Intended for healthcare professionals

Rapid response to:


A more sustainable NHS

BMJ 2019; 366 doi: (Published 02 August 2019) Cite this as: BMJ 2019;366:l4930

Rapid Response:

Re: A more sustainable NHS

Van Hove and Leng raise some very valuable points (BMJ 2019;366:14930) on how the healthcare sector could reduce the environmental impact of metered dose inhaler (MDI) propellants and anaesthetic gases. One tool already used by anaesthetists concerned by the impact of inhaled anaesthesia shows how, with support from the sector and the pharmaceutical industry, clinicians could realise “quick wins” on the NHS’s carbon footprint which van Hove and Leng identify.

When we buy lightbulbs, we look for A++ rating labels which indicate low energy consumption. However, when faced with pharmaceuticals there is no such rating. Although a variety of matrices exist, such as the Process Mass Intensity (the ratio of mass of raw materials to API; typically 50-150), they are rarely included in product literature for clinicians to consider.

The propellants used in MDIs – either HFA-134a (Tetraflouroethane, norflurane) or HFA-227ea (heptaflouropropane, apaflurane) – have a Global Warming Potential (GWP) 1430 and 3200 times that of CO2. The CO2 equivalence (CO2e) of a 200 actuation Ventolin Evohaler inhaler has been calculated by GSK to be around 28 kg, or 141 g/puff, and, despite the launch of their inhaler recycling scheme in 2011, by 2017, 58% of users still binned used inhalers with domestic waste.

In anaesthesia, a mobile app has been developed to help clinicians to understand the impact of regularly used gases (including sevoflurane, isoflurane and desflurane). The Anaesthesia Impact Calculator allows clinicians to calculate and compare the CO2e of inhaled anaesthesia agents and carrier gases.

To the knowledge of the Alliance, there are currently no similar apps for MDIs. Although details of the propellants are found in summaries of product characteristics, their impact is not quantified. The NICE patient self-guide leaflet addresses the CO2e of inhaler actuations and expresses it in relation to dry powder inhalers and car travelling, but it’s not clear where the figure of 500 g CO2e per actuation comes from.

To achieve the system-wide approach van Hove and Leng require, we need sector wide collaboration - including from pharmaceutical companies - to develop systems like the EU Energy Rating labels, and the Anaesthesia Impact Calculator. Doctors must be informed of the sustainability (or otherwise) of their practice at the moment of decision-making.

If they were rated today, MDIs and inhalational agents would carry red Ds and DPIs a green A++.

Dr Tom Pierce, UK Health Alliance on Climate Change

Competing interests: Tom Pierce: Environmental Advisor to the Royal College of Anaesthetists. Laurence Bourton: Communications Manager, UK Health Alliance on Climate Change (cc:

02 September 2019
J M Tom Pierce
Consultant Cardiac Anaesthetist and Intensivist
Laurence Bourton
UK Health Alliance on Climate Change, University Hospital Southampton
UKHACC, c/o BMJ Publishing Group, BMA House, Tavistock Square, London, WC1H 9JP