Anthropogenic "dust haze" in a megalopolis: changes in the composition and concentration of near-surface aerosol under local exposure

Dust aerosol plays an active role in the processes that determine the composition and properties of the atmosphere and influence Earth's climate, biogeochemistry of land and ocean [1,2]. Atmospheric dust is mainly of natural origin and is formed during dust and sand storms in arid and semiarid regions. The contribution of mineral dust to the global aerosol load is ~ 26 million tons [1]. In the troposphere, dust negatively affects the ecosystems, the health and livelihoods of the population [3].

Atmospheric transport of dust particles from areas of dust storms to neighboring regions often causes the appearance of dust haze. However, in large cities remote from the regions that emit mineral dust, the "dust haze" effect can be initiated by local anthropogenic sources (construction and reconstruction facilities). This is increased by the specific features of a large city (special wind conditions, deep urban canyons, urban landscapes, etc.).

The work studies variability in aerosol concentration, its size distribution and elemental composition in atmospheric near-surface layer in Moscow during the action of intensive construction points and the occurrence of local "dust haze". The data of continuous observations of near-surface aerosol composition carried out at the Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS) are analyzed for the summer of 2021 and 2024. Two episodes of heavy air dusting near the IAP RAS in the center of Moscow, differing in the duration and power of the sources, are discussed [4].

Under affect of those dust construction sources, the maximal values of PM₁₀ aerosol concentration exceeded the maximum permissible concentration (MPC) values: up to 14-38 MPC_S and up to 5-9 MPC_D (single MPC_S=300 µg/m³ and daily MPC_D=60 µg/m³).

Also, the sized and elemental composition of near-surface aerosol in the center of megalopolis during the action of local construction sources has been studied. The similarity of the particle size distribution functions for arid aerosol in Kalmykia and urban aerosol at the time of the highest intensity of local construction sources was found. As to elemental composition, the urban aerosol during the operation of construction sources and the arid aerosol of Kalmykia were similar in terms of the high content of lithophilic elements: aluminum Al, barium Ba, lithium Li, magnesium Mg, sodium Na, potassium K, calcium Ca, iron Fe, phosphorus P, strontium Sr, thorium Th, uranium U, lanthanum La, etc. However, in urban dust aerosols, the increased concentrations of potentially toxic anthropogenic elements have been recorded (metalloids and heavy metals): tungsten W, vanadium V, molybdenum Mo, nickel Ni, copper Cu, zinc Zn, cadmium Cd, and also lead Pb, tin Sn, antimony Sb, bismuth Bi. They are typical for road dust and for dust aerosol of Moscow as whole. 

Estimates of the power of such local construction aerosol sources and their negative factors in the conditions of "dusty haze" in a large city are discussed.

1. Kok J.F. et al.  Nat. Rev. Earth Environ. 2023. 4, 71–86. https://doi.org/10.1038/s43017-022-00379-5.
2. Mahowald N.M. et al. Atmos. Chem. Phys. 2010. 10, 10875–10893. https://doi.org/10.5194/acp-10-10875-2010, 2010.
3. Zhang X. et al. Atmosphere. 2016. 7, 158. https://doi.org/10.3390/atmos7120158.
4. Gubanova D.P. et al.  Dokl. Earth Sc. 2025. 522, 14. https://doi.org/10.1134/S1028334X25605681