what this means?] the width of a human hair.”
that is quoted in the text. Should they have said "soot particles"? Or is it something else? And why can't we be sure what "28 times smaller than" means?