By Li Hongmei

Now, with hazardous smog threat and lingering public fear, Japan is offering tech know-how to a polluted China.

Recently, as part of a mission to improve bilateral relations and avert further aggression over disputed islands, a new accord was signed that promises to increase sharing of pollution-control technology with China.

It seems Japan is a perfect partner for China in its bid to clean up. After all, Japan had the same track record of environmental disasters in the 1960s and 1970s, explains Yoshihito Iwama, the environmental bureau director of the Japan Business Federation, known as Keidanren in Japan. Its plight was solved by creating new laws and technologies to deal with pollution.

High on China's agenda now is to prevent the disbursement of so-called PM2.5 air pollution -- hazardous airborne particles only 2.5 thousandths of a millimeter across -- that can penetrate deep into human tissue to cause serious health problems.

It is said Japan has the technology to help trace the origins of PM2.5 and to predict its disbursement, according to Japanese officials.

While both governments iron out the details of the accord, private firms such as Sharp and Panasonic (PC) have been reaping an unexpected windfall selling electronics in China that help purify the air. Sales of Sharp's air purifiers -- which China certifies "remove 99% of PM2.5" -- tripled in January compared with the same month of 2012. "Awareness of health and environment among consumers in China has increased in the past few years, so our air purifiers are selling extremely well there," says a Sharp spokeswoman.

Despite an informal boycott of Japanese goods in China as a result of Japan's "purchase" of the Diaoyu Islands, Japanese officials insist that trade relations are still excellent between the two countries. Japan has extensive business interests in China and will benefit hugely in the supply chain with China getting serious about detoxing its landscape.