With respect to nitrous oxide (N SB 2 sb O), NHS England, Scotland and Wales have a dedicated N SB 2 sb O programme as informed by the lean systems approach proposed by the N SB 2 sb O project [2]. NHS Lothian, the primary test site for the N SB 2 sb O system loss theory [1] has now removed its piped N SB 2 sb O systems but cannot clinically account for its turnover of portable N SB 2 sb O cylinders (28,800 l in 2021/2022). [Extracted from the article]