Arch Chemicals Announces Global Price Increases for Omadine(R), Omacide(R) and Triadine(R) Biocides.

NORWALK, Conn. -- Citing continued increases in the costs of key raw materials, transportation and packaging, Arch Chemicals, Inc. (NYSE:ARJ) announces the following global list- and off-list price increases for their Omadine(R), Omacide(R) and Triadine(R) product families effective December 1, 2005, or as contracts allow.

Prices for Omadine(R), pyrithione-based products (including for personal care applications, such as antidandruff shampoos) will increase by 7.5 percent.

Prices for Omacide(R), IPBC-based products will increase as follows: Omacide(R) IPBC 20 industrial fungicides by 53-cents per pound; Omacide(R) IPBC 30 industrial fungicides by 73-cents per pound; Omacide(R) IPBC 40 industrial fungicides by 83-cents per pound; and Omacide(R) IPBC 100 industrial fungicides by $1.78 per pound.

Prices for Triadine(R) biocides will increase as follows: Triadine(R) 3 and Triadine(R) 174 by 18-cents per pound; and Triadine(R) 10 and Triadine(R) 20 by 28-cents per pound.

For more information on Arch's biocides business, please visit www.archbiocides.com. Those interested in Arch's personal care ingredients should visit www.archpersonalcare.com.

Headquartered in Norwalk, Connecticut, Arch Chemicals, Inc. is a global specialty chemicals company with approximately $1.3 billion in annual sales. Arch and its subsidiaries have market leadership positions in the Treatment and Performance Products segments, where they serve leading customers with forward-looking solutions to meet their chemical needs. Together with its subsidiaries, Arch has approximately 3,000 employees and manufacturing and customer-support facilities in North and South America, Europe, Asia and Africa.