Investigation of Air Pollution in Al Bayda, Libya: Exposure Levels, Temporal Variability and Potential Sources

The association between exposure to high levels of PM₂.₅ and health impacts is extensively studied and well-documented. Al Bayda, Libya, faces recurring air quality issues due to open waste burning, particularly during nighttime hours. To date, no comprehensive assessment of PM₂.₅ concentrations has been conducted in this area. This study aims to characterize PM₂.₅ concentrations in Al Bayda, Libya, by assessing exposure levels, temporal variability, and potential sources. Concentrations of PM2.5 were recorded every minute during 2023 and 2024 using PurpleAir-II-SD air quality monitors. For the same period, meteorological hourly data were also obtained from Al Bayda Weather Station. The data were analyzed to assess temporal variability and were compared with WHO guidelines and US-EPA standards. The WHO 24-hr standard was exceeded on 118 days (41%) in 2023 and 144 days (44%) in 2024. Annual average PM2.5 concentrations were 15.4 μg/m3 and 17.4 μg/m3 in 2023 and 2024, respectively, exceeding both the WHO air quality guidelines and the US-EPA standards. Diurnal trends of PM2.5 concentrations and wind speed indicate that PM2.5 levels are strongly influenced by meteorological conditions. Monthly PM2.5 concentrations and weekday boxplots suggest that the timing of elevated concentrations does not follow a consistent or systematic pattern. Together, the observed nighttime increases are consistent with intermittent local emission activities, most likely open waste burning. The findings indicate that PM₂.₅ concentrations in Al Bayda frequently exceeded WHO guidelines and US-EPA standards and were strongly influenced by meteorological conditions. Chemical composition analyses are recommended to further investigate the potential sources of PM₂.₅.