Criminals convicted of convection face severe penalties which seem to have a considerable deterrent effect. Nonetheless, Brownian motion is widely practised despite being strictly prohibited by a number of municipal bye-laws.
Recent attempts by the lower classes to deploy the heavier fumes from tobacco smoke in order to displace oxygen upwards have proved laughably conterproductive. The brands of cigarette they can more readily afford are liable to combust spectactularly in the resulting enriched atmosphere, thus consuming the ill-gotten excess and restoring the natural social order.
Of course, the Scottish Parliament will change all that.
No. You can't come in (except to use the bathroom), but you can look upstairs or go downstairs to the street.