BayCEER Workshop 2025

Spatial and temporal variability of ultrafine particle number concentrations and their link to air quality close to Munich airport in 2023

Airports can affect local air quality by emitting airborne ultrafine particles (UFP, Dp < 100 nm) that pose health risks. We studied UFP near Munich Airport for the full year 2023 using a multi-scale approach to assess community exposure and the atmospheric processes controlling dispersion and accumulation. Two residential sites (Freising north, Hallbergmoos south) located north and south of the airport were monitored. At each site a Mobility Particle Size Spectrometer (MPSS; 10–800 nm) measured particle number concentration (PNC) and particle size distribution (PSD) (see Seidler et al. 2024). O₃ and NOₓ were measured with Thermo 49i and N500 CAPS analyzers, meteorology with a ClimaVUE50 sensor, and traffic plus airport operation data were included.

We applied statistical methods across multiple timescales to explore interactions between local sources and atmospheric processes. Annual mean PNCs (10–800 nm) were similar at both stations: 8,900 ± 8,000 cm³ (median 6,800 cm³) north and 8,200 ± 8,500 cm³ (median 6,200 cm³) south, comparable to other European urban background sites. However, PNCs at the two sites were not correlated (slope = 0.13, R² = 0.02). We examined trends and relationships between UFP, traffic gases (NO, NO₂), surface O₃, and airport operations to assess airport impacts.

Seasonal variability (wind direction/frequency, boundary layer/mixing) influenced UFP transport, effects being more evident at the southern site; the northern site showed stronger influence from other particle sources. Diurnally, two PNC peaks coincided with urban rush hours and varied seasonally. We also analyzed event-specific periods (no road traffic, no air traffic). Overall, this study offers a year-long, multi-instrument assessment of the spatial and temporal variability of UFP near a major operational airport and its implications for nearby residential air quality.