An ultra-low global warming potential (GWP) Propellant For Metered Dose Inhalers

A breakthrough technology for metered dose inhalers (MDI).


Near-Zero GWP vs. 134a, 227ea and 152a 

Good Safety Profile 

Pre-clinical toxicity studies concluded a good safety profile for use in Metered Dose Inhalers. 

Important Global Solution

Next Generation HFO technology provides excellent solutions to the global phase-down of high-GWP HFCs under the Kigali amendment to the Montreal Protocol.


A UN class 2.2 non-flammable liquefied gas. It is classified as non-flammable according to EC A11 and ASTM E681.

Why Solstice® Air is a gamechanger for the pharmaceutical industry:

As many as 384 million people suffer from chronic obstructive pulmonary disease (COPD), a progressive respiratory disease, and 339 million children and adults suffer from asthma.1,2 Many of these patients are currently treated using pressurized metered dose inhalers (pMDIs) that use hydrofluorocarbons (HFCs) that can contribute to the global carbon footprint of respiratory care. 

Honeywell’s Solstice Air® (HFO-1234ze(E) cGMP) is an alternative technology as a medical propellant, reducing the greenhouse gas emissions of pMDIs by up to 99.9% when compared to current inhaler propellants. Solstice® Air is the only non-flammable, near-zero GWP propellant available and in clinical development today for pMDIs.     

Accelerating the Transition to Lower Greenhouse Gas Respiratory Care

Honeywell and Recipharm have joined forces to speed up the development of inhalers made with near-zero GWP propellant, Honeywell Solstice® Air. 

Honeywell Solstice® Air is an alternative to HFCs in MDI

Solstice Air is VOC-exempt per the U.S. Environmental Protection Agency (EPA) and the California Air Resource Board (CARB). 

Solstice® Air – Physical Properties:

Solstice Air’s full chemical name is trans- 1,3,3,3-tetrafluoroprop-1- ene, also known as HFO-1234ze(E). Its INCI name is tetrafluoropropene. 

Physical Properties of Solstice Air*

To download the technical datasheet or for more details on Solstice Air propellant properties, environmental properties, compatibility, stability, toxicity, storage and handling, fill the contact us form below. 

*These are just some of a mosaic of properties that must be considered in identifying a suitable propellant.

Ready to Test Solstice® Air?

Samples of Solstice Air are available for testing.  To request a sample, please complete the form below.

1 Bodkin, Henry (2019-04-08). "Asthma inhalers as bad for the environment as 180-mile car journey, health chiefs say"The TelegraphISSN 0307-1235

2 World Health Organization. The top 10 causes of death. [Online. Available at:]



*These are just some of a mosaic of properties that must be considered in identifying a suitable propellant.