Trace Metals in Global Air: First Results from the GAPS and GAPS Megacities Networks

Trace metals, as constituents of ambient air, can have
impacts
on human and environmental health. The Global Atmospheric Passive
Sampling (GAPS) and GAPS Megacities (GAPS-MC) networks investigated
trace metals in the air at 51 global locations by deploying polyurethane
foam disk passive air samplers (PUF–PAS) for periods of 3–12
months. Aluminum and iron exhibited the highest concentrations in
air (x̅ = 3400 and 4630 ng/m3, respectively),
with notably elevated values at a rural site in Argentina thought
to be impacted by resuspended soil. Urban sites had the highest levels
of toxic Pb and Cd, with enrichment factors suggesting primarily anthropogenic
influences. High levels of As at rural sites were also observed. Elevated
trace metal concentrations in cities are associated with local emissions
and higher PM2.5 and PM10 concentrations. Brake
and tire wear-associated metals Sb, Cu, and Zn are significantly correlated
and elevated at urban locations relative to those at background sites.
These data demonstrate the versatility of PUF–PAS for measuring
trace metals and other particle-associated pollutants in ambient air
in a cost-effective and simple manner. The data presented here will
serve as a global baseline for assessing future changes in ambient
air associated with industrialization, urbanization, and population
growth.