Document:

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                                                                   EXHIBIT 10.37

                              STOCK SALE AGREEMENT
                              --------------------

         This agreement (the "Agreement") is made as of the /s/ 5th day of /s/
July, 2000 by and between Hilary Taub (the "Seller"), and CECO Environmental
Corp. (the "Purchaser").

                                    RECITALS:

         A. The Seller desires to sell 124,703 shares of the common stock of the
Purchaser (the "Shares") for $2.125 per share.

         B. Purchaser desires to purchase the Shares.

                                   AGREEMENT:

         NOW, THEREFORE, in consideration of the mutual representations,
warranties and undertakings contained herein, the parties hereto agree as
follows:

         11. Sale and Purchase of Shares. In accordance with the terms and
subject to the conditions contained herein, the Purchaser hereby agrees to
purchase from the Seller and the Seller hereby agrees to sell to the Purchaser
the Shares for aggregate purchase consideration of $264,993.88 (the "Purchase
Price").

         12. The Closing. The closing (the "Closing") shall occur on June 30,
2000. On the date of the Closing the Seller shall deliver to the Purchaser
certificates representing the Shares ("Certificates") endorsed in blank or
accompanied by assignments separate from certificate sufficient to transfer the
Shares into the name of Purchaser and Purchaser shall deliver to the Seller the
Purchase Price by certified check or immediately available funds via wire
transfer.

         13. Representations and Warranties of the Seller. The Seller hereby
represents and warrants to the Purchaser as follows:

            3.1 Authority Relative to this Agreement. The Seller has the
authority to enter into this Agreement. This Agreement has been duly executed
and delivered by the Seller and is a valid and binding Agreement enforceable in
accordance with its terms except as such enforcement is subject to bankruptcy,
insolvency, reorganization or other laws relating to or affecting the
enforcement of creditors' rights generally.

            3.2 No Violation or Conflict. Neither the execution nor the
consummation of this Agreement will violate or result, with the giving of notice
or lapse of time, or both, in a violation of or result in the acceleration of or
entitle any party to accelerate (whether after the giving of notice or lapse of
time or both) any obligation under, or result in the creation of imposition of
any lien, charge, pledge, security interest or other encumbrance upon the
property of the Seller pursuant to any provision of any contract, agreement,
note, mortgage, lien, indenture, license, lease, other instrument, law,
ordinance, regulation, arbitration, order, judgment or decree to which the
Seller is a party or by which it, or its property is bound, or permit the
termination of any agreement, instrument, lien, license, lease or mortgage to
which the Seller is a party.

<PAGE>

            3.3 Court Orders, Decrees and Laws. There is no outstanding or, to
the Seller's knowledge, threatened, order, writ, injunction or decree of any
court, government agency or arbitrational tribunal against or affecting the
Seller or any of its assets that would significantly interfere with the Seller's
ability to consummate the transaction contemplated by this Agreement.

            3.4 Absence of Litigation. There is no action, suit, proceeding,
claim, arbitration or investigation pending or, to the best knowledge of the
Seller, threatened or contemplated by any person including, without limitation
any governmental or regulatory agency, against the Seller or with respect to the
assets of the Seller or which seeks to prohibit, restrict or delay consummation
of this Agreement or the transactions contemplated hereby. There is no factual
basis known to the Seller which is known to present a possibility for any such
action, suit, proceeding, claim, arbitration or investigation.

            3.5 Encumbrances. Seller has good and marketable title to the Shares
free and clear of all liens, charges, encumbrances, security interests and
claims whatsoever.

            3.6 Status of Seller. Seller has been given access to all the
information that Seller considers necessary or appropriate for deciding whether
to sell the Shares. Seller further represents that she has had an opportunity to
ask questions and receive answers from Purchaser regarding the business,
properties, prospects and financial condition of the Purchaser and its
affiliates, including without limitation from Steven I. Taub, an executive
officer of CECO Filters, Inc.

         14. Representations, Warranties and Covenants of the Purchaser. The
Purchaser hereby represents and warrants to the Seller as follows:

            4.1 The Purchaser. The Purchaser is a corporation duly organized and
validly existing under the laws of the State of New York and has all requisite
right, power and authority necessary to own, lease and operate all of its
property and to carry on its business as it is now being carried on.

            4.2 Authority Relative to the Contracts. The Purchaser has the
authority to enter into this Agreement. This Agreement has been duly executed
and delivered by the Purchaser and is a valid and binding Agreement enforceable
in accordance with its terms except as such enforcement is subject to
bankruptcy, insolvency, reorganization or other laws relating to or affecting
the enforcement of creditors' rights generally.

            4.3 No Violation or Conflict. Neither the execution nor the
consummation of this Agreement will violate any provision of the articles of
organization or operating agreement of the Purchaser or violate or result, with
the giving of notice or lapse of time, or both, in a violation of or result in
the acceleration of or entitle any party to accelerate (whether after the giving
of notice or lapse of time or both) any obligation under, or result in the
creation of imposition of any lien, charge, pledge, security interest or other
encumbrance upon the property of the Purchaser pursuant to any provision of any
contract, agreement, note, mortgage, lien, indenture, license, lease, other
instrument, law, ordinance, regulation, arbitration, order, judgment or decree
to which the Purchaser is a party or by which it, or its property is bound, or
permit the termination of any agreement, instrument, lien, license, lease or
mortgage to which the Purchaser is a party.

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            4.4 Court Orders, Decrees and Laws. There is no outstanding or, to
the Purchaser's knowledge, threatened, order, writ, injunction or decree of any
court, government agency or arbitrational tribunal against or affecting the
Purchaser or any of its assets that would significantly interfere with the
Purchaser's ability to consummate the transaction contemplated by this
Agreement.

            4.5 Absence of Litigation. There is no action, suit, proceeding,
claim, arbitration or investigation pending or, to the best knowledge of the
Purchaser, threatened or contemplated by any person including, without
limitation any governmental or regulatory agency, against the Purchaser or with
respect to the assets of the Purchaser or which seeks to prohibit, restrict or
delay consummation of this Agreement or the transactions contemplated hereby.
There is no factual basis known to the Purchaser which is known to present a
possibility for any such action, suit, proceeding, claim, arbitration or
investigation.

         15. Conditions Precedent to Obligations of the Purchaser. Consummation
of the transaction contemplated hereby on the part of the Purchaser is subject
to the fulfillment, to the reasonable satisfaction of the Purchaser, of each of
the following conditions:

            5.1 Representations True at Closing. The representations and
warranties of the Seller contained in Section 3 of this Agreement shall be true
in all material respects on the date hereof and at the time of the delivery of
the Certificates.

