• Published: March 31, 2024 Received: July 04, 2023 Available on J-STAGE: June 07, 2024 Accepted: December 26, 2023 Advance online publication: - Revised: -

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Oxidative stress due to exposure to PM_2.5 that generates reactive oxygen species (ROS) is one of the pathways leading to morphologic changes and lung function decrements that are linked to exacerbation of asthma and chronic obstructive pulmonary disease. Biomass burning (BB) is one of the largest sources of PM with its expected induction of ROS through exposure. Open burning of agricultural residues is widely conducted in September and October in Japan, but it is unclear to what extent the oxidative stress induction ability (OSIA) is increased during the active BB season compared to other seasons, when the effects of BB are different. In this study we conducted heme oxygenase-1 assays on PM_2.5 samples collected during the active BB season (October 2015) in Tsukuba, Japan, to clarify the influence of BB on OSIA. On average, BB particles were estimated to be responsible for 25% of PM_2.5, and 80% of OSIA in October 2015. At that time, PM_2.5, BB particles and OSIA were up to two times, eight times and seven times higher, respectively, than during seasons of low BB activity. Thus, elevated concentrations and OSIA are considered to arise mainly from BB particles. The results indicate that management of BB activity is important for good air quality and public health.

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