RAE Systems Extends Photoionization Detection Leadership with Award of U.S. Patent 6,734,435

Pioneering development in self-cleaning, continuous operation PID lamps extends companys leadership in photoionization detection technologies

SUNNYVALE, Calif. June 7, 2004 RAE Systems Inc. (AMEX: RAE), a leading global developer and manufacturer of rapidly-deployable, multi-sensor chemical and radiation detection monitors and networks for homeland security and industrial applications, today announced that the company has been awarded U.S. patent 6,734,435 for pioneering photoionization detection (PID) improvements based on the work of Hong T. Sun, Ph.D. and Peter C. Hsi, Ph.D. PIDs are used to detect levels of toxic volatile organic compounds (VOCs). VOCs are the by-product of oil refining, plastics manufacturing and chemical processing.

PIDs work by using Ultraviolet light to ionize the gas. Users of conventional PIDs must regularly clean a layer of contamination that builds on the PIDs optical window. This PID development, pioneered by RAE Systems, enables continuous operation and self-cleaning of PID lamps, and requires the least calibration of any PID portable or fixed system products on the market. In real-world use, the field environment is hazardous and chaotic, and first responders, industrial safety and military users must count on their equipment to help them protect lives and assets. With the new RAE Systems PID enhancements, gas detection instrument users now have the peace of mind that their monitors are providing the most accurate data for the longest period of time without any manual maintenance.

Photoionization detection is the most powerful method to detect the hundreds of volatile organic chemicals that present a daily threat in hazardous situations, and we are proud of Dr. Sun, Dr. Hsi and their team as they continue to innovate market leading technologies that protect human lives, said Robert I. Chen, CEO of RAE Systems. With the award of this patent, RAE Systems solidifies its position as the leader in PID detection technologies with the markets most rugged, stable monitors that are the de facto choice when lives are on the line.

This technology will be available in the recently announced EntryRAE, a five gas detector for confined space entry that includes the patented VOC sensor as well as sensors for breathable oxygen level (O2), carbon monoxide (CO), hydrogen sulfide (H2S) and lower explosive limit (LEL).

About RAE Systems
RAE Systems is a leading global developer and manufacturer of rapidly-deployable, multi-sensor chemical detection monitors and networks for homeland security and industrial applications. In addition, RAE Systems offers a full line of portable single-sensor chemical and radiation detection products. RAE Systems products enable the military and first responders such as firefighters, law enforcement and other emergency management personnel to detect and provide early warning of weapons of mass destruction and other hazardous materials. Industrial applications include the detection of toxic industrial chemicals, volatile organic compounds and petrochemicals. RAE Systems products are used by many U.S. government agencies, including the Department of Homeland Security, the Department of Justice, and the Department of State, as well as all branches of the U.S. military, and by numerous city and state agencies. Our end users also include many of the worlds leading corporations in the airline, automotive, computer and oil industries. Our products are used in civilian and government atmospheric monitoring programs in over 50 countries. For more information about RAE Systems, please visit www.RAESystems.com