By Liu Shengnan

Local authorities assured Wednesday that the amount of iodine-131 detected in the air from Japan's radiation leaks is harmless to public health despite levels having risen eightfold in the past week.

The Shanghai Environmental Protection Bureau said that although the levels are much higher than those measured on March 28, they are still far below the national safety limit, according to Chen Wei, chief of the bureau's radiation department.

"There is no need to be concerned or set off false alarms," he told the Global Times Wednesday. "Radiation levels in the air also fluctuate depending on a number of factors such as atmospheric diffusion."

He said that without further investigation of the situation it would be unfair to conclude that the reading proves the city's iodine-131 levels have, in fact, increased in the past several days, adding that officials are continuing to monitor and assess conditions.

Chen emphasized that the levels were much lower than those experienced in Japan, where hundreds of Japanese residents living near the Fukushima plant were evacuated from the area – a protocol that would also be followed in Shanghai if needed, though highly unlikely, he said.

The State Oceanic Administration's East China Sea branch chimed in Wednesday, too, saying that monitoring operations remain in place.

It said that no traces of radioactivity have been discovered in the waters since the earthquake and subsequent tsunami in Japan hit, causing the country's radiation problems.