Arch Chemicals Purchases Remaining 50 Percent of Joint-Venture Aquachlor HTH Swimming Pool Sanitizer Business in South Africa.

Business Editors

NORWALK, Conn.--(BUSINESS WIRE)--Aug. 7, 2003

Arch Chemicals, Inc. (NYSE: ARJ) has completed the purchase of the remaining 50 percent of Aquachlor (Proprietary) Limited in South Africa from its joint-venture partner Sentrachem Limited, a subsidiary of The Dow Chemical Company. The plant produces calcium hypochlorite, a dry sanitizer which it markets under the HTH(R) brand for use in residential and commercial swimming pools. The sanitizer is also used to purify drinking water and to treat water used in industrial applications such as South African gold and platinum mines.

Arch paid approximately $6 million in the transaction, which has received approval from South African government authorities. Located in Kempton Park, South Africa, the Aquachlor plant is the sole producer of calcium hypochlorite in Africa and has an annual production capacity of 40 million pounds. Annual sales of this entity for the year ended December 31, 2002 were approximately $20 million. The business is the leading supplier to the sizeable South African swimming pool market.

"This transaction gives us the flexibility to expand our product offerings and to capitalize on major water-treatment growth opportunities in both Africa and Asia," said Arch Chemicals' Chairman, President and CEO Michael E. Campbell. "We plan to significantly grow our business of providing sanitizers to address the need for potable water throughout Africa and to capitalize on both residential and industrial water-treatment applications in Asia."

David L. van Den Berg is serving as Business Director of the business, which is being renamed Arch Water Treatment South Africa. The manufacturing plant employs approximately 100 employees, and Arch has an additional 40 full-time sales and marketing employees located at other offices throughout South Africa.

Headquartered in Smyrna, Georgia, Arch's HTH Water Products business is the world's largest producer of calcium hypochlorite water sanitizers, which are used in everything from swimming pools to food production plants and municipal drinking water systems. Arch's sanitizers are also being used in villages in Africa and other regions to fight water-borne diseases, which are still responsible for the deaths of millions of people every year, particularly in undeveloped countries.

Arch Chemicals, Inc. (NYSE: ARJ), which is headquartered in Norwalk, Connecticut, is a global specialty chemicals company with approximately $1 billion in annual sales. Together with its subsidiaries, Arch has 3,000 employees worldwide and manufacturing facilities in North America, South America, Europe, Asia and Africa. Arch and its subsidiaries have leadership positions in four business segments -- Microelectronic Materials, Treatment Products, Performance Products and Other Specialty Products -- where they serve leading customers in these markets with forward-looking solutions to their chemical needs. For more information, visit Arch's Web site at www.archchemicals.com.