Politicians never use their brains, what do they know? It seems that some of the CO2 used in cartridges is collected from fermentation processes, for adult beverages for example. The CO2 comes from plant materials and the plants originally pulled it out of the air so all we do when we use the CO2 to inflate tires is to (eventually) put it back into the air. Completely carbon neutral. Other CO2 may be collected from sources that burn fossil fuels, like kilns for brick or pottery. That type of source is not carbon neutral but since "we" are only collecting it, storing it for a while, and then releasing it we are carbon neutral, we are adding no extra fossil carbon to the atmosphere above what the source was going to release anyway. As far as I have been able to tell on the web nobody burns fossil fuel for no other purpose than to make CO2 for these cartridges because that would be prohibitively expensive. The only way to make them economically is to collect CO2 from another process that was going to release it anyway. The steel in the cartridges is recyclable. Manufacturing, using, and recycling steel cylinders is not carbon neutral, but it is an efficient use of carbon since it takes a lot more carbon to refine iron ore than to recycle a steel container.

I use a floor pump at home and the seat post pump in my Dahon on the road. For my Fuji hybrid I use CO2. It just seems convenient and since flats are rare where I ride the floor pump at home does vastly more inflation work than anything I carry on the road.

So, when I pump up a tire at home with the floor pump do I release more, or less, CO2 as I exhale than the CO2 cylinder would have released??

Ken