Highly time-resolved measurements of element concentrations in PM₁₀ and PM_2.5: Comparison of Delhi, Beijing, London, and Krakow

Abstract. We present highly time-resolved (30 to 120 min) measurements of size-fractionated (PM₁₀ and PM_2.5) elements in two cities in Asia (Delhi and Beijing) and Europe (Krakow and London). For most elements, the mean concentrations in PM₁₀ and PM_2.5 are higher in Asian cities (up to 24 and 28 times, respectively) than in Krakow, and often higher in Delhi than in Beijing. Among European cities, Krakow shows higher elemental concentrations (up to 20 and 27 times, respectively) than London. The enrichment factor of an element together with the size distribution allows for a rough classification of elements by major sources. We define five groups: (1) dust-related, (2) non-exhaust traffic emissions, (3) solid fuel combustion, (4) mixed traffic/industrial emissions, and (5) industrial/coal/waste burning emissions, with the last group exhibiting the most site-to-site variability. Hourly maximum concentrations of Pb and Zn reach up to 1 µg m⁻³ in Delhi, substantially higher than at the other sites. We demonstrate that the high time resolution and size-segregated elemental dataset can be a powerful tool to assess aerosol composition and sources in urban environments. Our results highlight the need to consider the size distributions of toxic elements, diurnal patterns of targeted emissions, and local vs. regional effects in formulating effective environmental policies to protect public health.