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Diurnal variation in the proinflammatory activity of urban fine particulate matter (PM _2.5) by in vitro assays.

ABSTRACT: Background: Ambient particulate matter (PM) smaller than 2.5 µm in diameter (PM _2.5) undergoes diurnal changes in chemical composition due to photochemical oxidation. In this study we examine the relationships between oxidative activity and inflammatory responses associated with these diurnal chemical changes. Because secondary PM contains a higher fraction of oxidized PM species, we hypothesized that PM _2.5 collected during afternoon hours would induce a greater inflammatory response than primary, morning PM _2.5. Methods: Time-integrated aqueous slurry samples of ambient PM _2.5 were collected using a direct aerosol-into-liquid collection system during defined morning and afternoon time periods. PM _2.5 samples were collected for 5 weeks in the late summer (August-September) of 2016 at a central Los Angeles site. Morning samples, largely consisting of fresh primary traffic emissions (primary PM), were collected from 6-9am (am-PM _2.5), and afternoon samples were collected from 12-4pm (pm-PM _2.5), when PM composition is dominated by products of photochemical oxidation (secondary PM). The two diurnally phased PM _2.5 slurries (am- and pm-PM _2.5) were characterized for chemical composition and BV-2 microglia were assayed in vitro for oxidative and inflammatory gene responses. Results: Contrary to expectations, the am-PM _2.5 slurry had more proinflammatory activity than the pm-PM _2.5 slurry as revealed by nitric oxide (NO) induction, as well as the upregulation of proinflammatory cytokines IL-1β, IL-6, and CCL2 (MCP-1), as assessed by messenger RNA production. Conclusions: The diurnal differences observed in this study may be in part attributed to the greater content of transition metals and water-insoluble organic carbon (WIOC) of am-PM _2.5 (primary PM) vs. pm-PM _2.5 (secondary PM), as these two classes of compounds can increase PM _2.5 toxicity.

SUBMITTER: Lovett C

PROVIDER: S-EPMC6171724 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Chiang Mai encounters severe pollution during the wildfire season. Wildland firefighters encounter various hazards while engaged in fire suppression operations, which encompass significant exposure to elevated concentrations of air pollutants resulting from combustion, especially particulate matter. The adverse effects of wildfire smoke on respiratory health are a significant concern. The objective of this study was to examine the potential adverse effects of PM2.5 exposure on the respiratory function and DNA damage of wildland firefighters. This prospective cohort study conducted in Chiang Mai from January to May 2022 planned to evaluate the health status of wildland firefighters during the pre-peak, peak, and post-peak ambient air pollution seasons. The measurement of PM2.5 was done at every forest fire station, as well as utilizing data from the Pollution Control Department. Participants received general health examinations, spirometry evaluations, and blood tests for DNA damage analysis. Pair t-tests and multiple regression models were used to examine the connection between pulmonary function parameters (FVC, FEV1) and PM2.5 concentration, with a significance level of P < 0.05. Thirty-three peak-season and twenty-one post-peak-season participants were enrolled. Four pre-peak-season wildland firefighters had FVC and FEV1 declines of > 15%. Multiple regression analysis showed a negative association between PM2.5 exposure and FVC% predicted (- 2.81%, 95% CI - 5.27 to - 0.34%, P = 0.027) and a marginally significant negative correlation with FVC (- 114.38 ml, 95% CI - 230.36 to 1.59 ml, P = 0.053). The remaining pulmonary measures showed a statistically insignificant decline. There were no significant changes in DNA damage detected. Wildland firefighters suffered a significant decline in pulmonary function associated with PM2.5 exposure. Spirometry is crucial for monitoring and promptly identifying respiratory issues that occur during wildfire seasons. Further research is recommended to explore DNA damage alterations and their potential association with PM2.5.

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Diurnal variation in the proinflammatory activity of urban fine particulate matter (PM _2.5) by in vitro assays.

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Dataset Information

Diurnal variation in the proinflammatory activity of urban fine particulate matter (PM 2.5) by in vitro assays.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Diurnal variation in the proinflammatory activity of urban fine particulate matter (PM _2.5) by in vitro assays.