            5.2 Litigation. No litigation or proceeding shall be pending or
threatened to restrain, set aside or invalidate the transactions contemplated by
this Agreement.

            5.3 Separation Agreement. Seller has entered into and is not in
default of that certain Separation Agreement among Purchaser, Seller and CECO
Filters, Inc.

            5.4 Steven I. Taub Agreement. Steven I. Taub has entered into and
performed his obligations pursuant to a Stock Purchase Agreement among Steven I.
Taub, CECO Filters, Inc. and Purchaser in form satisfactory to Purchaser.

         16. Conditions Precedent to Obligations of the Seller. Consummation of
the transactions contemplated hereby on the part of the Seller is subject to the
fulfillment, to the reasonable satisfaction of the Seller of each of the
following conditions:

            6.1 Representations True at Closing. The Purchaser's representations
and warranties contained in Section 4 of this Agreement shall be true in all
material respects at the date hereof and at the time of the delivery of the
Certificates.

            6.2 Litigation. No litigation or proceeding shall be pending or
threatened to restrain, set aside or invalidate the transactions contemplated by
this Agreement.

<PAGE>

         17. Survival of Representations, Warranties, Covenants and Agreements.
All warranties, representations, covenants and agreements made hereunder shall
survive the Closing.

         18. Termination. If any of the conditions for the consummation by the
Seller or the Purchaser of the closing of the transactions hereunder shall not
have been fulfilled (despite the best efforts of the party, if any, obligated to
fulfill such condition) or waived by July 15, 2000, then this Agreement may
thereafter be terminated by any party hereto. Such termination hereunder shall
be effected by notice by the terminating party to the other parties hereunder,
and upon such termination this Agreement shall be without further force and
effect, and no party hereto shall be liable to any other for any claim, damage,
cost or expense arising from the execution and delivery of this Agreement or the
failure to consummate the transactions contemplated hereby.

         19. Remedies. The parties hereto, in addition to being entitled to
exercise all rights provided herein or granted by law, including recovery of
damages, shall be entitled to specific performance of their rights under this
Agreement and all other appropriate equitable remedies. The parties agree that
monetary damages would not be adequate compensation for any loss incurred by
reason of a breach of the provisions of this Agreement, and hereby agree to
waive the defense, in any action for specific performance, that monetary damages
would be adequate compensation. The parties hereto further agree that in the
event of any breach of this Agreement, the breaching party shall be liable for
all damages arising as a consequence of such breach, including without
limitation, costs and expenses (including, without limitation, attorneys' fees),
incurred by the non-breaching party in attempting to enforce its rights
hereunder.

         20. Miscellaneous. It is the understanding of the parties hereto that:

            10.1 Waiver. Any party may, at its option, waive in writing any or
all of the conditions herein contained to which its obligations hereunder are
subject.

            10.2 Expenses. Each party hereto shall bear its own expenses in
connection with this Agreement and the transactions contemplated herein.

            10.3 Entire Agreement. This Agreement sets forth the entire
understanding of the parties and supersedes all prior agreements, arrangements
and communications, whether oral or written, with respect to the subject matter
hereof. This Agreement shall not be modified or amended except by written
agreement of the parties hereto. Captions appearing in this Agreement are for
convenience only and shall not be deemed to explain, limit or amplify the
provisions or contents hereof.

            10.4 Severability. The invalidity or unenforceability of any
particular provision of this Agreement shall not affect the other provisions
hereof, and this Agreement shall be construed in all respects as if the invalid
or unenforceable provision were omitted.

            10.5 Binding Effect; Assignment. All the terms, provisions,
covenants and conditions of this Agreement shall be binding upon and inure to
the benefit of and be enforceable by the parties hereto and their respective
heirs and successors. This Agreement and the rights and obligations of the
parties hereto shall not be assigned or delegated by any party hereto without
the written consent of the other parties hereto.

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            10.6 Notices. Any notice or other instrument or thing required or
permitted to be given, served or delivered to any of the parties hereto shall be
in writing and shall be considered given when hand-delivered to the recipient,
or when delivered to an internationally recognized courier service, or when
deposited with the U.S. Postal Service using certified mail, postage prepaid,
addressed to the recipient at:

         The Seller:

                  Hilary Taub

                  ___________________________

                  ___________________________

         The Purchaser:

                  CECO Environmental Corp.
                  505 University Avenue
                  Suite 1400
                  Toronto, Ontario M5G 1X3
                  Canada
                  Attn:  Phillip DeZwirek

         with a copy to:

                  Leslie J. Weiss, Esq.
                  Sugar, Friedberg & Felsenthal
                  30 North LaSalle Street
                  Suite 2600
                  Chicago, Illinois 60602

or at such other address as a party may designate to another party in accordance
with the terms of this Section 10.6.

            10.7 Governing Law. This Agreement shall be governed by and
construed in accordance with the internal laws (as opposed to its rules
governing conflicts of laws) of the State of Pennsylvania.

            10.8 Counterparts. This Agreement may be executed in counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.

            10.9 Costs and Attorneys' Fees. If either party to this Agreement
institutes a legal action to enforce its rights under any provision of this
Agreement, the non-prevailing party in such action shall be liable to the
prevailing party for the costs and reasonable attorneys' fees incurred by the
prevailing party in connection with the action.

<PAGE>

            IN WITNESS WHEREOF, the parties hereto have executed this Agreement
as of the date first set forth above.

                                            CECO Environmental Corp.

                                                 By: /s/ Phillip DeZwirek
                                                     ---------------------------
                                                 Its: /s/ Chairman & CEO
                                                     ---------------------------
 .

                                                     /s/ Hilary Taub
                                                     ---------------------------
                                                         Hilary Taub<PAGE>

                                                                   EXHIBIT 10.38

NEITHER THIS NOTE NOR ANY SECURITIES WHICH MAY BE ISSUED UPON THE EXERCISE OF
THE WARRANTS HEREOF HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR REGISTERED OR OTHERWISE QUALIFIED UNDER ANY STATE SECURITIES LAW.
NEITHER THIS NOTE NOR ANY SUCH SECURITIES MAY BE SOLD OR OFFERED FOR SALE IN THE
ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT UNDER SAID ACT AND REGISTRATION
OR OTHER QUALIFICATION UNDER ANY APPLICABLE STATE SECURITIES LAWS, OR AN OPINION
OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION OR OTHER
QUALIFICATION IS NOT REQUIRED.

