As CO2 Emissions Rise, So Will Pollen Counts And Asthma Attacks

Climate change could cause pollen counts to more than double over the next 30 years, according to an ongoing Rutgers University study.

The research, presented at the American College of Allergy, Asthma and Immunology conference in November, tested how allergenic plants respond to conditions that mimic those of a warming world, including changing weather patterns and increases in temperature and carbon dioxide.

Based on these tests, the researchers predict pollen counts could reach 21,735 particles of pollen per cubic meter by 2040 — a drastic spike from 2000’s average of 8,455. An “extremely high” pollen count for trees — which account for most of spring pollen — is 1,500. The research also predicts that, as spring arrives earlier due to climate change, pollen seasons will begin earlier as well. In 2000, pollen production began April 14 and peaked May 1, but by 2040, the researchers predict production will start more than a month earlier, peaking by April 8.

Though the research is not yet published, it lines up with what scientists already know about plants’ reactions to increased carbon dioxide and temperature. A 2002 study in the Annals of Allergy, Asthma and Immunology found that ragweed, which causes most fall allergies, produces 61 percent more pollen when grown in an atmosphere with double the normal amount of carbon dioxide. A 2006 study on the same plant produced similar results. Pollen produced under high CO2 conditions may even be more highly allergenic, as Clifford Bassett, an allergist and ACAAI fellow, told CNN:

As you increase CO2, it tells the allergenic plants to produce more pollen to the tune of three to four times more, and the pollen itself, we think, may actually be more potent.

Pollen records have been off the charts over the last few years, as warm weather arrived early in many states. Last year, pollen season began early due to a mild winter and early onset of warm weather, and pollen counts across the U.S. were extremely high. In Atlanta, the pollen count reached 9,369 particles per cubic meter of air, shattering the city’s 1999 record of 6,013. Vanderbilt University in Nashville recorded a pollen count of 11,000, the highest count recorded since the university began counting 12 years ago. Many places saw similarly high counts and early pollen releases in 2010 and 2011. This year has already seen early spikes and dips in the pollen count, due to temperatures rising and falling — some places, like Gainesville, Fla., logged high pollen counts as early as January.


Higher pollen counts aren’t just uncomfortable for allergy sufferers — since allergies can trigger asthma attacks, higher pollen counts and earlier pollen releases can have serious implications for those suffering from asthma, and could even be connected to the global rise of asthma cases.

As the climate warms and springs and summers become longer, allergy seasons in fall, spring and summer could extend as well, exacerbating allergy symptoms. When allergy sufferers have no respite from symptoms, it makes them more prone to serious allergy attacks than if they had had a break between seasons.