Document rxgaajXOnN0kro8YzyRJkVoMV

March 27, 1967 Mr. Victor H. Sussman Director, Division of Air Pollution Control Pennsylvania Air Pollution Commission P. O. Box 90 Harrisburg, Pennsylvania 17120 Dear Mr. Sussman: I realized last weeJc before the long holiday that I had not proposed any language as previously promised on the auto emission problem. Remembering your comments relative to avoiding the involvement of auto emissions in your proposed criteria, I would like to suggest the following addition to the footnote under Section 11 B: "In general, the criteria are based on a dosage concept and lequire both the presence of a receptor and an exposure time equal to or greater than those listed." This language should prevent some future misapplication of lead criteria to automobile emissions and I trust that it will be consistent with your disinclina tion to involve the proposed criteria with this subject at this time. Very truly yours. Charles E. Welch CEW:mvb