Factors Influencing Particulate Matter Variability in an Urban Street in Chios

This study examines how traffic flow, suburban PM2.5 concentrations, noise and meteorological factors influence particulate matter levels in an urban street. Spearman’s correlation analysis reveals that urban PM10 concentrations are moderately and significantly correlated with traffic flow (ρ=0.574, p<0.001), highlighting vehicular non-exhaust emissions as an important source of coarse particles. Traffic flow also shows a weaker but positive relationship with urban PM1 (ρ=0.312, p=0.05), indicating more complex sources for finer particles. The correlation between urban PM fractions and suburban PM2.5 varies by particle size and source: Urban PM1 strongly correlates due to regional combustion sources; urban PM2.5 shows a moderate correlation; urban PM10 shows no significant correlation. Meteorological variables further modulate urban PM levels: wind direction moderately correlates with PM concentrations (ρ≈0.400), reflecting directional pollutant transport patterns; wind speed negatively predicts PM levels (ρ between -0.415 and -0.455), consistent with dispersion effects; and relative humidity positively influences PM concentrations (ρ=0.420–0.495), likely due to hygroscopic growth and secondary aerosol formation. These findings underscore the combined influence of traffic, regional pollution, and weather on urban particulate matter variability.