On a blustery Saturday in late February, social media was abuzz with videos and photos of what looked like smoke billowing from the mountains of western Tokyo. But these weren’t wildfires. The images captured vast plumes of pollen erupting from dense cedar forests, forming a fine yellow mist that spread across the landscape.

“Today’s pollen in Okutama: It’s rising from the trees like steam, and a yellow haze hangs over the entire mountain. If you’re heading this way, don’t forget your protection…!” user posted on X, accompanied by a short clip of pollen drifting through the treetops.

“It’s hard to see in this photo, but the mountains in Chichibu looked the same,” replied, sharing an image from the city in neighboring Saitama Prefecture.

Scenes like this have become a familiar springtime spectacle in Japan, where vast cedar and cypress forests release torrents of pollen each year — the sneeze-inducing legacy of a postwar tree-planting drive that reshaped the country’s mountains.

Early signs suggest this season — which typically peaks in March and lasts until May — may be particularly intense. Data from the Tokyo Metropolitan Government shows pollen dispersing at a faster pace than usual, especially in western Tokyo, where a large share of the season’s expected cedar pollen has already been recorded.

While a range of medicines, masks and other products help sufferers cope with 첹ڳܲԲō (hay fever), addressing the problem ultimately requires tackling its source in the forests. 

The government has launched a decade-long program to cut older trees and replant forests, while researchers develop low- and no-pollen cedar varieties and test pollen suppressants. But with a dwindling forestry workforce and much forest land tied to unknown or untraceable owners, it remains uncertain whether these efforts can produce the intended results.

“Like what people were posting on social media, the pollen was dispersing so heavily it looked almost like a wildfire,” says Toshiharu Suzuki of the tourism and industry division at the Okutama town office. “I only have mild hay fever myself at the moment, but this year feels particularly bad.”

In April 2023, during an Upper House committee meeting, then-Prime Minister Fumio Kishida declared war on hay fever. 

“Hay fever is now a problem that can be described as a social issue in Japan,” he said. “The government is convening a meeting of relevant Cabinet ministers to share information and coordinate effective measures. We are determined to deliver results.”

Japan’s cedar and, to a lesser extent, cypress forests are ubiquitous in the countryside, dominating its artificial woodlands. About 25 million hectares — roughly two-thirds of the nation’s land — are forested, of which about 10 million hectares are planted. Around 70% of...