THIS NOTE IS SUBJECT TO THE TERMS OF THE SUBORDINATION AGREEMENT (AS DEFINED
HEREIN IN SECTION 8) IN FAVOR OF PNC BANK, NATIONAL ASSOCIATION, AS AGENT FOR
CERTAIN BANKS. NOTWITHSTANDING ANY CONTRARY STATEMENT CONTAINED IN THE WITHIN
INSTRUMENT, NO PAYMENT ON ACCOUNT OF ANY OBLIGATION ARISING FROM OR IN
CONNECTION WITH THE WITHIN INSTRUMENT OR ANY RELATED AGREEMENT (WHETHER OF
PRINCIPAL, INTEREST OR OTHERWISE) SHALL BE MADE, PAID, RECEIVED OR ACCEPTED
EXCEPT IN ACCORDANCE WITH THE TERMS OF THE SUBORDINATION AGREEMENT.

                            CECO Environmental Corp.
                                   REPLACEMENT
                                 PROMISSORY NOTE

$4,000,000                                                       March 12, 2001

         WHEREAS, Green Diamond Oil Corp., an Ontario corporation ("Green
Diamond") has prior to this date advanced $4,000,000 (the "Advance") to CECO
Environmental Corp.

         WHEREAS, the terms of the Advance are set forth in a Promissory Note
dated December 7, 1999, (the "Original Note"), which Original Note shall be
cancelled and replaced by this Replacement Promissory Note.

         FOR VALUE RECEIVED, the undersigned, CECO Environmental Corp. (the
"Company"), a New York corporation, hereby promises to pay to the order of Green
Diamond or registered assigns ("Holder"), the principal sum of FOUR MILLION
DOLLARS ($4,000,000) on the Maturity Date, as defined in Section 1 below. This
Note is part of a series of Notes of like tenor and effect to this Note in the
aggregate principal amount of $5,000,000 issued in connection with a financing
by the Company (the "1999 Subordinated Notes").

         1. Maturity. This Note shall be due and payable upon the earlier to
occur of the following events (the "Maturity Date"): (i) six and one-half (6
1/2) years from the December 7, 1999; (ii) six (6) months after repayment of the
Superior Debt (as defined in Section 8 below); or (iii) the closing (any such
closing referred to as the "Closing") of a Sale Transaction. For purposes of
this Note, a Sale Transaction shall mean (i) a merger, consolidation, corporate
reorganization, or sale of shares of stock of the Company as a result of which
there is a change in control and/or the shareholders of the Company on the date
hereof ("Current Shareholders") own 50% or less of the outstanding shares of the
Company on a fully-diluted basis immediately after the transaction and,
including as outstanding for purposes of such calculation, any warrants, options
or other instruments convertible or exchangeable into equity securities of the
Company issued to persons other than the Current Shareholders in connection with
the transaction or (ii) the sale of (A) fifty percent or more of the assets of
the Company or (B) any subsidiary, division or line of business of the Company
for total consideration in excess of $5 million.
<PAGE>

         2. Interest. Interest shall accrue on the unpaid principal balance
hereof and on any interest payment that is not made when due at the simple
compounded rate of twelve percent (12%) per annum from the date hereof. Accrued
Interest shall be due and payable on June 30 and December 31 of each year
commencing June 30, 2000 and on the Maturity Date. Notwithstanding the
foregoing, interest due under this Note on June 30, 2000 and December 31, 2000,
will be paid in accordance with the terms of the Subordination Agreement. It
shall not be a default hereunder and interest will not accrue on any portion of
such interest payments deferred pursuant to the Subordination Agreement
("Deferred Interest") so long as the Deferred Interest is paid at the time and
in the manner allowed by the Subordination Agreement. In the Event of Default
(as defined herein), interest shall accrue on all unpaid amounts due hereunder
including without limitation, interest, at the rate of fifteen percent (15%) per
annum. If a judgment is entered against the Company on this Note, the amount of
the judgment so entered shall bear interest at the highest rate authorized by
law as of the date of the entry of the judgment.

         3. Payments. Payments of both principal and interest shall be made at
the principal executive office of the Company, or such other place as the holder
hereof shall designate to the Company in writing, in lawful money of the United
States of America.

            So long as no Event of Default has occurred in this Note, all
payments hereunder shall first be applied to interest, then to principal. Upon
the occurrence of an Event of Default in this Note, all payments hereunder shall
first be applied to costs pursuant to Section 13.5, then to interest and the
remainder to principal.

         4. Registration, Transfer and Exchange of Notes. The Company will keep
at its principal office a register in which it will provide for the registration
of and transfer of this Note, at its own expense (excluding transfer taxes). If
any Note is surrendered at said office or at the place of payment named in the
Note for registration of transfer or exchange (accompanied in the case of
registration of transfer or exchange by a written instrument of transfer in form
satisfactory to the Company duly executed by or on behalf of the holder), the
Company, at its expense, will deliver in exchange one or more new Notes in
denominations of $10,000 or larger multiples of $1,000, as requested by the
holder for the aggregate unpaid principal amount. Any Note or Notes issued in a
transfer or exchange shall carry the same rights to increase Notes surrendered.
The Holder agrees that prior to making any sale, transfer, pledge, assignment,
hypothecation, or other disposition (each, a "Transfer") of the Note, the Holder
shall give written notice to the Company describing the manner in which any such
proposed Transfer is to be made and providing such additional information and
documentation regarding the Transfer as the Company reasonably requests. If the
Company so requests, the Holder shall at his expense provide the Company with an
opinion of counsel (which counsel must be reasonably satisfactory to the
Company, to the holder, in form and substance satisfactory to the Company) that
the proposed Transfer complies with applicable federal and state securities
laws. The Company shall have no obligation to Transfer any Notes unless the
holder thereof has complied with the foregoing provisions, and any such
attempted Transfer shall be null and void.
<PAGE>

         5. Registered Owner. Prior to due presentation for registration of
transfer, the Company may treat the person in whose name any Note is registered
as the owner and holder of such Note for the purpose of receiving payment of
principal of, and interest on, such Note and for all other purposes.

         6. Conversion.

            a. Conversion Procedure.

