<PAGE>


                                 AMENDMENT NO. 1
                                       TO
                                RIGHTS AGREEMENT

     AMENDMENT NO. 1, dated as of May 13, 2004 (this "Amendment"), to the Rights
Agreement, dated as of December 13, 1995 (the "Rights Agreement"), between BHA
Group Holdings, Inc., a Delaware corporation (fka BHA Group, Inc.) (the
"Company"), and UMB Bank, N.A. (the "UMB").

                                R E C I T A L S:
                                - - - - - - - -

     A. Except as otherwise provided herein, capitalized terms used in this
Amendment have the meanings assigned to them in the Rights Agreement.

     B. In accordance with Section 21 of the Rights Agreement, on May 10, 2004,
Bank of America, N.A. resigned as the Rights Agent under the Rights Agreement.

     C. In accordance with Section 21 of the Rights Agreement, the Company may
appoint a successor Rights Agent.

     D. The Company desires to appoint UMB to act as agent for the Company in
accordance with the terms and conditions of the Rights Agreement as amended, and
UMB desires to accept such appointment.

     E. Pursuant to Section 26 of the Rights Agreement, the Company and UMB
desire to amend the definition of "Beneficial Owner" in the Rights Agreement.

     NOW, THEREFORE, in consideration of the herein premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

     1. Appointment of Successor Rights Agent. The Company hereby appoints UMB
to act as Rights Agent for the Company in accordance with the terms and
conditions of the Rights Agreement, as amended, and UMB hereby accepts such
appointment. All references in the Rights Agreement to Boatmen's Trust Company
shall be deemed to refer to UMB and any of its successors.

     2. Amendment to Rights Agreement.

     (a) Section 1(d) of the Rights Agreement is hereby amended to read in its
entirety as follows:

     "1(d) A Person shall be deemed the "Beneficial Owner" of, and shall be
     deemed to "beneficially own," any securities:

          (i) of which such Person or any of such Person's Affiliates or
     Associates is considered to be a "beneficial owner" under Rule 13d-3 of the
     General Rules and Regulations under the Exchange Act (the "Exchange Act



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     Regulations") as in effect on the date hereof; provided, however, that a
     Person shall not be deemed the "Beneficial Owner" of, or to "beneficially
     own," any securities under this subparagraph (i) as a result of an
     agreement, arrangement or understanding to vote such securities if such
     agreement, arrangement or understanding (A) arises solely from a revocable
     proxy given in response to a proxy or consent solicitation made pursuant
     to, and in accordance with, the applicable provisions of the Exchange Act
     and the Exchange Act Regulations, and (B) is not reportable by such Person
     on Schedule 13D under the Exchange Act (or any comparable or successor
     report);

          (ii) which are beneficially owned, directly or indirectly, by any
     other Person (or any Affiliate or Associate of such other Person) with
     which such Person (or any of such Person's Affiliates or Associates) has
     any agreement, arrangement or understanding (whether or not in writing),
     for the purpose of acquiring, holding, voting (except pursuant to a
     revocable proxy as described in the proviso to subparagraph (i) of this
     paragraph (d)) or disposing of such securities; or

          (iii) which such Person or any of such Person's Affiliates or
     Associates, directly or indirectly, has the right to acquire (whether such
     right is exercisable immediately or only after the passage of time or upon
     the satisfaction of conditions) pursuant to any agreement, arrangement or
     understanding (whether or not in writing) or upon the exercise of
     conversion rights, exchange rights, rights, warrants or options, or
     otherwise;

          provided, however, that under this paragraph (d) a Person shall not be
     deemed the "Beneficial Owner" of, or to "beneficially own," (A) securities
     tendered pursuant to a tender or exchange offer made in accordance with
     Exchange Act Regulations by such Person or any of such Person's Affiliates
     or Associates until such tendered securities are accepted for purchase or
     exchange, (B) securities that may be issued upon exercise of Rights at any
     time prior to the occurrence of a Triggering Event, (C) securities that may
     be issued upon exercise of Rights from and after the occurrence of a
     Triggering Event, which Rights were acquired by such Person or any of such
     Person's Affiliates or Associates prior to the Distribution Date or
     pursuant to Section 3(c) or Section 22 hereof (the "Original Rights") or
     pursuant to Section 11(i) hereof in connection with an adjustment made with
     respect to any Original Rights or (D) securities that were acquired in a
     transaction that was approved by the Board of Directors of the Company
     prior to the consummation of such transaction, unless thereafter the Person
     holding such securities acquires additional securities in a subsequent
     transaction that was not approved by the Board of Directors of the Company
     prior to the consummation of such subsequent transaction, whereupon such
     Person shall be deemed, as of the date of the consummation of the
     subsequent transaction, to be the "Beneficial Owner" of all securities held
     by such Person."



