Temporal Variability of Particulate Matter Across Garlic Cultivation Periods: A Two-Year Monitoring Study in a Small-Scale Garlic Field in Rural South Korea

Ambient particulate matter (PM) concentrations at agricultural monitoring sites may reflect field activities, meteorological conditions, regional background pollution, long-range transport, and secondary aerosol formation. This study characterized temporal variation in PM10 and PM2.5 concentrations measured at a single in-field station across calendar-defined garlic cultivation periods. PM, gaseous pollutants, and meteorological variables were continuously measured during 2024–2025 at a 1.41 ha garlic field in Danyang-gun, Republic of Korea. Daily means were calculated for days with at least 18 valid hourly observations. Six periods were examined: fertilization, growth, sowing, harvesting, tillage, and fallow. AR(2) time-series models were adjusted for temperature, relative humidity, wind speed, rain occurrence, season, and year, with fallow as the reference period. Adjusted daily mean PM concentrations differed significantly among periods. The largest adjusted differences relative to fallow occurred during the fertilization period: +37.09 μg/m3 for PM10 (95% CI: 24.60–49.58) and +20.65 μg/m3 for PM2.5 (95% CI: 13.82–27.48). Both fractions were also elevated during growth and sowing. Harvest estimates were positive but did not remain significant after Holm adjustment in the primary models, and inferential support varied across specifications. Tillage showed no consistent elevation. The exploratory NH3–PM2.5 association was stronger at lower temperatures but was not consistently supported in supplementary analyses. These findings characterize PM concentrations measured in the field across cultivation periods; the overlap with seasonal conditions limits attribution to individual agricultural operations.