  The on-going COVID-19 pandemic highlights the severe health risks posed by
deep submicron sized airborne viruses and particulates in the spread of
infectious diseases. There is an urgent need for the development of efficient,
durable and reusable filters for this size range. Here we report the
realization of efficient particulate filters using nanowire-based low-density
metal foams which combine extremely large surface areas with excellent
mechanical properties. The metal foams exhibit outstanding filtration
efficiencies (>96.6%) in the PM_{0.3} regime, with potentials for further
improvement. Their mechanical stability and light weight, chemical and
radiation resistance, ease of cleaning and reuse, and recyclability further
make such metal foams promising filters for combating COVID-19 and other types
of airborne particulates.