                (1) At any time and from time to time, the Company may elect to
      convert all or any portion of the unpaid principal balance on any 1999
      Subordinated Note into the number of shares of common stock of the
      Company, $0.01 par value per share ("Common Stock") computed by
      multiplying the unpaid principal balance to be converted times $1.00 per
      share and dividing the result by the 1999 Subordinated Note Conversion
      Price determined pursuant to Section 6.b. The Company shall pay to the
      holder of each 1999 Subordinated Note so converted, all accrued and unpaid
      interest in cash or, at the Company's option, in Common Stock valued at
      Fair Market Value, at the time of conversion with respect to such 1999
      Subordinated Note so converted with no further interest accruing or
      payable on the converted portion of the 1999 Subordinated Note.

                (2) Each conversion of all or any portion of a 1999 Subordinated
      Note will be deemed to have been effected as of the close of business on
      the date on which the Company gives written notice to a holder of such
      1999 Subordinated Note that the Company shall convert all or part of such
      1999 Subordinated Note. At such time as such conversion has been effected,
      the rights of the holder of such 1999 Subordinated Note as provided
      hereunder with respect to the portion of the 1999 Subordinated Note to be
      converted will cease, and the Person or Persons in whose name or names any
      certificate or certificates for shares of Common Stock are to be issued
      upon such conversion will be deemed to have become the holder or holders
      of record of the shares of Common Stock represented thereby.

                (3) As soon as possible after a conversion has been effected and
      in no event later than twenty (20) business days thereafter, the Company
      will deliver to the converting holder:

                    (a) a certificate or certificates representing the number of
      shares of Common Stock issuable by reason of such conversion in such name
      or names and such denomination or denominations as the holder of the
      converted 1999 Subordinated Note has specified;

<PAGE>

                    (b) payment of all accrued and unpaid interest on such
      converted portion of the 1999 Subordinated Note;

                    (c) the amount payable under Subsection 6.a.(6) below with
      respect to such conversion; and

                    (d) if applicable, a replacement 1999 Subordinated Note
      representing any portion of the 1999 Subordinated Note which was not
      converted.

                (4) The issuance of certificates for shares of Common Stock upon
      conversion of a 1999 Subordinated Note will be made without charge to the
      holders of such 1999 Subordinated Note for any issuance tax in respect
      thereof or other cost incurred by the Company in connection with such
      conversion and the related issuance of shares of Common Stock. Upon
      conversion of all or any portion of a 1999 Subordinated Note, the Company
      will take all such actions as are necessary in order to insure that the
      Common Stock issued as a result of such conversion is validly issued,
      fully paid and nonassessable.

                (5) The Company will not close its books against the transfer of
      Common Stock issued or issuable upon conversion of the 1999 Subordinated
      Notes in any manner which interferes with the timely conversion of the
      1999 Subordinated Notes.

                (6) If any fractional interest in a share of Common Stock would,
      except for the provisions of this Subsection 6.a.(6), be deliverable upon
      any conversion of any 1999 Subordinated Note, the Company, in lieu of
      delivering the fractional share therefor, shall pay an amount to the
      holder thereof equal to the Fair Market Value of such fractional interest
      as of the date of conversion.

                (7) Any 1999 Subordinated Notes which are converted shall be
      canceled and will not be reissued or otherwise transferred.

                (8) The Company will take such corporate action as may be
      necessary from time to time so that at all times it will have authorized,
      and reserved out of its authorized but unissued Common Stock for the sole
      purpose of issuance upon conversion the 1999 Subordinated Notes, a
      sufficient number of shares of Common Stock to permit the conversion in
      full of the sum of the aggregate unpaid principal balances and accrued but
      unpaid interest due on all 1999 Subordinated Notes.

                (9) For purposes of this Section 6, "Fair Market Value" means
      the average of the last reported sales price of the Common Stock on the
      Nasdaq Stock Market or on any national or regional securities exchange on
      which the Common Stock is listed or admitted to unlisted trading
      privileges and on which the Common Stock is principally traded or quoted,
      as reported for each of the 10 consecutive trading days ending on the 10th
      trading date prior to any dividend payment date; or if there is no public
      market for the Common Stock of the Company, the Fair Market Value shall be
      calculated based on the price paid per share of Common Stock or the
      valuation of the Company in the Company's most recent equity financing
      transaction with a third party, or, if in the judgment of the Board of
      Directors of the Company, the fair market value is materially different
      from that reflected by such valuation, then the Fair Market Value shall be
      determined by the Board of Directors in good faith.

<PAGE>

              b. Adjustments to  1999 Subordinated Notes Conversion Price.

                (1) In order to prevent dilution of the interests of the holders
      of the 1999 Subordinated Notes as a result of the conversion right granted
      to the Company under this subsection 6, the 1999 Subordinated Note
      Conversion Price will be subject to adjustment from time to time pursuant
      to this Section 6.b. The term "1999 Subordinated Note Conversion Price"
      initially means $2.00, as subsequently adjusted as provided below.

                (2) If the Company issues or sells, or in accordance with
      Section 6.c. is deemed to have issued or sold, any shares of its Common
      Stock (except as set forth in Section 6.c.(9)) without consideration or
      for a consideration per share less than the 1999 Subordinated Note
      Conversion Price in effect immediately prior to the time of such issuance
      or sale, then upon such issuance or sale the 1999 Subordinated Note
      Conversion Price will be reduced to the conversion price determined by
      dividing (a) the sum of (1) the product derived by multiplying the 1999
      Subordinated Conversion Price in effect immediately prior to such issuance
      or sale times the number of fully-diluted shares of Common Stock
      outstanding immediately prior to such issuance or sale, and (2) the
      consideration, if any, received by the Company upon such issuance or sale,
      by (b) the number of shares of fully-diluted Common Stock outstanding
      immediately prior to such issuance or sale plus the number of shares of
      Common Stock issued or deemed to have been issued in such sale pursuant to
      this Section 6.

             c. Effect on 1999 Subordinated Note Conversion Prices of Certain
Events.

