Chamber and Field Studies demonstrate Differential Amb a 1 Contents in Common Ragweed Depending on CO₂ Levels

ABSTRACT

Although atmospheric carbon dioxide (CO₂) has no apparent direct effect on human health, it does have direct effects on plants. The present study evaluated the influence of increased CO₂ levels on the concentration of allergens from common ragweed pollen by setting up a chamber study to model future air conditions and a field study to evaluate current air conditions. For the chamber study, we established 20 ragweed plants in an open-top chamber under different CO₂ levels (380–400, 500–520, 600–620, and 1,000–1,100 parts per million [ppm]). For the field study, we established ragweed plants in rural (Pocheon, Gyeonggi-do; mean CO₂ 320±54.8 ppm) and urban (Gangnam, Seoul; mean CO₂ 440±78.5 ppm) locations. Seeds of the common ragweed (Ambrosia artemisiifolia) were obtained from Daejin University. The Amb a 1 protein content of pollen extracts was quantified using a double sandwich enzyme-linked immunosorbent assay. In our chamber study, the median concentration of Amb a 1 in pollen increased with increasing in CO₂ concentration (1.88 ng/µg in 380–400 ppm CO₂; 3.14 ng/µg in 500–520 ppm CO₂; 4.44 ng/µg in 600–620 ppm CO₂; and 5.36 ng/µg in 1,000–1,100 ppm CO₂). In our field study, we found no significantly different concentration of Amb a 1 between the pollen extracts at the Pocheon (mean±standard deviation, 1.63±0.3 ng/µg pollen in 320±54.8 ppm CO₂) and the Gangnam (2.04±0.7 ng/µg pollen in CO₂ in 440±78.5 ppm CO₂) locations, although the concentration of Amb a 1 was increased in the Gangnam than in the Pocheon locations. Our results suggest that future increases in CO₂ levels to more than 600 ppm will significantly elevate the Amb a 1 content in common ragweeds, although the current different CO₂ levels do not cause differences in the Amb a 1 content of ragweed pollen.