EXHIBIT 32.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the annual report of Airgas, Inc. (the "Company") on Form
10-K for the period ended March 31, 2005 as filed with the Securities and
Exchange Commission (the "Report"), I, Peter McCausland, Chairman and Chief
Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350,
as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to
such officer's knowledge:

      (1)   The Report fully complies with the requirements of section 13(a) or
            15(d) of the Securities Exchange Act of 1934; and

      (2)   The information contained in the Report fairly presents, in all
            material respects, the financial condition and results of operations
            of the Company as of the dates and for the periods expressed in the
            Report.

/s/ Peter McCausland
-----------------------------------------------
Peter McCausland
Chairman, President and Chief Executive Officer
(Principal Executive Officer)
June 13, 2005

The foregoing certification is being furnished to the Securities and Exchange
Commission pursuant to 18 U.S.C. Section 1350 as an exhibit to the Report and is
not being filed as part of the Report or as a separate disclosure document.