                (1) For purposes of determining the adjusted 1999 Subordinated
      Note Conversion Prices under Section 6.b., the following will be
      applicable:

                    (a) Issuance of Rights or Options. If the Company grants,
      issues or sells Options to acquire Common Stock or Convertible Securities
      and the price per share for which Common Stock is issuable upon the
      exercise of such Options or upon conversion or exchange of any Convertible
      Securities issuable upon the exercise of such Options is less than the
      1999 Subordinated Note Conversion Price in effect immediately prior to the
      time of the granting, issuance or sale of such Options, then the total
      maximum number of shares of Common Stock issuable upon the exercise of
      such Options or upon conversion or exchange of the total maximum amount of
      such Convertible Securities issuable upon the exercise of such Options
      shall be deemed to be outstanding and to have been issued and sold by the
      Company at the time of the granting of such Options for such price per
      share. For purposes of this Section, the "price per share for which Common
      Stock is issuable" shall be determined by dividing (A) the sum of (i) the
      amount, if any, received or receivable by the Company as consideration for
      the granting of such Options, plus (ii) the minimum aggregate amount of
      additional consideration payable to the Company upon exercise of all such
      Options, plus (iii) in the case of such Options which relate to
      Convertible Securities, the minimum aggregate amount of additional
      consideration, if any, payable to the Company upon the issuance or sale of
      such Convertible Securities and the conversion or exchange thereof, by (B)
      the total maximum number of shares of Common Stock issuable upon the
      exercise of such Options or upon the conversion or exchange of all such
      Convertible Securities issuable upon the exercise of such Options. No
      further adjustment of the 1999 Subordinated Note Conversion Price shall be
      made when Convertible Securities are actually issued upon the exercise of
      such Options or when Common Stock is actually issued upon the exercise of
      such Options or the conversion or exchange of such Convertible Securities.
<PAGE>

                    (b) Issuance of Convertible Securities. If the Company in
      any manner issues or sells any Convertible Securities and the price per
      share for which Common Stock is issuable upon such conversion or exchange
      thereof is less than the 1999 Subordinated Note Conversion Price in effect
      immediately prior to the time of such issue or sale, then the maximum
      number of shares of Common Stock issuable upon conversion or exchange of
      such Convertible Securities shall be deemed to be outstanding and to have
      been issued and sold by the Company at the time of the issuance or sale of
      such Convertible Securities for such price per share. For the purposes of
      this Section, the "price per share for which Common Stock" shall be
      determined by dividing (A) the sum of (i) the amount received or
      receivable by the Company as consideration for the issue or sale of such
      Convertible Securities, plus (ii) the minimum aggregate amount of
      additional consideration, if any, payable to the Company upon the
      conversion or exchange thereof, by (B) the total maximum number of shares
      of Common Stock issuable upon the conversion or exchange of all such
      Convertible Securities. No further adjustment of the 1999 Subordinated
      Note Conversion Price shall be made when Common Stock is actually issued
      upon the conversion or exchange of such Convertible Securities, and if any
      such issue or sale of such Convertible Securities is made upon exercise of
      any Options for which adjustments of the 1999 Subordinated Note Conversion
      Price had been or are to be made pursuant to other provisions of this
      Section 6, no further adjustment of the 1999 Subordinated Note Conversion
      Price shall be made by reason of such issue or sale.

                    (c) Change in Option Price or Conversion Rate. If the
      purchase price provided for in any Options, the additional consideration,
      if any, payable upon the issue, conversion or exchange of any Convertible
      Securities, or the rate at which any Convertible Securities are
      convertible into or exchangeable for Common Stock change at any time, the
      1999 Subordinated Note Conversion Price in effect at the time of such
      change shall be readjusted to the 1999 Subordinated Note Conversion Price
      which would have been in effect at such time had such Options or
      Convertible Securities originally provided for such changed purchase
      price, additional consideration or changed conversion rate, as the case
      may be, at the time initially granted, issued or sold.

                (2) For purposes of determining the adjusted 1999 Subordinated
      Note Conversion Price under Subsection 6.b.(2) and (3), the following will
      be applicable:
<PAGE>

                    (a) Calculation of Consideration Received. If any Common
      Stock, Options or Convertible Securities are issued or sold or deemed to
      have been issued or sold for cash, the consideration received therefor
      will be deemed to be the gross amount received by the Company therefor
      after deducting any discounts or commissions paid or incurred by the
      Company in connection with the issuance and sale. In case any Common
      Stock, Options or Convertible Securities are issued or sold for a
      consideration other than cash, the amount of the consideration other than
      cash received by the Company will be the Fair Market Value thereof as of
      the date of receipt. If any Common Stock, Options or Convertible
      Securities are issued in connection with any merger in which the Company
      is the surviving Company, the amount of consideration therefor will be
      deemed to be the Fair Market Value of such portion of the net assets and
      business of the non-surviving Company as is attributable to such Common
      Stock, Options or Convertible Securities, as the case may be.

                    (b) Integrated Transactions. In case any Options are issued
      in connection with the issue or sale of other securities of the Company,
      together comprising one integrated transaction in which no specific
      consideration is allocated to such Options by the parties thereto, the
      Options will be deemed to have been issued for a consideration of $0.01
      each.

                    (c) Treasury Shares. The number of shares of Common Stock
      outstanding at any given time shall not include shares owned or held by or
      for the account of the Company, and the disposition of any shares so owned
      or held will be considered an issue or sale of Common Stock.

                    (d) Record Date. If the Company takes a record of the
      holders of Common Stock for the purpose of entitling them (i) to receive a
      dividend or other distribution payable in Common Stock, Options or
      Convertible Securities or (ii) to subscribe for or purchase Common Stock,
      Options or Convertible Securities, then such record date will be deemed to
      be the date of the issue or sale of the shares of Common Stock deemed to
      have been issued or sold upon the declaration of such dividend or upon the
      making of such other distribution or the date of the granting of such
      right of subscription or purchase, as the case may be.

                (3) Subdivision or Combination of Common Stock. If the Company
      at any time subdivides one or more classes of its outstanding shares of
      Common Stock into a greater number of shares, the 1999 Subordinated Note
      Conversion Price in effect immediately prior to such subdivision will be
      proportionately reduced, and if the Company at any time combines (by
      combination, reverse stock split or otherwise) one or more classes of its
      outstanding shares of Common Stock into a smaller number of shares, the
      1999 Subordinated Note Conversion Price in effect immediately prior to
      such combination will be proportionately increased.

