Pollen set to make hay fever while the sun shines

Some people don’t have to witness the days getting longer to know spring is just around the corner. Their sneezing and runny noses are proof enough.

The cedar pollen season has begun in western Japan and the southern Kanto region, and the pollen count this year is expected to exceed the average for the past decade in the Kanto, Tokai and Kinki regions.

Although improved medicines can alleviate hay fever symptoms, the allergy still drags many down.

Hay fever was not a common occurrence until some 20 years ago. It has since spread across the country.

In 2001, Minoru Okuda, president of the Japan Allergy Foundation, conducted a nationwide study on the allergy, sending questionnaires to 10,000 randomly selected people. According to the research, it is estimated that 13.5 percent of the population are hay fever sufferers.

Many people wonder why there has been such a dramatic increase, and whether there is a way to combat its root cause.

“The number of patients grew dramatically from around the 1970s to 1980s,” Okuda said. “The speed of increase is not so high now, but I believe the number is rising gradually.”

In Tokyo, pollinosis sufferers have almost doubled over the past decade, from 10 percent of the population in 1986 to 19.4 percent in 1996, according to the Tokyo Metropolitan Government.

The increase comes amid a rise in the amount of pollen in the atmosphere from maturing cedar and other trees that were planted in huge numbers after the war. Other factors, including air pollution, changes in diet and mental stress, may also trigger reactions to pollen.

Norio Sahashi, a professor of biology at Toho University and a pollen specialist, said that from the 1970s to the 1980s, the Kanto region saw an explosive increase in airborne pollen every three years. This triggered a sudden increase in hay fever.

In recent years, the intervals between explosive pollen releases has grown shorter, Sahashi said. In the 1990s, high counts were registered every two years, and since 2000 have been an annual occurrence.

Sahashi said one possible cause is global warming, because more cedar flowers bloom and produce pollen when the preceding summer is hot and sunny. Since there is little likelihood that global warming will be fully reversed, pollen will continue to increase unless countermeasures are taken, he warned.

“Pollen cannot be reduced naturally,” Sahashi said. “The only solution is to cut down trees.”

Cedar forests cover about 4.5 million hectares of Japan, an area equal to that of Kyushu, according to Sahashi. The trees were planted for lumber after World War II, but cheaper wood started to be imported in the 1960s, lowering the demand and price for domestic timber. As a result, many cedar forests are not logged or thinned out and have become major pollen producers.

Faced with increasing concerns that hay fever is becoming a social problem, the government is getting serious.

In 1995, Liberal Democratic Party members who suffer hay fever set up a group to address the issue of allergies, including pollinosis.

House of Representatives lawmaker Shinya Ono, who heads the secretariat of the 60-member group, wants the government to increase spending for the fight against allergies.

Through the group’s efforts, the budget for related projects was increased to 7.3 billion yen in fiscal 2002 from 268 million yen in fiscal 1995, Ono said.

The group has also worked to foster interministry cooperation, as opposed to government bodies individually studying the hay fever and pollen problems, he added.

Under one project, the forestry agency introduced prefectural subsidies in fiscal 2002 for thinning out municipally owned cedar tracts near cities. The project, which targets trees that have more pollen-releasing male flowers, aims to reduce pollen at its source, according to agency official Tomohiro Oishi.

He said 60 million yen was allocated for the project, which covers up to 600 hectares of cedar forest nationwide.

The Forest Tree Breeding Center, an independent administrative institution, has meanwhile collaborated with prefectural governments to develop 57 kinds of cedar that produce less pollen.

The agency and prefectures will encourage the planting of these trees, Oishi said.

“These cedars are for replacing existing forests. They are expected to help alleviate the hay fever problem in the long term,” Oishi said. “But it will take decades.”

Local governments have also been struggling with the pollinosis problem.

Hiroyuki Oyama, an official in the Tokyo Metropolitan Government’s agriculture, forestry and fishery division, said researchers came up with a unique way to reduce pollen — a chemical that restricts its production.

In 2001, the metropolitan government’s experimental forestry station succeeded in reducing the pollen of young trees by 90 percent by injecting maleic hydrazide, Oyama said.

Based on the favorable results, a pilot project was developed in which the chemical was to be injected into 20,000 cedars in Tokyo’s parks in fiscal 2002.

But the plan was put on hold, Oyama said, because a substance found in an agricultural chemical similar to maleic hydrazide was suspected of being toxic. Now the metropolitan government is discussing whether to stop the project altogether due to safety concerns.

“Some suggested that other chemicals be used, but they are more expensive and it costs too much to inject them into trees,” Oyama said.

The most workable solution so far has been to plant trees that produce less pollen, even though this will take a great deal of time, he said. The metropolitan government is giving away seeds of cedar trees that emit less pollen to companies that sell saplings.

There are 20,000 hectares of cedar forest in Tokyo, mostly privately owned, Oyama said. Because lumber prices are too low to make a profit, owners don’t want to cut down the trees, and replanting has not made much progress.

The LDP’s Ono agrees that a major cause of today’s hay fever epidemic stems from the nation’s postwar lumber pursuit, which emphasized cedar.

Forestry efforts more in line with ecological diversity will help solve the hay fever problem, he said.

At the Environment Ministry, researchers have also been looking into the relationship between air pollution and health. According to a ministry report on the impact of diesel exhaust in 2001, experiments using guinea pigs showed that exhaust particles triggered allergic inflammation of the nose.

Hay fever specialist Yozo Saito, a doctor at Kamio Memorial Hospital in Tokyo, said air pollution and a diet rich in fat and protein may also trigger hay fever.

He said city dwellers are more inclined to have hay fever, as 19.4 percent of Tokyo residents are sufferers, which is higher than the national average.

Diesel exhaust particles in the air and road asphalt, which does not absorb pollen, may provide conditions that induce hay fever, he added.

“In other parts of the world, the number of hay fever sufferers has increased in accordance with urbanization,” Saito said, and further research on the link between the allergy and the environment is necessary.