An insight into recent PM1 aerosol light scattering properties and particle number concentration variabilities at the suburban site ATOLL in Northern France
The impact of aerosol particles in the PM1 size fraction (particles smaller than 1 µm) on climate is multifaceted. Black carbon, found exclusively in the PM1 aerosol fraction, is the most effective aerosol light absorber, contributing to local atmospheric warming. In contrast, sulfate aerosols and secondary organic aerosols predominantly have a cooling effect because they effectively scatter the visible spectrum of light. Furthermore, PM1 particles have been found to be highly effective cloud condensation nuclei, thereby increasing the albedo of clouds and extending their lifetime, thus promoting further aerosol-induced cooling. The potential health implications of PM1 particles are of particular concern, given their ability to penetrate deep into the lungs and enter the bloodstream (for particles <0.1 μm), with associated risks including cardiovascular, pulmonary, carcinogenic, and inflammatory diseases. Furthermore, these particles have the potential to contain significant quantities of potentially toxic compounds due to their high surface-to-mass ratio, and the mixture of these compounds is often not well understood, which further increases the risk of human exposure. However, the widespread use of aerosol optical measurement techniques (especially aerosol light scattering) may not be sufficiently effective for detecting all particles in the PM1 fraction, particularly with regard to number concentration, given that particles below 100 nm do not inherently interact with the visible spectrum of light.
This study examined the temporal variations in aerosol light scattering properties and particle number concentration (PNC) across different size modes in the PM1 fraction at the atmospheric site ATOLL in Lille, France (January 2018 to February 2023). Our observations revealed a statistically significant decrease in total scattering coefficient σsp, with the highest decrease rates occurring during summer. Although the backscattering coefficient σbsp underwent a significant decrease in winter, the overall value remained unchanged, indicating a relative enhancement of aerosol cooling potential at the site. The decline in total aerosol scattering suggests a reduction in the aerosol scattering mass at the site. Conversely, PNC exhibited a substantial increase in the concentration of particles sized 20-30 nm and 30-60 nm, leading to an overall increase in PM1 number concentration. The increasing trend was influenced by both traffic and photo-oxidation of gaseous precursors, as well as new particle formation, underscoring the need for a more comprehensive investigation of the detailed particle number size distribution to assess air quality and the health effects of increased ultrafine PNC at urban/suburban sites in Europe.
- Suchánková L.*, Crumeyrolle S., Bourianne E., Prokeš R., Holoubek I., Ždímal V., Chiapello I.: An insight into recent PM1 aerosol light scattering properties and particle number concentration variabilities at the suburban site ATOLL in Northern France. Sci. Total Environ. 2025, 959(January 10), 178190. doi.org/10.1016/j.scitotenv.2024.178190