The results of burning fossil fuels is no secret, however a recent study proved that as nitrogen oxides are released into the atmosphere at an increasing rate, common pollens become more allergenic.

NO2 is released during combustion, most commonly traced back to vehicles burning gas. To study its effect on ragweed, plant researchers from Helmoltz Zentrum München fumigated plants with various concentrations of NO2, and found that, when exposed, the allergen concentration increases.

"Our data showed that the stress on the plant caused by NO2 modulated the protein composition of the pollen," said first author Dr. Feng Zhao in a release. "Different isoforms of the known allergen Amb a 1 were significantly elevated."

The study also determined that the pollen from NO2 treated plants have a significantly increased binding capacity to specific IgE (Immunglobulin E) antibodies of individuals allergic to Ambrosia. This is often the beginning of an allergic reaction in humans. According to the release, IgE refers to a class of antibodies considered to be the main cause of allergic reactions in the body. If an IgE molecule binds to an allergen, it can induce so-called mast cells to release histamine, which ultimately triggers the allergic reaction. However, IgE is supposed to defend against parasites and worms.

Along with this discovery, a protein, previously unknown to be an allergen in Ambrosia; was identified in the pollen of the plants fumigated with NO2. The protein that presented itself was observed to have a strong similarity with that from a rubber tree.

"Ultimately, it can be expected that the already aggressive Ambrosia pollen will become even more allergenic in the future due to air pollution," said study leader Dr. Ulrike Frank, summarizing the results of the release.

Frank and her team at the Institute of Biochemical Plant Pathology have long been conducting research on Ambrosia, which has been found to once invade Europe through imported birdseed, and is now wide spread as a result of climate change. In the United States, Ragweed pollen is very aggressive and the main cause of hay fever and other allergies. Ambrosia blooms late in the summer and inevitable lengthens the "allergy season."

"After studies have already shown that ambrosia growing along highways is clearly more allergenic than Ambrosia plants growing away from road traffic, we could provide a reason for this," said Frank in a release. "Since in nature and along roads hundreds of parameters could play a role, until now the situation was not entirely clear."

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