During a briefing on East China's choking air pollution hosted by the Japanese embassy in Beijing, a Japanese man in his 50s raised his hand and asked, seriously: "So, should I grow out my nose hair or not?"

For Yuta Okazaki, the first secretary at the embassy who was briefing the Japanese audience, it was the most interesting and embarrassing question he had ever heard. Okazaki has worked on legal cases surrounding environmental pollution in Japan. But when it came to the question of growing one's nose hair to filter out air particles into the lungs, he turned to a medical expert for help.

The tiny particles of pollution the elderly man was worried about are known as PM2.5. They are less than 2.5 micrometers in size, or about 1/30th the width of a human hair, and can penetrate deep into the lungs. The medical expert replied that nose hairs may sweep some of the particles up his nose, but cutting them or not was a personal lifestyle choice.

Since January, thick and choking smog has regularly blanketed Beijing and other cities in China. Japanese media and officials suggest the pollution is making its way across the East China Sea to Japan, further complicating the already-strained relationship between the two countries.

According to a report of Singapore-based news portal zaobao.com earlier last month, Japan's Environment Minister Nobuteru Ishihara said in a speech that Japan is willing to provide free equipment and technical support to help China tackle the pollution problem, but the Chinese government has shown little interest in working with Japan.

In response, Sun Xuefeng, director for Asian affairs of China's environmental bureau, told the Global Times that the media report is a misunderstanding as earlier this month government officials and scholars from both sides gathered in Beijing to discuss bilateral cooperation to fight against air pollution.

"We hope Japanese can support us with its advanced technology and experience," Sun said. "And hopefully it will be in the form of non-reimbursable assistance."

Hideaki Koyanagi, director of the Institute for Global Environmental Strategies (IGES)'s Beijing office, sees the air pollution issue as an opportunity to improve Sino-Japanese relations.

"Pollution knows no borders," Koyanagi told the Global Times. "What the Japanese people don't understand is if we help to improve the air quality in China, it will eventually benefit Japan."

Being choked out

Since January, the PM2.5 level in Beijing has consistently topped 500 micrograms per cubic meter, far exceeding the hazardous level set by the World Health Organization. The pollution has become so bad that some joke that they can smell China's GDP in the air.

Pictures of Beijing's choking smog have been prominently displayed on Japanese television and magazines, and have had many Japanese residents worried as the country's daily standard for PM2.5 is 35 micrograms per cubic meter.

The March 21 issue of the Shukan Bunshun newsmagazine described China as a "pollution superpower" and suggested that poor air quality was to blame for health problems in China.

China's air pollution is high on the political agenda in Japan. The governor of Osaka Prefecture, Matsui Ichiro, openly criticized China saying the Chinese government should protect its citizens' health at the same time as developing its economy, according to the Kyodo news agency.

As fear of the unknown grows, 16 briefings have been hosted in the consulate-generals of Japan and Japanese schools across China in the past two months.

Some Japanese companies have asked the embassy to set up a safety standard, saying if PM2.5 readings exceed this level, they will close their offices in China and send their Japanese employees home, said Okazaki.

Earlier in March, officials in Kumamoto, on Kyushu Island, issued the country's first official health warning over smog partly drifting in from China, advising residents to stay indoors. The Environment Ministry has announced a plan to scale up the number of monitoring stations from 645 to 1,300.

 "I feel sorry that Japanese people are only concerned about their own health, not for that of the Chinese who are living in Beijing's polluted air," said Koyanagi, who has been living in China for 13 years.

Koyanagi wrote an op-ed piece for the Kyodo News, outlying China's efforts to control air pollution such as shutting down polluting and unsafe factories and promoting clean energies.

"Blaming China can't solve the air pollution problem," Koyanagi said. "It is very important for Japan to use its experience to help China with its policymaking and understand that helping China is helping itself."

Fighting side by side

On April 18, some 100 government officials, scholars and businesspeople gathered together in Beijing to discuss bilateral cooperation over air pollution control. The seminar was jointly hosted by the Sino-Japan Friendship Center for Environmental Protection, IGES, and Japan International Cooperation Agency (JICA).

