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Effect of nitrogen dioxide and sulfur dioxide on viability and morphology of oak pollen
Author(s) -
Ouyang Yuhui,
Xu Zhaojun,
Fan Erzhong,
Li Ying,
Zhang Luo
Publication year - 2016
Publication title -
international forum of allergy and rhinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.503
H-Index - 46
eISSN - 2042-6984
pISSN - 2042-6976
DOI - 10.1002/alr.21632
Subject(s) - pollen , nitrogen dioxide , sulfur dioxide , carbon dioxide , air pollutants , medicine , toxicology , botany , environmental chemistry , zoology , air pollution , chemistry , biology , ecology , organic chemistry
Background Nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ) generated by excessive coal combustion and motor vehicle emissions are major air pollutants in the large cities of China. The objective of our study was to determine the effects of the exposure of oak pollens ( Quercusmongolica ) to several concentrations of NO 2 or SO 2 . Methods Pollen grains were exposed to 0.5 ppm to 5.0 ppm NO 2 or SO 2 for 4 hours and assessed for morphological damage by field emission scanning electron microscopy and for viability using the trypan blue stain. Morphological changes in pollen grains were also examined after contact with acid solutions at pH 4.0 to pH 7.0. Results Exposure to NO 2 or SO 2 significantly damaged pollen grains at all concentrations investigated, compared to exposure to air; with exposure to concentrations of 0.5 ppm to 2 ppm resulting in fissures or complete breaks in the exine and a concentration of 5 ppm resulting in complete breakdown and release of pollen cytoplasmic granules. Significantly greater amounts of pollen grain were damaged after exposure to SO 2 (15.5–20.4%) than after exposure to NO 2 (7.1–14.7%). Similarly, exposure to NO 2 or SO 2 significantly decreased the viability of pollen grains, compared with exposure to air; with SO 2 being slightly more detrimental than NO 2 . Exposure to acid solutions also induced pollen damage, which appeared to be pH‐dependent (from 24.6% at pH 6.0 to 55.8% at pH 4.0; compared to 3.8% at pH 7.0). Conclusion Short‐term exposure of oak pollen to high concentrations of SO 2 or NO 2 significantly increases their fragility and disruption, leading to subsequent release of pollen cytoplasmic granules into the atmosphere. These results suggest that heightened air pollution during the oak pollen season may possibly increase the incidence of allergic airway disease in sensitized individuals by facilitating the bioavailability of airborne pollen allergens.