Switching from a metered dose inhaler to a dry powder version for maintenance therapy reduces the carbon footprint of asthmatic people by more than half, according to a recent study published in Thorax. The substitution would be possible without any worsening of condition while remaining a ‘green’ option for patients. The study analysed data from a group of 4000 patients, who were managing their conditions at home. The report said that after a year, the annual CO2 emissions for each person in the ‘switch’ group were less than half those of the usual care group ie. 108 kg vs 240 kg.