sounds very questionable. this line:
> Although only small, this device claims to have the same benefit of up to 275 real trees by filtering the air of up to 240 tonnes (265 tons) of carbon dioxide per year
Note that it isn't saying it removes 265 tons of CO2. That would require 265 tons of matter to be removed from the site. It says it *filters* 265 tons, saying nothing about the efficiency of removal of any particulate.
There's no way this moss would be as efficient at certain processes as a small forest. For one, the forest is simply going to produce more biomass, which means more CO2 is removed. The amount of CO2 removed from the air is directly proportional to the mass of the tree or moss added. As for other pollutants, that would require a ton of testing that has not been done.
Absorption is a function of surface area. By using moss and other algae’s that love CO2 and arranging them in a 3D space you can get about as much absorbing surface area as a small forest (in equivalent CO2 exchange capacity).
Same way catalysts, or activated carbon work, reactions need space to happen, so the more space you have (in any direction) the easier reactions are.