Speaking at the opening ceremony, Song Tiedong, director of the Sino-Japan center, expressed gratitude for Japan's cooperation.

"The root cause of air pollution is fossil-fuel dependence and an unsustainable development pattern," Song said, "Many developed countries like Japan experienced the same problems before; I believe their technology and experience will help us to tackle this problem."

During the seminar, Japanese municipal officials from Tokyo, Kawasaki, Yokkaichi in Mie Prefecture and Kitakyushu discussed their experiences in overcoming past environmental pollution.

Japan suffered from severe pollution due to its economic growth after World War II. What makes the Japanese experience special is that its technological advances helped to solve air pollution problem but also boosted many industries, Tetsushige Nishio, professor of Meiji University and a former deputy environment minister, said at the seminar.

"As strict regulations such as meeting the requirements of the world's strictest standards on automobile emissions, introducing pollution-related health damage compensation, and the 'eco-car' subsidy program came into force, it promoted innovation in automobile industry", Nishio said.

However, Chinese media were not invited to attend the seminar, a move that Sun explained as because they want to focus on discussion without media interference.

Since 1979 JICA has been involved in China, helping the country's rapid economic development and conducting technical cooperation projects including promoting municipal solid waste recycling and a circular economy.

The organization is now helping to monitor and reduce the PM2.5 density in Xi'an through the experiences of Kyoto.

The Japan-China Economic Association has built a network of some 400 business people and companies from both sides to improve the air quality in China. The group dispatches experts from China to share experiences and makes a list of the possible technology and equipment assistance.

Besides Japan, China also seeks international cooperation with the US. Earlier this month, Beijing signed the first two-year agreement on air quality improvement with California, which is viewed as a model for vehicle emission standards and renewable energy policies. 

Speaking at Tsinghua University, California Governor Jerry Brown called for a partnership to develop technologies to reduce greenhouse gases.

"Reducing pollution takes great political struggle. We know in America it's not easy, so it won't be easy in Beijing. But to the extent that we can help, we would like to help," Brown said

The majority of monitoring equipment comes from the US instead of Japan as many Chinese companies are reluctant to buy Japanese products after the anti-Japanese protests over the disputed islands in September last year.

Setting mistrust aside

The problem between the two countries is an issue of trust, experts said.

In the summer of 2008, the American embassy in Beijing began issuing its own reading for PM2.5 levels. Wu Xiaoqing, the vice minister for environmental protection, openly said the data could lead to "social consequences in China and asked the embassy to restrict access to it." However, the readings remain widespread and are welcomed by Chinese citizens.

During the embassy's briefings, Okazaki is often asked if China's environmental monitoring data about PM2.5 can be trusted. Some urge the Japanese embassy to publish its own data to the public.

In response, Okazaki explained that the embassy did not have a monitoring plan at this moment, as it is located close to the US embassy. He collates the data from both the Chinese authorities and the US embassy and publishes the results on the embassy's website.

"From the analysis we can see the data from both side shows similar pattern and we will follow this trend," Okazaki said.

At the briefing, Okazaki called for Japanese residents to save energy and use public transportation to tackle air pollution, and also suggested Japan expand environmental cooperation with China.

The PM2.5 concentration in January 2012 in the North Kyushu area was not significantly higher than that in January 2011, according to Asuka Jusen, a professor at the center for Northeast Asian Studies at Tohoku University, citing analysis from Japan's research organizations.

"Therefore, there is no need to have an irrational fear of trans-boundary PM2.5, and nobody should play the blame game," Jusen wrote in a paper about Sino-Japanese collaboration on air pollution this month.

He said he believes the Sino-Japanese collaboration would provide incentives for both Japan and China to participate, which will likely have a greater importance in terms of the long-term political and economic impact on both countries

Zhou Shizhou, a professor at the Institute of Political Science at the Chinese Academy of Social Sciences, told the Global Times that the key to winning trust is to publish truthful environmental data for the public.

"Residents need the data to adjust their lives accordingly," Zhou said. "Releasing the information in a less clear way would only lead to trust issues for the government."