Anesthetic gases, nitrous oxide and refrigerants
These gases are Scope 1 emissions many hospitals never count. They are also the place where clinicians, not engineers, own the decision.
Last reviewed: November 5, 2026. Informational guidance written by Tariq Khurshaidi; see the terms of use.
Matching tools: refrigerant leaks, anesthetic gases, toolkit refrigerant sheet, toolkit anesthetic gas sheet.
Who owns it
For anesthetics and nitrous oxide, the anesthesiology department owns the clinical choice, with pharmacy supplying purchase data and facilities owning piped infrastructure. For refrigerants, the plant manager owns the asset register and the certified technician or contractor owns the work.
Data you need first
- Purchases by agent of sevoflurane, isoflurane and desflurane (bottles or volume), and nitrous oxide (cylinders and bulk deliveries) for twelve months.
- Piped nitrous oxide: manifold type, number of outlets in use, and any test records. Compare purchased quantity with the volume that could plausibly have been administered.
- A refrigerant register by asset: refrigerant type, nameplate charge, top-ups with dates and quantities, and leak inspection records.
Sequence
- Count first. Enter anesthetic and nitrous oxide purchases in the anesthetic gas calculator, and refrigerant charge and top-ups in the refrigerant calculator. Both are Scope 1 and use 100-year GWP values.
- Rank. Per unit of anesthetic delivered, desflurane has a much higher global warming potential than sevoflurane or isoflurane. The ranking tells you where a clinical review could matter most.
- Take the clinical review to the right owner. Present the figures to anesthesiology. Agent choice, flow rates and technique remain clinical decisions, supported by patient safety and clinical evidence.
- Audit piped nitrous oxide. The common finding is that far more nitrous oxide is purchased than administered, with the difference lost through pipework, manifolds and outlets. Leak-test the system, and where agreed with clinicians, decommission unused piped supply and use portable cylinders where needed.
- Keep a refrigerant register, run leak checks to the schedule your regulations require, repair leaks promptly, and record all top-ups. Top-ups are leaks.
- Plan replacements around the HFC phase-down. Check current EPA requirements under Section 608 and the AIM Act for leak repair thresholds and for the refrigerants allowed in new equipment, and prefer lower-GWP refrigerants and sealed systems within the manufacturer's and the safety code's requirements.
Worked example
A hospital loses 4% of the charge of a 2,000 lb system each year. That is 80 lb. The refrigerant calculator converts the loss to CO₂e using the selected refrigerant's GWP, and prices the lost gas, so you can compare the cost of leak repair with the cost of topping up. In the anesthetic gas calculator, enter twelve months of bottles by agent: the calculator reports each agent's tCO₂e so the largest contributor is obvious before any conversation with clinicians.
The usual failure
Engineers asking clinicians to stop using an agent, instead of showing the numbers and asking the department what is possible. Another: counting only bottles opened for anesthetics and ignoring nitrous oxide lost in piped systems. A third: treating refrigerant top-ups as routine maintenance rather than as emissions and a signal of a failing asset.