                (4) Stock Dividends. In the event of any stock dividend or other
      distribution payable in shares of Common Stock, or other securities or
      property of the Company, including securities of a third party, then in
      each such event the 1999 Subordinated Note Conversion Price shall be
      adjusted by multiplying the 1999 Subordinated Note Conversion Price then
      in effect by a fraction (i) the numerator of which is the total number of
      shares of Common Stock issued and outstanding immediately prior to the
      time of such issuance, and (ii) the denominator of which is the total
      number of shares of Common Stock issued and outstanding immediately prior
      to the time of such issuance plus the number of shares of Common Stock
      issuable in payment of such dividend or the number of shares of Common
      Stock which may be purchased at fair market value using the consideration
      equal to the aggregate Fair Market Value of the securities or other
      property of the Company to be distributed; provided, however, this
      adjustment shall exclude any such distributions to the extent a
      substantially similar distribution is made to the holders of the 1999
      Subordinated Notes.
<PAGE>

                (5) Distributions of Property. In the event that the Company
      makes a distribution of its property to the holders of Common Stock as a
      dividend in liquidation or partial liquidation or by way of return of
      capital or other than as a dividend payable out of funds legally available
      for dividends under the laws of the State of Delaware, the holders of 1999
      Subordinated Notes Preferred Stock shall, upon conversion thereof, be
      entitled to receive, in addition to the number of shares of Common Stock
      receivable thereupon, and without payment of any consideration therefor, a
      sum equal to the amount of such property as would have been payable to
      them as owners of that number of shares of Common Stock receivable upon
      such conversion, had they been the holders of record of such Common Stock
      on the record date for such distribution; and an appropriate provision
      therefor shall be made a part of any such distribution; provided, however,
      this adjustment shall exclude any such distributions to the extent a
      substantially similar distribution is made to the holders of the 1999
      Subordinated Notes.

                (6) Reorganization, Reclassification, Merger or Consolidation.
      If at any time, as a result of:

                    (i) a capital reorganization or reclassification (other than
            a subdivision, combination, dividend or distribution provided for in
            Subsections (3), (4) or (5) above); or

                    (ii) a merger or consolidation of the Company with another
            Company (whether or not the Company is the surviving Company), the
            Common Stock issuable upon the conversion of the 1999 Subordinated
            Notes shall be changed into or exchanged for the same or a different
            number of shares of any class or classes of stock of the Company or
            any other Company, or other securities convertible into such shares,
            then, as a part of such reorganization, reclassification, merger or
            consolidation, appropriate adjustments shall be made in the terms of
            the 1999 Subordinated Notes (or of any instruments or securities
            into which the 1999 Subordinated Notes are changed or converted or
            for which the 1999 Subordinated Notes are exchanged), so that:

                (x) the holders of shares of the 1999 Subordinated Notes or of
      such substitute securities shall thereafter be entitled to receive, upon
      conversion of the such 1999 Subordinated Notes or of such substitute
      securities, the substantially equivalent kind and amount of shares of
      stock, other securities, money and property which such holders would have
      received at the time of such capital reorganization, reclassification,
      merger, or consolidation, if the Company had elected to convert such 1999
      Subordinated Notes into Common Stock immediately prior to such capital
      reorganization, reclassification, merger, or consolidation, and

                (y) the 1999 Subordinated Notes or such substitute securities
      shall thereafter be adjusted on terms as nearly equivalent as may be
      practicable to the adjustments theretofore provided in this Section 6.c.

<PAGE>

         The provisions of this Subsection (6) shall similarly apply to
successive capital reorganizations, reclassifications, mergers, and
consolidations.

                (7) Certain Events. If any event occurs of the type contemplated
      by the provisions of Section 6.c. but not expressly provided for by such
      provisions, then the Board of Directors will make an appropriate
      adjustment in the 1999 Subordinated Note Conversion Price so as to protect
      the rights of the holders of the 1999 Subordinated Notes; provided,
      however, that, no such adjustment will increase the 1999 Subordinated Note
      Conversion Price as otherwise determined pursuant to Section 6.c. or
      decrease the number of shares of Common Stock issuable upon conversion of
      the 1999 Subordinated Notes.

                (8) Notwithstanding the foregoing, no adjustment to the 1999
      Subordinated Note Conversion Price shall be made for:

                    (a) issuances of Common Stock occurring prior to the date of
      this replacement Note;

                    (b) the issuance of warrants to officers, directors,
      shareholders or other investors in the Company, provided such issuance is
      approved by the Board of Directors;

                    (c) the issuance of shares of Common Stock into which the
      1999 Subordinated Notes are convertible;

                    (d) the issuance of shares of Common Stock upon exercise of
      all options and warrants outstanding as of the date of this replacement
      Note;

                    (e) the issuance of options to acquire shares of Common
      Stock under the Company's incentive stock option or similar plans(or the
      issuance of such Common Stock upon the exercise thereof), provided each
      such plan has been approved by the Board of Directors;

                    (f) the issuance of shares of Common Stock under the
      Company's stock purchase or similar plans, provided each such plan has
      been approved by the Board of Directors;

                    (g) the issuance of Common Stock or Options, warrants or
      rights to acquire Common Stock or the issuance of Common Stock upon the
      exercise thereof, in connection with (i) strategic transactions including
      acquisitions, joint ventures and similar arrangements, (ii) to vendors or
      suppliers or other business associates, (iii), in connection with debt
      financings or (iv) as compensation to service providers including without
      limitation, as brokers, finders and financial consultants, in connection
      with capital raising transactions.

<PAGE>

            d. Notices. As soon as practicable (and in any case not later than
      fifteen (15) days) upon any adjustment of the 1999 Subordinated Note
      Conversion Price, the Company will give written notice thereof to all
      holders of 1999 Subordinate Notes.

            e. Definitions.

                  "Convertible Securities" means securities convertible into or
         exchangeable for Common Stock.

                  "Options" means any grant, issue or sale by the Corporation of
         any right or option to subscribe for or to purchase Common Stock or any
         Convertible Securities.

         7. Warrant Coverage. Holder has received, on December 7, 1999, ten-year
warrants (the "Warrants) to purchase 800,000 shares of common stock of the
Company ("Common Stock"). The exercise price of the Warrants is $2.25 per share
of Common Stock of the Company. The Warrants are evidenced by Warrant
Certificates, issued in accordance with the terms of a Warrant Agreement.

         8. Subordination. The indebtedness evidenced by this Note shall at all
times be wholly subordinate and junior in right of payment to all obligations of
the Company under or in connection with the Credit Agreement of even date
herewith ("Superior Debt") among the Company as guarantor, the borrowers CECO
Group Inc., CECO Filters, Inc., Air Purator Corporation, New Bush Co., Inc.,
U.S. Facilities Management, Inc., The Kirk & Blum Manufacturing Company, and
kbd/Technic, Inc., and the lenders PNC Bank, National Association and various
other financial institutions, upon the terms and conditions contained in the
Subordination Agreement between Green Diamond Oil Corp., Harvey Sandler, ICS
Trustee Services, Ltd., and PNC Bank, National Association and various other
financial institutions of even date herewith (the "Subordination Agreement").

