Every spring, pine trees unleash clouds of fine, yellow pollen that drift through the air and settle on cars, sidewalks, windowsills and other outdoor surfaces \u2014 what\u2019s been dubbed \u201cthe pollening.” <\/p>\n\n\n\n
The sight of the yellow dust often sparks complaints about sneezing, itchy eyes and congestion. But those symptoms, while real, are rarely caused by pine pollen.<\/p>\n\n\n\n
\u201cDue to its large size and smooth surface, pine pollen is less likely to be inhaled deeply into the respiratory system,\u201d said Robert Bardon<\/a>, a professor of forestry and environmental resources in the College of Natural Resources at North Carolina State University.<\/p>\n\n\n\n Pine pollen particles are relatively large compared to other types of tree pollen, with some grains measuring roughly the thickness of human hair.<\/p>\n\n\n\n Despite their size, pine pollen grains are specially adapted for travel: each grain has two air sacs that increase buoyancy, allowing them to be carried long distances by the wind and even float on water.<\/p>\n\n\n\n But their relatively large size affects how they interact with the respiratory system. When inhaled, they are less likely to penetrate deeply into the lungs and are more often trapped in the nose and throat.<\/p>\n\n\n\n The smooth surface of pine pollen further reduces its ability to adhere to the walls of the upper airways, potentially decreasing its overall allergenic impact.<\/p>\n\n\n\n \u201cI suspect that because pine and hardwood trees pollinate simultaneously, people often mistake visible pine pollen for the less obvious hardwood pollen actually causing their allergies,\u201d Bardon said. <\/p>\n\n\n\n In North Carolina, tree pollen season typically spans from February to May. Pine trees usually release their pollen between March and April, which coincides with the pollen release from hardwood trees such as oaks and hickories.<\/p>\n\n\n\n Hardwood pollen is microscopic, which allows it to be inhaled more easily and to travel deeper into the respiratory tract, reaching areas that larger pollen typically cannot.<\/p>\n\n\n\n The rough surface of hardwood pollen can irritate the respiratory system, causing discomfort in the nose, throat and airways.<\/p>\n\n\n\n While pine pollen is generally considered less allergenic, it can still cause reactions<\/a> in some people, especially those with sensitivities to other types of pollen or allergens.<\/p>\n\n\n\n