Harnessing natural and mechanical airflows for surface-based atmospheric pollutant removal

Removal strategies for atmospheric pollutants are increasingly being considered to mitigate global warming and improve public health. However, the global potential of surface-based removal techniques has not yet been quantified based on limits of pollutant transport and removal rates. We evaluate the atmospheric pollutant transport to surfaces and assess the potential of surface-based removal technologies for global-scale deployment across a variety of configurations, including air interaction with the built environment, mechanical ventilation and convection systems, and over the global transportation fleet Cities provide the highest removal potential, with median annual estimates of 30 GtCO$_2$, 0.06 GtCH$_4$, 0.007 GtNO$_\text{x}$ and 0.0001 GtPM$_{2.5}$ transported to their total surface area. Cities, solar farms, HVAC systems and filters have the potential to exceed 1 GtCO$_2$/yr (1 GtCO$_2$e/yr for CH$_4$, 20-year GWP) of removal when literature-based CO$_2$-sorbent (CH$_4$-catalyst) efficiencies are applied across their total surface area. These values represent theoretical upper bounds and are intended for comparison across applications rather than application-specific deployment. HVAC filters have the potential to achieve materials costs as low as \$600 per tCO$_2$ removed (\$2000 per tCO$_2$e) when CO$_2$-sorption (CH$_4$-catalyst) technologies are incorporated into their fibre sheets and maintained through routine filter replacement, compared with \$3000 per tCO$_2$ (\$10000 per tCO$_2$e) for city surfaces, based on the literature values for these technologies' materials costs. These findings demonstrate that integrating surface-based pollutant removal technologies into infrastructure may offer a pathway to advance climate and health objectives, though further studies are needed to assess their feasibility in application, and application-implementation rates and cost.