At any given moment this week, it is estimated that as much as a quarter of the world’s population is in a state of lockdown, countless others are required on the frontline of fighting the spread of Covid-19, and hundreds of thousands of people are confirmed to be infected with the virus – many of which are hospitalised or requiring treatment.

Oxygen is on the frontline too, and in hot demand. Medical oxygen is being used in its most critical form in treating coronavirus patients, in the areas of respiration, incident response and life support. Right now it’s about that getting that oxygen into patients and keeping their vital functions active.

With such a spotlight on medical oxygen and questions over supply chain stability to meet current and anticipated demand, does this bring greater attention to a less utilised means of oxygen supply, onsite generation via pressure swing adsorption (PSA)?

A third way

Oxygen in the medical field has traditionally been produced centrally at the ASU(s) and then distributed in liquid form, or as a gas via cylinders, to the customer.

Both of these means, and indeed a combination of them, are commonplace in the healthcare sector and especially so during this current pandemic where significant supplemental volumes of oxygen are required and portable supply is also necessary to assist first responders and equip makeshift wards and field hospitals.

An alternative and increasingly popular means of oxygen generation exists in the medical market, however, in the form of pressure swing adsorption (PSA).

Though commercialised in the 1970s, PSA oxygen concentrators for the supply of medical gas distribution systems have grown on the worldwide market in the last 25 years in particular. As the oxygen is produced onsite, without delivery and storage, medical oxygen generators have convinced many hospitals and healthcare facilities in North America, Africa, Middle East, Asia, and in recent years Europe, that they are able to supply medical oxygen at a competitive price compared to liquid oxygen or cylinders.

Read more: An introduction to PSA medical oxygen generators

In essence, the door was certainly ajar for PSA oxygen generation in the medical market but, whilst its uptake had certainly been increasing, it had still not fully penetrated this sector. Until now? Even if onsite generation is not taken advantage of during this current crisis, or not in the order of availability required, the focus on oxygen supply will arguably have opened the door to PSA oxygen systems like never before.

Medical gases oxygen mask

So what is PSA oxygen generation?

PSA systems utilise commonly available components that can greatly reduce the initial capital required compared to the cryogenic production of oxygen, and offer the kind of mobility that address the varying requirements of the hospital and healthcare sector.

Their rise in this area has been facilitated by ‘monographs’ that deem the use of oxygen in the range of 90-96% purity acceptable.

The European Oxygen 93 monograph, for example, was published in April 2011 by the European Pharmacopeia which serves as a reference for standards throughout the pharmaceutical industry in Europe. With this development, medical oxygen produced by oxygen concentrators gained official recognition to become a real alternative to traditional methods of oxygen supply (liquid or high pressure cylinders) for European facilities.

Described as a ‘major evolution in the market’ when it was explored in detail by gasworld later that year, the monograph paved the way for onsite oxygen generation as a third means of meeting medical market demand. In simple terms, what it enabled was the delivery of 93% PSA-produced oxygen to hospital patients.

oxygen mask medical hospital

As our previous hot topic titled Understanding medical oxygen explained, medical oxygen has traditionally been required to be delivered at the highest possible purity (99% or higher) and fully certified as such to be able to be used. This is the standard to which all or most regional specifications around the world are built. What has been broadly argued – accepted in terms of these monographs – in recent years though, is that medical oxygen does not necessarily have to be delivered at such purities.

Liquid oxygen at 99% purity has many advantages, particularly so for applications like metal cutting for example, but not necessarily for medical applications. Some local authorities still require 99% purity oxygen due to old regulations, but with the acceptance of international monographs these older specifications are widely being revised to 93%. Medical Oxygen Purity Requirements as per US Pharmacopeia are 93 ± 3%, the same as per European Pharmacopeia. For British Pharmacopeia it is 94%. Oxygen produced by PSA medical oxygen generators meets these requirements.

Read more: Advances in onsite oxygen generation

The units also come with an analysis device which ensures the oxygen produced onsite is at any time, and in all respects, in total conformity with the requirements of the oxygen 93% monograph. In fact, any gas that may not be compliant with the monograph can never get through to the patient as the system would automatically switch to a back-up supply.


Onsite oxygen generators can provide a range of benefits, including:

  • Environmentally friendly supply, minimising the visits of trucks for oxygen delivery and the corresponding CO2 emissions
  • No storage of oxygen in bulk onsite requiring footprint of physical space and safety considerations
  • Competitive production costs for the user often lower than the purchase cost of oxygen refills.

Opening the door…

Thousands of hospitals throughout the world are already equipped with an on-site oxygen production line, in emerging as well as in developed countries of all continents, all backed up by the implementation of the Oxygen 93 monograph in addition to a catalogue of other standards related to medical gases and devices.


Furthermore, onsite oxygen production today has a necessary track record of many years and deployments globally to assess the safety and reliability of the system.

It could be argued that beyond 2020, when the spread of coronavirus is hopefully but a painful memory for us all, these same factors of autonomy and flexibility will be relevant against a backrdrop of possible economic recession. It was by happy coincidence that the Oxygen 93 monograph was published in 2011, a period still characterised by the fallout from the 2008/9 economic crash, and the case was made back then that in such hard economic times the ‘undisputable advantages’ of the oxygen generator lay in healthcare providers having greater autonomy and being able to better optimise their operational costs.

With many widely expecting a significant – and now possibly sustained – economic recession following the effects of coronavirus globally, the same argument might well be made. One must be realistic, however: it will not be a simple journey ahead or a completely open door. There is a reason why so many health agencies continue to lobby for 99% purity, and this will likely continue long into the future. What we do know is, there’s clearly more than one way to get oxygen into the healthcare setting.


Oxygen concentrators

It would be remiss to discuss portable, flexible and independent oxygen supply without mentioning portable oxygen concentrators (POCs).

POCs have become hugely popular with users, clinicians and providers in recent years.

When used for individuals, oxygen concentrators are considered medical devices, and have been used as such for a long time for the oxygenotherapy of patients suffering from respiratory insufficiency. When used for central oxygen supply, these systems are based on the same PSA technology as we have described above, but of course at larger scale and with more functions of control and monitoring.

Oxygen concentrators are considered as medical devices by the European directive 93/42/EEC. For this reason, manufacturers must be certified according to ISO 9001 and ISO 13485 by an authorised body.

POCs have helped to alleviate the pressures experienced by hospitals, managing to free up beds and see more people on an out-patient basis. Even the integration of gas sensor technology into portable oxygen concentrators has assisted in patient care, with individuals better able to monitor their oxygen levels. Medical oxygen suppliers, through the use of gas sensor technology, are able to remotely monitor oxygen levels and ensure hospitals do not run low on crucial supplies or medical-grade oxygen.

It is with the individual user that POCs have become so popular, with their lightness, choice and portability enabling patients to manage their condition and remain active both in the home and out and about.