Bleach on Concrete To the Editor: In the item “Fixing a Moldy Crawlspace” (On the House, 12/00), Bill Rose cautions not to use bleach around concrete, because “when bleach comes in contact with anything having a pH less than 8, chlorine gas is formed.” Now I am no scientist, but I do recall that concrete has a pH of around 12 to 13. I contacted the Chlorine Institute to confirm my findings and they stated that they did not know of anything in concrete that would cause the release of chlorine gas. However, Mr. Rose is correct about the release of chlorine gas when bleach comes in contact with anything having a pH less than 8. David Patrician via e-mail Bill
