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The three scopes of green house gas emissions

Definition of scope emissions
What are they: Scopes 1, 2 and 3 (examples)
Old red ambulance

In this article Dr Aarif Ali will explain what scope greenhouse gas emissions are.

Aarif is currently a foundation doctor at Royal Berkshire NHS Foundation Trust. His time with the anaesthetic department at UCLH during medical school inspired him to pursue an interest in environmental sustainability in healthcare.

In the context of environmental sustainability and greenhouse gas emissions, ‘scopes’ are a way of categorising the different kinds of emissions a company creates, its operations and its wider value chain.

The most widely used standard for greenhouse gas accounting and reporting, is the Greenhouse Gas Protocol. It defines three scopes of emissions:

Scope 1

The Green House Gas (GHG) emissions that a company makes directly, such as running its boilers, vehicles and anaesthetic gases. Here are some examples:

  • The anaesthetic inhalational agent, desflurane is an incredibly potent greenhouse gas. It is up to 40 times more potent than its alternative sevoflurane and has a global warming potential 2500 times greater than carbon dioxide. One hour of desflurane use is equivalent to driving 200-400 km (driving from London, England to Zoersel in Belgium), and one hour of sevoflurane use approximately 5-10km (driving from Tower Bridge, in London, to Hyde Park, in London)
  • Fossil fuels used to generate heat or electricity on site, such as natural gas and oil
  • Vehicles, which run on fossil fuels owned or operated by the healthcare facility, such as ambulances or delivery trucks.

Scope 2

Indirect emissions, for example the energy the healthcare facility buys to power medical equipment, heating and cooling, lightening etc… which is being produced on its behalf.

Scope 3

Scope 3 is the largest contributor to the NHS carbon footprint. It includes all the emissions associated, not with the healthcare facility itself, but that the organisation is indirectly responsible for. These emissions are often more difficult to quantify and involve complex supply and value chains.

  • Emissions from the production of purchased goods and services and their transportation, such as medical supplies and the manufacturing of pharmaceuticals
  • Employee commuting
  • Food and catering
  • The disposal of medical waste, incineration or landfill of materials such as sharps, contaminated gloves, and other biomedical waste.

By defining scopes in this way, organisations such as the NHS can have a more comprehensive understanding of their carbon footprint and identify areas where they can reduce emissions to mitigate their impact on the environment.

Now that we have an idea of the sorts of emissions that contribute to a health system’s carbon footprint, let’s look at some ways in which we can reduce these emissions. This is by no means an exhaustive list but should give an idea of some of the changes that can be made at local and wider levels.

Scope 1:

  • Ban the use of potent GHGs such as desflurane. NHS Scotland became the first health system in the world to ban the use of desflurane, paving the way for other countries to follow suit.
  • Procedures to be performed using techniques with a smaller carbon footprint than inhalational gases, such as total intravenous anaesthetic (TIVA) and regional anaesthesia.
  • Implement energy efficiency measures such as upgrading to high-efficiency Heating, Ventilation, and Air Conditioning (HVAC) systems, improving insulation, and installing LED lighting to reduce energy consumption.
  • Transition to alternative fuels (hybrid or electric) for hospital-owned vehicles, or adopting a fleet management program to reduce the number of vehicles needed.

Scope 2:

  • Purchase electricity from renewable sources, such as wind or solar, to reduce the emissions associated with purchased electricity.
  • Install on-site renewable energy systems, such as solar panels or wind turbines to generate electricity or heat on site.
  • Conduct energy audits to identify areas of high energy consumption and implement energy-saving measures.

Scope 3:

  • Work with suppliers to reduce the carbon footprint of the products and services purchased by the hospital, including medical equipment, pharmaceuticals, and cleaning supplies.
  • Develop programs to encourage active transportation, such as walking or cycling
  • Source food and catering locally rather than nationally
  • Implement waste reduction and recycling programs to reduce emissions associated with waste disposal.

In week 2 we will look at what some hospital trusts and the NHS in the UK are doing to address the impact of some of these emissions.


  • World Business Council for Sustainable Development, World Resources Institute. The Greenhouse Gas Protocol: a corporate accounting and reporting standard (revised edition). 2015.
  • Wyssusek K, Chan KL, Eames G, Whately Y. Greenhouse gas reduction in anaesthesia practice: a departmental environmental strategy. BMJ Open Qual. 2022 Aug;11(3): e001867. doi: 10.1136/bmjoq-2022-001867. PMID: 36002191; PMCID: PMC9413181.
  • Open Government Licence. NHS England, Delivering a net zero NHS. 2022
  • Scottish Government. Making the NHS more environmentally friendly. 2023
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