Catalogues, journals and reference books. PO Boxes are far safer. But in intensely polluted environments like Hong Kong excluding or controlling particles and gases from homes sufficiently to protect health is difficult. The idea that filtering would make a difference to our overall exposures and risk in Hong Kong is probably pie in the sky. I am for " We The People" who are you for??? The respirator should only have to deal with the traces that escape the primary systems. Indeed, research suggests that in Hong Kong, it results in more than 3, deaths and seven million doctor visits per year.
For the first time since the early 90's all of my Family and Friends are gainfully employed!!!
Mostly it was about nostalgia and regret. Proudly display your latest creation. The respirator should only have to deal with the traces that escape the primary systems. Thanks again to the knowledgeable and helpful members of the board! Others chiefly filter out particulates, the best being high-efficiency particulate air HEPA filters, and these may be the preferred option for trying to reduce air pollution at home.