         9. Repayment of Notes. In the event the Company completes an equity
financing or offering or a series of equity financing or offerings for a total
consideration in excess of $10,000,000, then twenty-five percent (25%) of all
such consideration in excess of $10,000,000 shall be used immediately, upon
receipt by the Company, to pre-pay the 1999 Subordinated Notes, provided such
prepayment shall be made proportionately among the 1999 Subordinated Notes until
the 1999 Subordinated Notes are paid in full.

         10. Covenants of the Company. The Company covenants and agrees that it
shall not, without the prior written approval of the Holders of a majority of
the aggregate principal amount outstanding of the 1999 Subordinated Notes
("Majority Holders"):
<PAGE>

                    a. Obtain or incur any indebtedness or other monetary
      obligations that are senior to or on parity with the Notes, other than the
      Superior Debt.

                    b. Allow, suffer or cause to exist any lien, claim, security
      interest or encumbrance on the Company's property or assets, other than
      with respect to the Superior Debt and purchase money indebtedness incurred
      in the ordinary course of business.

                    c. Enter into any arrangement or agreement involving the
      merger or consolidation of the Company.

                    d. Use the proceeds from the sale of the 1999 Subordinated
      Notes other than in the ordinary course of its business for general
      corporate purposes including lending monies to any of its subsidiaries.
      The Company also covenants and agrees that it shall operate its business
      in the ordinary course.

         11. Events of Default.

                    a. Occurrences of Events of Default. Each of the following
      events shall constitute an "Event of Default" for purposes of this Note:

                       (1) if the Company fails to pay any amount payable, under
            this Note when due;

                       (2) if the Company breaches any of its representations,
            warranties or covenants set forth in this Note or the Warrant
            Agreement;

                       (3) the commencement of an involuntary case against the
            Company or its subsidiary or any of its subsidiaries under any
            applicable bankruptcy, insolvency or other similar law now or
            hereafter in effect, or the appointing of a receiver, liquidator,
            assignee, custodian, trustee or similar official of the Company or
            for any substantial part of the Company or one of its subsidiary's
            property, or ordering the winding-up or liquidation of the Company
            or one of its subsidiary's affairs;

                       (4) if the Company or any of its subsidiaries shall
            commence a voluntary case under any applicable bankruptcy,
            insolvency or other similar law now or hereafter in effect, or shall
            consent to the entry of an order for relief in an involuntary case
            under any such law, or shall consent to the appointment of or taking
            possession by a receiver, liquidator, assignee, trustee, custodian
            or similar official of the Company or its subsidiary or for any
            substantial part of the Company or one of its subsidiary's property,
            or shall make any general assignment for the benefit of creditors,
            or shall take any corporate action in furtherance of any of the
            foregoing; or

<PAGE>

                       (5) if the Company's business shall fail, as determined
            in good faith by the Majority Holders and evidenced by the Company's
            inability to pay its ongoing debts as such debts become due.

            b. Acceleration Upon Event of Default. If any Event of Default shall
      have occurred and be continuing, for any reason whatsoever (and whether
      such occurrence shall be voluntary or involuntary or come about or be
      effected by operation of law or otherwise), the unpaid principal amount
      of, and the accrued interest on, the Notes shall automatically become
      immediately due and payable, without presentment, demand, protest or other
      requirements of any kind, all of which are hereby expressly waived by the
      Company.

         12. Investment Representations of the Holder. With respect to the
purchase of this Note, the Common Stock issuable upon the exercise of the
Warrants (collectively, the "Securities"), the Holder hereby represents and
warrants to the Company as follows:

            a. Experience. The Holder has substantial experience in evaluating
      and investing in private placement transactions of securities in companies
      similar to the Company so that it is capable of evaluating the merits and
      risks of its investment in the Company and has the capacity to protect its
      own interests.

            b. Investment. The Holder is acquiring the Securities for investment
      for its own account, not as a nominee or agent, and not with the view to,
      or for resale in connection with, any distribution thereof. The Holder
      understands that the Securities have not been, and will not be, registered
      under the Securities Act of 1933, as amended ("Securities Act"), by reason
      of a specific exemption from the registration provisions of the Securities
      Act, the availability of which depends upon, among other things, the bona
      fide nature of the investment intent and the accuracy of the Holder's
      representations as expressed herein. The holder is an "accredited
      investor" within the meaning of Regulation D, Section 501(a), promulgated
      by the Securities and Exchange Commission.

            c. Rule 144. The Holder acknowledges that the Securities must be
      held indefinitely unless subsequently registered under the Securities Act,
      or unless an exemption from such registration is available. The Holder
      understands that at this time the Company is not under any obligation to
      register any of the Securities. The Holder is aware of the provisions of
      Rule 144 promulgated under the Securities Act that permit limited resale
      of securities purchased in a private placement subject to satisfaction of
      certain conditions.

            d. No Public Market. The Holder understands that no public market
      now exists for any of the Securities issued by the Company and that the
      Company has made no assurances that a public market will ever exist for
      the Securities.

<PAGE>

            e. Access to Data. The Holder has had an opportunity to discuss the
      Company's business, management and financial affairs with the Company's
      management and has also had an opportunity to ask questions of the
      Company's officers, which questions were answered to its satisfaction.

        13. Miscellaneous.

            a. Invalidity of Any Provision. If any provision or part of any
      provision of this Note shall for any reason be held invalid, illegal or
      unenforceable in any respect, such invalidity, illegality or
      unenforceability shall not affect any other provisions of this Note and
      this Note shall be construed as if such invalid, illegal or unenforceable
      provisions or part hereof had never been contained herein, but only to the
      extent of its invalidity, illegality or unenforceability.

            b. Governing Law. The Note shall be governed in all respects by the
      laws of the State of New York, excluding its conflict of laws.

            c. Notices. Any notice or other communication required or permitted
      hereunder shall be in writing and shall be deemed to have been duly given
      (i) on the date of delivery if delivered personally, (ii) one (1) business
      day after transmission by facsimile transmission with a written
      confirmation copy sent by first class mail, or (iii) five (5) days after
      mailing if mailed by first class mail, to the following addresses:

                  If to the Company:        CECO Environmental Corp.
                                            505 University Avenue, Suite 1400
                                            Toronto, Ontario M5G 1X3
                                            CANADA
                                            Attention: Phillip DeZwirek

            And if to the Holder, to the address or facsimile number of Holder
      as set forth on the Company's records, or such other address as the Holder
      has provided to the Company by notice duly given.

            d. Notice of a Sale Transaction. The Company shall give all Holders
      of Notes notice of the Closing of a Sale Transaction at least thirty (30)
      days prior to such Closing.

            e. Collection. If the indebtedness represented by the Note or any
      part thereof is collected at law or in equity or in bankruptcy,
      receivership or other judicial proceedings or if the Note is placed in the
      hands of attorneys for collection after the occurrence of an Event of
      Default, the Company agrees to pay, in addition to the outstanding
      principal and accrued interest payable hereon, reasonable attorneys' fees
      and costs incurred by the Holder, or on behalf of the Holder by a
      representative of the Holder.

