SC State scientist reports decrease in radiation levels

Thursday, May 19, 2011

The trace amount of  radioiodine levels detected in the atmosphere in Orangeburg, S.C.,  have dwindled 100 times since they were first detected on March 15 by SC State University’s Dr. Zheng Chang, visiting associate professor of radiochemistry and director of the Applied Radiation Sciences Laboratory.

Air samples collected March 18-21 by Chang at SC State revealed the presence of iodine-131 and radiocesium from Japan's Fukushima Daiichi Power Plant accident. Natural dispersion of particles in the air and descent of these particles to the ground contributed to the decrease, according to Chang.  The radiochemist further explained that radioactive iodine naturally decreases by half every eight days, and thus within three months, the iodine particles will have decayed and transformed into harmless stable atoms. 

In addition to detecting the presence of radioactive materials, Chang was able to measure its concentration to estimate the maximum possible dose exposure a person could be exposed to in the worst scenario.

“This process is crucial,” he says. “We need to know exactly how much radiation is in the atmosphere so that we can evaluate possible health and safety risks. By doing this, we can also serve as a regional staging area in the event that a nuclear situation occurs in the state.”

Chang’s measurements show that even at its peak, iodine levels were lower than the level of natural radiation.  As a result, he said, no health risk was posed to the Orangeburg community.  

“On the day with the highest levels of iodine-131 and radiocesium, one Orangeburg resident was only exposed to an extra 1/500 radiation dose of what he or she is exposed to in an average day from the sun, soil, ground water, food and medical machinery,” said Chang. “Radiation emitted from a simple dental x-ray for example, is 150 times more than the radioisotopes received from Japan.”

In the worst scenario, Chang added, the possible maximum dose a person in Orangeburg exposed to the Fukushima nuclear fallout is 1/140 times of what he or she is exposed to in a single flight from New York to Tokyo.

The U.S. Regulatory Commission has set limits for radioiodine to which the public could be exposed. The limit for iodine-131 in the air is close to 700 times more than the levels detected in Orangeburg.

The professor and several students are monitoring the atmosphere from an air sampler that he and his team installed on the rooftop of Sojourner Truth Residential Hall on S.C. State's campus. Standing an approximate height of 150 feet, the residential hall is considered the tallest building in Orangeburg, S.C. 

The atmospheric monitoring is part of an environmental radiochemistry study that Chang is conducting at the university.  The efforts are funded through a $450,000 grant awarded to Chang and Dr. Kenneth Lewis, dean of the College of Science, Mathematics, Engineering and Technology. The project also complements Chang’s SC State University 1890 Research & Extension study,  which he and his students are monitoring groundwater and soil in the state’s Midlands and Low Country regions for radiation levels.

Additionally, Chang’s research is inclusive of the various academic, research and outreach programs and activities that comprise the curricula for the radiochemistry, nuclear engineering and health physics majors, who are matriculating through the university’s accredited nuclear engineering program, the only such undergraduate program in the state.

For more information on SC State University’s environmental radiochemistry research, contact Dr. Zheng Chang at (803) 536-7924 or