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Wednesday, Feb. 13, 2008
Pollen set to come out of hibernation
By KAHO SHIMIZU
For sufferers of "kafunsho" (pollen allergy), it's hay fever season again.
The past decades have seen more and more people suffer allergic reactions to pollen, especially from Japan's millions of cedar trees. According to the Environment Ministry, cedar pollen levels this spring in eastern Japan will be 1.5 to three times over last year because last summer was hot and sunny. Pollinosis sufferers are desperate for a good remedy.
What is hay fever?
It is defined as an acute inflammation of the eyes and upper respiratory tract, often linked to pollen released from trees, weeds and grasses from spring to fall.
A high intake can trigger allergic reactions in people whose immune system is overactive. Symptoms range from runny noses to blocked sinuses, sneezing and itchy eyes. Pollen release depends on when plants bloom.
Cedar and cypress pollen is usually a spring problem, while pollen from grasses circulates in summer and fall.
What differentiates pollinosis in Japan from other areas?
Unlike in the United States, where ragweed is a main pollen source, or Europe and its grassy pollen, cedar and cypress trees cause the most suffering in Japan.
This is especially true with cedar trees, which were planted nationwide right after the war to resupply the nation with timber. Those forests have reached their point of maturity in terms of pollen release, and meanwhile the logging industry has waned due to cheaper lumber imports.
Nearly 20 percent of the population, or more than 20 million people, are believed to suffer from pollinosis, although there is no up-to-date official figure.
Toru Imai, chief otolaryngologist at St. Luke's International Hospital in Tokyo, said Japan is known for its large number of sufferers in cities. Unlike that from grass, pollen from cedar trees, which were planted at the edge of urban areas, can fly long distances, he said.
Cedar and cypress forests cover 30,000 hectares in the Tama district in western Tokyo. The Tokyo Metropolitan Government believes winds carry a large quantity of their pollen to the central part of the metropolis.
Why are city dwellers considered more likely to suffer pollinosis?
Experts believe the mechanism that triggers the allergic reaction is linked to environmental and living conditions.
One factor they point to is air pollution. St. Luke's Imai said tests on animals show that vehicle exhaust worsens pollinosis symptoms, but no one is certain why some people suffer.
Asphalt pavement has been blamed for making the situation worse in cities because it does not absorb pollen, allowing any that has settled the chance to become airborne again.
What kind of medical treatment is popular in Japan?
According to Imai, more people are seeking early treatment, taking medicine before symptoms appear.
Sufferers are advised to take antihistamine tablets about a week before they become exposed to heavy concentrations of pollen.
Antihistamines developed from the 1940s to the 1970s can produce side effects, including drowsiness, fatigue, dry mouth and glaucoma. Newer antihistamines now widely available do not. Users, however, must be careful when taking the drug along with other pharmaceuticals, including cold medicines and antidepressants.
Newly developed antihistamines include ketotifen fumarate, an ingredient in the popular over-the-counter medicine Zaditen, and loratadine, which is widely known as Claritine, a popular prescription pill.
Antihistamines include pills, nasal drops and sprays and eyedrops. Although prices vary, many over-the-counter medicines cost between ¥1,000 and ¥2,000.
Imai suggests that sufferers first go to clinics to identify the cause of one's allergy and then get the most appropriate medication.
Are there any cures or symptom alleviators other than medicines?
Hyposensitization therapy is a long-term treatment that involves regular injections of small amounts of pollen extract so the body can adjust and not suffer allergic reactions.
Because sufferers will have to have injections weekly for the first few months and although the frequency is later reduced to once a month, the treatment takes time to be effective.
Another tack is laser treatment on the nasal passage to disengage the mucous membrane so it won't react to pollen. But because this does not change a person's constitution, it may not work well for everybody, and some people cannot undergo it because of the shape of their nasal passage.
Above all, Imai said avoiding pollen remains the most effective and basic way to alleviate symptoms.
Sufferers should first think about wearing protective masks and staying indoors during the day before jumping to such treatment.
What is the government doing to alleviate the problem?
The Environment Ministry and municipal governments issue pollen forecasts.
The ministry Web site at kafun.taiki.go.jp/ maps the observed pollen count on a regional basis. The site is only available in Japanese.
The Tokyo Metropolitan Government provides regional up-to-date pollen count forecasts in e-mail to registered cell phone users.
The Forestry Agency plans to log cedar and replace them with new strains that were developed to release less pollen.
Cedar forests cover about 4.5 million hectares. According to an agency study, the Kanto and Kansai regions trace their pollen concentrations to a combined 95,000 forested hectares. Here, too, plans are afoot for the agency and local governments to log the mature cedar and replant forests with the new strains.
The goal is to halve problematic forests in those areas by 2017.
Companies are launching new products to ease hay fever symptoms. What pollen allergy-related goods and services are drawing attention?
The market for pollinosis-related products and services is expanding, although there is no official data on how big it has become.
In addition to conventional products, including masks, nasal sprays and goggles, clothiers are introducing clothes and coats made of pollen-proof fabric.
There are also hundreds of supplement tablets, candies and teas touted as being able to ward off hay fever.
Travel agencies are running so-called pollen retreat tours, offering destinations such as Hokkaido and Okinawa, where cedar pollen levels are low.