<PAGE>

            f. Successors and Assigns. The rights and obligations of the Company
      and the Holder shall be binding upon and benefit the successors, assigns,
      heirs, administrators and transferees of the parties.

            g. Waivers. The Company and any endorsers, sureties, guarantors, and
      all others who are, or may become liable for the payment hereof severally:
      (a) waive presentment for payment, demand, notice of demand, notice of
      nonpayment or dishonor, protest and notice of protest of this Note, and
      all other notices in connection with the delivery, acceptance,
      performance, default, or enforcement of the payment of this Note, (b)
      consent to all extensions of time, renewals, postponements of time of
      payment of this Note or other modifications hereof from time to time prior
      to or after the maturity date hereof, whether by acceleration or in due
      course, without notice, consent or consideration to any of the foregoing,
      (c) agree to any substitution, exchange, addition, or release of any of
      the security for the indebtedness evidenced by this Note or the addition
      or release of any party or person primarily or secondarily liable hereon,
      (d) agree that Holder shall not be required first to institute any suit,
      or to exhaust its remedies against the Company or any other person or
      party to become liable hereunder or against the security in order to
      enforce the payment of this Note and (e) agree that, notwithstanding the
      occurrence of any of the foregoing (except by the express written release
      by Holder of any such person), the Company shall be and remain, directly
      and primarily liable for all sums due under this Note.

            h. Time. Time is of the essence in this Note.

            i. Captions. The captions of sections of this Note are for
      convenient reference only, and shall not affect the construction or
      interpretation of any of the terms and provisions set forth in this Note.

            j. Number and Gender. Whenever used in this Note, the singular
      number shall include the plural, and the masculine shall include the
      feminine and the neuter, and vice versa.

            k. Remedies. All remedies of the Holder shall be cumulative and
      concurrent and may be pursued singly, successively, or together at the
      sole discretion of the Holder and may be exercised as often as occasion
      therefor shall arise. No act of omission or commission of the Holder,
      including specifically any failure to exercise any right, remedy or
      recourse shall be effective unless it is set forth in a written document
      executed by the Holder and then only to the extent specifically recited
      therein. A waiver or release with reference to one event shall not be
      construed as continuing as a bar to or as a waiver or release of any
      subsequent right, remedy, or recourse as to any subsequent event.

            l. No Waiver by Holder. The acceptance by Holder of any payment
      under this Note which is less than the amount then due or the acceptance
      of any amount after the due date thereof, shall not be deemed a waiver of
      any right or remedy available to Holder nor nullify the prior exercise of
      any such right or remedy by Holder. None of the terms or provisions of
      this Promissory Note may be waived, altered, modified or amended except by
      a written document executed by Holder and then only to the extent
      specifically recited therein. No course of dealing or conduct shall be
      effective waive, alter, modify or amend any of the terms or provisions
      hereof. The failure or delay to exercise any right or remedy available to
      Holder shall not constitute a waiver of the right of the Holder to
      exercise the same or any other right or remedy available to Holder at that
      time or at any subsequent time.

<PAGE>

            m. Submission to Jurisdiction. BORROWER, AND ANY ENDORSERS,
      SURETIES, GUARANTORS AND ALL OTHERS WHO ARE, OR WHO MAY BECOME, LIABLE FOR
      THE PAYMENT HEREOF SEVERALLY, IRREVOCABLY AND UNCONDITIONALLY (A) AGREE
      THAT ANY SUIT, ACTION, OR OTHER LEGAL PROCEEDING ARISING OUT OF OR
      RELATING TO THIS NOTE OR ANY OTHER AGREEMENT, DOCUMENT OR INSTRUMENT
      DELIVERED PURSUANT TO, OR IN CONNECTION WITH THIS NOTE SHALL BE BROUGHT
      AND MAINTAINED IN THE COURTS IN AND FOR NEW YORK COUNTY, NEW YORK, OR IN
      THE UNITED STATES DISTRICT COURT FOR THE SOUTHERN DISTRICT OF NEW YORK;
      (B) CONSENT TO THE JURISDICTION OF EACH SUCH COURT IN ANY SUCH SUIT,
      ACTION OR PROCEEDING; AND (C) WAIVE ANY OBJECTION WHICH IT OR THEY MAY
      HAVE TO THE LAYING OF VENUE OF ANY SUCH SUIT, ACTION, OR PROCEEDING IN ANY
      OF SUCH COURTS.

            n. Waiver of Trial by Jury. HOLDER AND BORROWER HEREBY KNOWINGLY,
      IRREVOCABLY, VOLUNTARILY AND INTENTIONALLY WAIVE ANY RIGHT EITHER MAY HAVE
      TO A TRIAL BY JURY IN RESPECT OF ANY ACTION, PROCEEDING OR COUNTERCLAIM
      BASED ON THIS NOTE, OR ARISING OUT OF, UNDER OR IN CONNECTION WITH THIS
      NOTE OR ANY OTHER DOCUMENT EXECUTED IN CONNECTION THEREWITH, OR ANY COURSE
      OF CONDUCT, COURSE OF DEALING, STATEMENTS (WHETHER VERBAL OR WRITTEN) OR
      ACTIONS OF ANY PARTY HERETO. THIS PROVISION IS A MATERIAL INDUCEMENT FOR
      HOLDER TO MAKE THE LOAN EVIDENCED BY THIS NOTE.

                                           CECO ENVIRONMENTAL CORP.

                                           By: /s/ Phillip DeZwirek
                                               ------------------------------
                                               Phillip DeZwirek, President

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