Abstract
In spite of a dramatic decrease in anthropogenic emissions, ambient concentrations of major pollutants have not changed within many urban locations. To clarify the relationship between ambient air quality trend and the population exposures, we compared the intraurban versus temporal variability of the collocated measurements of five major air pollutants including particulate matter (PM) with an aerodynamic diameter <10 µm (PM₁₀), < 2.5 µm (PM₂.₅), tropospheric ozone (O₃), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂), in Kraków, Poland, during the 2000-2010 period. Strong seasonal trends and overall absence of spatial heterogeneity in PM₁₀ and PM₂.₅, except in the traffic monitoring site, were observed across the monitoring network. The range of median PM₂.₅ concentrations during winter (54-64 µg/m³) was 3- to 4-times higher than the summer medians (15-26 µg/m³) across the sites during 2009-2010. Furthermore, large proportion of PM₁₀ appears to be comprised of PM₂.₅ (PM₂.₅/PM₁₀ concentration ratios range, 0.5-0.7). At each monitoring site, the Pearson's correlation coefficients between PM₂.₅ and PM₁₀ ranged between 0.944 and 0.963, suggesting a health-relevance of PM10 monitoring. One ln-unit increase in PM₁₀ was associated with 92%-100% increase in PM₂.₅ concentrations in the same location. While PM₁₀ did not demonstrate a clear temporal trend, SO₂ concentrations steadily declined by 40% during the 2000-2010 period. Summertime median NO₂ concentration was acutely elevated (70 mg/m³ vs. 22 mg/m³) at the traffic oriented site compared to the city's central monitoring site. The traffic and the industrial sites were associated with highest number of days during which 24-hour mean PM₁₀ and PM₂.₅ concentrations exceeded the European Union standard. Steadily growing contributions by vehicular emissions appear to be associated with the absence of clear trend in PM₁₀. Current practices of air quality control within Kraków may not be adequate for the protection of the public's health.