A novel method to suppress the dispersal of Japanese cedar pollen by inducing morphologic changes with weak alkaline solutions.

Inhalation of airborne pollen causes irritative symptoms in humans, known as pollinosis. The changing global climate and increased pollution contribute to enhance the release of pollen, thereby increasing the number of people suffering from allergies. We examined the effect of spraying weak alkaline solutions onto cedar trees, the main allergenic culprit in Japan, on pollen release. Weak alkaline solutions were sprayed onto Japanese cedar blossoms to disrupt the external walls of the pollen, and to induce swelling of the cytosolic components containing the nucleus. This morphologic change of the pollen grains depended on the pH of the suspending solution, with a threshold pH of near 7.5. As the breakdown of the external walls and swelling of the cytosolic components are inhibited by high osmolarity, the influx of water triggered the morphologic changes. Weak alkaline solutions sprayed onto cedar blossoms decreased the amount of pollen released from the anthers in a pH dependent manner. The addition of detergent to the sodium bicarbonate solution facilitated this effect on cedar pollen release. We suggest that spraying cedar and cypress forests with a weak alkaline solution might prevent the scattering of pollen that causes allergies in humans.