After suffering through spring, the 10 percent of the population who suffer cedar pollen allergies might now have to face a runny-nose nightmare in autumn.
Cedars have grown more and larger pollen sacs than usual this year due to the hot summer, said Norio Sahashi, a professor of pharmaceutical sciences at Toho University and an expert on pollen allergies. This means that pollen might be released in late October.
“I have observed (cedar pollen sacs) for more than two decades, and the number of sacs this year is probably the second or third largest,” Sahashi said.
Usually, cedar pollen grains grow in microspore sacs in late October and November and are released after Valentine’s Day, causing allergic reactions that include sneezing, a runny nose and itchy eyes.
But trees also can release pollen on a warm autumn day, Sahashi said, adding that the condition of the trees this year is similar to those in the fall of 1994, when large amounts of pollen were released and allergic reactions were reported from the Tohoku to Kyushu regions.
“The number of patients will be much smaller than in the spring, of course,” he said. “But sensitive patients will suffer allergy symptoms in the fall.”
According to Sahashi, high temperatures in July are particularly effective in making cedars produce more pollen.
Sahashi’s scenario matches this year’s situation in Tokyo, where 20 percent of people suffer pollen allergies.
In July, the mercury rose above 30 degrees for 26 consecutive days, compared with a July average for the past 30 years of 14.8 days, according to the Meteorological Agency.
And the daytime high exceeded 30 degrees for 10 days this month, including Tuesday, compared with the September average for the last three decades of 6.9 days, the agency said.
Scientists also fear a backlash this fall, caused by last spring’s particularly light pollen season.
In the spring, the Tokyo Metropolitan Government’s pollen count was 10 percent that of last year due to the comparatively cooler summer of 2003.
Experts are worried about the overall increase in temperatures, believed to be caused by global warming and the so-called heat-island effect in urban areas.
“There is no doubt the number of patients will increase.” Sahashi said. “There will be few factors that can push down the amount of pollen.”
Cedar pollen allergies were first reported in Japan in 1963, after a large number of cedars were planted in postwar afforestation campaigns led by the Forestry Agency.