2002-03-06 The Environmental Protection Agency set average annual limits at 15 micrograms per cubic meter in 1997, when it tightened its standards to include fine particulate matter - pollutants measuring less than 2.5 micrometers. That is about 1/28th the width of a human hair.
That must mean the author figured the human hair is 70 �m thick. Yes, the need to compare 2.5 �m to the thickness of the human hair is somewhat strange, as most people wouldn't know how thick hair is if their life depended on it. But, then again, one can see how thick hair is and to imagine that something can be 28 times smaller is awe inspiring. At least to the author. Also note the lack of using symbols. Why not write it as 15 �g/m^3? John ----- Original Message ----- From: "M R" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Wednesday, 2002-03-06 08:43 Subject: [USMA:18560] Pollution article:Weird fraction > An article on pollution in American cities @ > http://story.news.yahoo.com/news?tmpl=story&cid=534&u=/ap/20020305/ap_on_he_ me/pollution_lung_cancer > > is fully in SI except for this sentence with a weird > fraction. > '2.5 micrometers. That is about 1/28th the width of a > human hair.' > First of all human hair differs from person to person > and from male and female, so what makes them give such > a precision of 1/28. Do the Americans love the > fractions. > Anyway please read it for the sake of health of > yourself and your family. Metric people will love it > since it is 100 % SI. > > Madan > > > __________________________________________________ > Do You Yahoo!? > Try FREE Yahoo! Mail - the world's greatest free email! > http://mail.yahoo.com/ >