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     (b) Section 1(e) of the Rights Agreement is hereby amended by inserting the
words "or Kansas City, Missouri" after the words "New York City."

     (c) Section 18(a) of the Rights Agreement is hereby amended to read in its
entirety as follows:

     "(a) the Company agrees to pay to the Rights Agent reasonable compensation
     for all services rendered by it hereunder and, from time to time, on demand
     of the Rights Agent, its reasonable expenses, including reasonable fees and
     disbursements of its counsel, incurred in connection with the execution and
     administration of this Agreement and the exercise and performance of its
     duties hereunder. The Company shall indemnify the Rights Agent for, and
     hold it harmless against, any loss, liability, or expense, incurred without
     gross negligence, bad faith or willful misconduct on the part of the Rights
     Agent, for anything done or omitted by the Rights Agent in connection with
     the acceptance and administration of this Agreement, including the costs
     and expenses of defending against any claim of liability hereunder."

     (d) Section 20(b) of the Rights Agreement is hereby amended to read in its
entirety as follows:

     "(b) Whenever in the performance of its duties under this Agreement the
Rights Agent shall deem it necessary or desirable that any fact or matter
(including, without limitation, the identity of any Acquiring Person and the
determination of "current market price" or any dates or events defined in this
Agreement) be proved or established by the Company prior to taking or suffering
any action hereunder, such fact or matter (unless other evidence in respect
thereof be specified herein) may be deemed to be conclusively proved and
established by a certificate signed by any executive officer of the Company and
delivered to the Rights Agent; and such certificate shall be full authorization
to the Rights Agent for any action taken or suffered in good faith by it under
the provisions of this Agreement in reliance upon such certificate."

     (e) Section 20(c) of the Rights Agreement is hereby amended to read in its
entirety as follows:

     "(c) The Rights Agent shall be liable hereunder only for its own gross
     negligence, bad faith or willful misconduct."

     (f) Section 21 of the Rights Agreement is hereby amended to delete the
requirement that the any successor Rights Agent, including the Rights Agent,
"shall be authorized to do business as a banking institution in the State of New
York" and forthwith there shall be no such requirement.

     (g) Section 25 of the Rights Agreement is hereby amended to delete
Boatmen's Trust Company as the notice addressee for the Rights Agent, and
replace it with the following address:

     "UMB Bank, N.A.


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     2401 Grand Blvd.
     Kansas City, Missouri, 64108
     Attn: Corporate Trust Department"

     3. Governing Law. This Amendment shall be construed according to, and the
rights and liabilities of the parties shall be governed by, the laws of the
State of Delaware, without regard to the conflict of laws principles thereof.

     4. Entire Agreement and Amendment. This Amendment, together with the Rights
Agreement, represents the entire agreement between the parties with respect to
the subject matter of this Amendment and the Rights Agreement, and may not be
changed, modified or terminated except by an instrument in writing signed by the
Company and the Rights Agent. Except as specifically set forth in this
Amendment, the Rights Agreement shall remain unmodified and in full force and
effect.

     5. Binding Effect. This Amendment shall be binding upon and inure to the
benefit of the parties and their respective successors and permitted assigns.

     6. Counterparts. This Amendment may be delivered by facsimile and executed
in counterparts, each of which shall constitute an original and all of which
together shall constitute one and the same instrument.

                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]



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     IN WITNESS WHEREOF, the parties have executed this Amendment as of the date
first above written.

                                                 BHA GROUP HOLDINGS, INC.


                                                 By:
                                                     ---------------------------
                                                     Name:
                                                     Title:


                                                 UMB BANK, N.A.


                                                 By:
                                                     ---------------------------
                                                     Name:
                                                     Title:


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