VICTORIA, BRITISH COLUMBIA--(Marketwire - May 4, 2012) - E. S. I. Environmental Sensors Inc. ("ESI" or the "Company") (TSX VENTURE:ESV) is pleased to announce the closing of a "Shares for Debt" transaction previously announced on April 5, 2012. The Company has now issued 49,795,499 common shares at a deemed price per common share of $0.05 for settlement of $2,489,775 in debt. The debt settlements consist mainly of convertible debentures and accumulated interest.

The shares for debt transaction included the conversion of principal and all accrued interest previously owing to holders of matured convertible debentures for a total value of $2,463,458.45 into 49,269,169 common shares. Included in this amount, Avis Financial Corporation ("Avis Financial"), a controlling shareholder of the Company, received 34,106,080 common shares for the repayment of convertible debentures and accumulated interest. With the closing of this transaction, Avis Financial now owns 54.13% of the issued and outstanding common shares of the Company (Avis Financial previously held 43.7% of the issued and outstanding common shares of the Company).

In addition to the common shares issued in settlement of the convertible debentures, 526,330 common shares were issued to a former employee of the Company as part of a settlement agreement.

The Shares for Debt Transaction has been accepted by the TSX Venture Exchange.

About ESI

ESI is a leading manufacturer of patented and proprietary solutions for environments where understanding the presence, movement, and/or amount of water are important. Major market sectors include: agriculture, golf and turf, scientific research, civil engineering, mining, environmental monitoring and crude oil production. ESI solutions have been successfully introduced into more than 40 countries to enable customers to optimize their operations by monitoring the presence and movement of water, managing irrigation systems, and monitoring the integrity of landfill covers. In addition, ESI's Flo·Point™ instrument has been deployed in the oil industry to measure the volumetric presence of water pumped during crude oil extraction for characterization and optimization of the process. ESI differentiates itself by translating the best technology and science available into practical, easy to use solutions. Irrigation managers, reservoir engineers, and scientists have adopted ESI's products for their accuracy, ease of use, repeatability, and ability to operate in challenging environments. ESI is publicly traded on the TSX Venture Exchange under the symbol "ESV". Further information about ESI may be obtained through the Company's website at [ www.esica.com ].

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