Holding(s) in Company

TR-1: NOTIFICATION OF MAJOR INTEREST IN SHARESi

1. Identity of the issuer or the underlying issuerof existing shares to which voting rights areattached: ii

PORVAIR PLC

2 Reason for the notification (please tick the appropriate box or boxes):

An acquisition or disposal of voting rights

YES

An acquisition or disposal of qualifying financial instruments which may result in the acquisition of shares already issued to which voting rights are attached

NO

An acquisition or disposal of instruments with similar economic effect to qualifying financial instruments

NO

An event changing the breakdown of voting rights

NO

Other (please specify):

N/A

3. Full name of person(s) subject to thenotification obligation: iii

IMPAX ASSET MANAGEMENT LIMITED

4. Full name of shareholder(s)  (if different from 3.):iv

IMPAX ENVIRONMENTAL MARKETS PLC,

IMPAX ENVIRONMENTAL MARKETS IRELAND,

PARVEST ENVIRONMENTAL OPPORTUNITIEIS FUND

THE ENVIRONMENT AGENCY FUND

5. Date of the transaction and date onwhich the threshold is crossed orreached: v

28th November 2012

6. Date on which issuer notified:

29th November 2012

7. Threshold(s) that is/are crossed orreached: vi, vii

9% 8% 7%

8. Notified details:

A: Voting rights attached to shares viii, ix

Class/type ofshares

if possible usingthe ISIN CODE

Situation previousto the triggeringtransaction

Resulting situation after the triggering transaction

NumberofShares

NumberofVotingRights

Numberof shares

Number of votingrights

% of voting rights x

Direct

Direct xi

Indirect xii

Direct

Indirect

GB0006963689

3,898,621

9.1490%

2,900,801

N/A

2,900,801

N/A

6.8074%

B: Qualifying Financial Instruments

Resulting situation after the triggering transaction

Type of financialinstrument

Expirationdate xiii

Exercise/Conversion Period xiv

Number of votingrights that may beacquired if theinstrument isexercised/ converted.

% of votingrights

NIL

C: Financial Instruments with similar economic effect to Qualifying Financial Instruments xv, xvi

Resulting situation after the triggering transaction

Type of financialinstrument

Exercise price

Expiration date xvii

Exercise/Conversion period xviii

Number of voting rights instrument refers to

% of voting rights xix, xx

NIL

Nominal

Delta

Total (A+B+C)

Number of voting rights

Percentage of voting rights

2,900,801

6.8074%

9. Chain of controlled undertakings through which the voting rights and/or thefinancial instruments are effectively held, if applicable: xxi

IMPAX ENVIRONMENTAL MARKETS PLC (1,653,970 SHARES 3.8814%),

IMPAX ENVIRONMENTAL MARKETS IRELAND (452,260 SHARES 1.0613%),

PARVEST ENVIRONMENTAL OPPORTUNITIES FUND (526,621 SHARES 0.0124%),

THE ENVIRONMENT AGENCY FUND (267,950 SHARES 0.6288%)

Proxy Voting:

10. Name of the proxy holder:

N/A

11. Number of voting rights proxy holder will ceaseto hold:

N/A

12. Date on which proxy holder will cease to holdvoting rights:

N/A

13. Additional information:

Based on 42,612,572 issued ordinary shares

14. Contact name:

Chris Tyler

15. Contact telephone number:

01553 765 500