Pressurised asthma inhalers and the environment

Pressurised asthma inhalers contribute very little to global warming

There is a lot of pressure for doctors to prescribe dry powder inhalers rather than pressurised dose inhalers – this is potentially harmful and may increase contribution to global warming. The reason for this advice is to protect the environment; however asthma inhalers contribute very little (less than 0.1%) to global warming. Furthermore, someone who cannot use a prescribed inhaler there is a risk of having an asthma attack. The downside is that treatment of asthma attacks then contribute substantially to global warming. So simply switching people from pressurised inhalers to dry powder types without ensuring they can be used correctly is potentially harmful for the environment.

There are two main kinds of inhalers

Pressurised metered dose inhalers (pMDIs) and dry powder inhalers (DPIs). The pMDIs contain propellants called Fluorinated Gasses (F-Gasses). F-gasses contribute to global warming, however the pMDIs contribute less than zero point one percent (<0.1%) of global warming potential.  Our GINA Lancet paper discusses future risks posed for people with asthma because of new regulatory proposals to limit availability of F-gasses for medical use.

There is an environmental crisis

The UK Government announcement that new oil drilling licences are being considered and last year an announcement was made on the news that a new coal mine is to be opened in the UK. However, peoples lives are potentially being threatened by recommendations to change people’s asthma inhalers ‘to save the planet’.

 Discussion to reduce use of pMDIs

There is currently a lot of discussion about the environment and the effect of the F-Gasses on the potential for global warming. These F-Gasses are used mainly for industries such as those in air conditioning and heat pumps, and a very small proportion of these gasses are used as propellants in pressurised metered dose inhalers (pMDIs) used for treating lung diseases like asthma and chronic obstructive pulmonary disease (COPD).

 Inhaled medication is essential for people with lung disease

Ensure people can use their inhaler correctly

These inhaler devices are necessary and in fact essential for controlling the symptoms of these lung diseases and for preventing attacks that can lead to hospitalisation and sometimes death. So it is essential that people are shown how to use their inhaler correctly and this cannot be done if these are switched without a face to face consultation.

 Not everyone can use all of the inhaler devices

Many people, including doctors and nurses, cannot use inhaler devices correctly. Therefore the patient’s needs should be the first consideration when changing from a pressurised inhaler to another type. As the pressurised inhalers contribute very little to global warming clinicians should think carefully before switching someone to a device they cannot or will not use.

 Many people argue that doctors should be prescribing dry powder inhalers(DPIs)

Doctors are encouraged to prescribe dry powder inhalers (DPI), instead of pMDIs.

 Lifestyle versus life-saving argument

This switch from pMDIs to DPIs is justified by statements comparing the global warming effect of a pMDI with a journey by car or aeroplane. For example see the advice from NICE, see here.

 The unintended consequences of switching people inappropriately to inhalers they cannot or don’t want to use

One of the main risks of people not using their inhaler correctly is that they may have an asthma attack/exacerbation/flare-up – which could be life threatening.

Treating asthma attacks contribute to global warming
Global warming impact of treating an asthma attack

 Treatment of asthma attacks have consequences for global warming

 The arguments for switching inhalers from pMDI to DPI do not include unintended consequences such as asthma attacks and the global warming potential resulting from their treatment.

Estimates derived from one paper :

 Example calculation of the effect of an asthma attack on the environment: (with help from Patrick Henry Gallen)*

  • Average number of days spend in hospital per asthma discharge in the UK: 3.4 (OECD 2018)
  • Number of asthma-related hospitalisations in the UK: 94.6 per 100,000 population = ~63,694 hospitalisations (OECD 2018)
  • Average CO2e for newly registered vehicles: 121.3 g/km (Department for Transportation 2015)
  • Hypothetical journey: 16.09 km/10 miles (5 miles to and from hospital)
  • Hypothetical number of journeys and visitors: 2 visitors visiting twice

Example of Global warming potential due to treating an asthma attack

  • 507.8 kg CO2e per hospitalisation
  • 32,343,813 kg CO2e / 32343.8 tonnes CO2e per year due to asthma hospitalisations in the UK

 Note that this model does not into account emissions related to a possible outpatient trip prior to hospitalisation or emissions related to inhaler usage and other devices or maintenance/manufacturing thereof (e.g. O2/nebulisers).

Further evidence of hospital care of an asthma attack and its contribution to the environmental footprint: see which concludes “The ICU generates more solid waste and Greenhouse Gasses (GHGs) per bed day than the acute care unit. With resource use and emission data, sustainability strategies can be effectively targeted and tested. Medical device and supply manufacturers should also aim to minimize direct solid waste generation.”

Choose the right inhaler for the patient

Our our GINA Lancet paper makes it clear that the patients needs must be prioritised when choosing an inhaler.

Global initiative for asthma inhaler choice figure
Inhaler selection – first ensure what is best for a patient


When considering prescribing inhalers for asthma the most important thing is to select one that the patient likes and can use properly. One of the consequences of getting this wrong is that the person may have an asthma attack which may be very serious. In addition the treatment of an asthma attack contributes adversely to global warming.

  • I was priveledged to work with Patrick on the severe asthma index of the Copenhagen Institute for Futures Studies

Asthma Admissions: Inherent Bias in favour of Hospitals & Urgent Care Centres


One of the major problems in the United Kingdom is the cost of preventable recurrent treatment for people with asthma attacks in hospitals, Accident & Emergency Departments (EDs) and Urgent Care Centres.

Commissioners actively encourage General Practitioners to reduce admissions however, it is not in the interest of the providers, simply because they will lose income. That is possibly one of the major reasons that up to 10% of adults and 15% of children and young people are readmitted or re-attend for emergency care for asthma within 6 and 12 weeks of treatment. Similarly, downward pressure on GPs to prescribe expensive preventer medication for asthma results in increased attacks and secondary care utilisation – so savings in prescribing are translated into increased unscheduled care costs.

Sadly, successive governments have failed to tackle this problem by persisting with allocation of separate  budgets to the primary & secondary care sectors. This is also due to the loss of the ‘National’ in the NHS. Instead of a centralised, long term forward plan for managing health care, we have to undergo major wasteful change every time a new Minister for Health is appointed.

It really is time for change! My suggestions:

i) Stop paying Hospitals, A&E Departments and Urgent Care Centres if patients re-attend for asthma exacerbations within 4 weeks. ii) Lets have a referendum – ‘ Politicians IN or OUT of the National Health Service’

How long does an asthma flare up take to resolve?

No one knows how long an asthma attack lasts

No one knows how long an asthma flare up lasts. Asthma flare ups are also known as asthma attacks or an asthma exacerbation. Asthma exacerbations and hospital admissions can be prevented by anti-inflammatory treatment. Well controlled asthma should not flare up.

Doctors often treat attacks for a fixed time period

No one knows how long an asthma attack takes to resolve. However health professionals often treat attacks as if they do! Most asthma guidelines recommend oral corticosteroid treatment for attacks. The UK SIGN Guideline states very clearly that these corticosteroids should be continued until the attack resolves. From my knowledge, most people are treated for attacks with fixed corticosteroid courses of 3, 5 or 7 days. How do these doctors & nurses know the attack will be over in 3, 5 or 7 days?’

Oral corticosteroids should be continued as long as an attack lasts

According to the United Kingdom (BTS/SIGN) Asthma guideline section on treatment of acute asthma attacks/ Flare ups / exacerbations:

  • In Adults: Continue prednisolone (40–50 mg daily) until recovery (minimum 5 days).
  • In Children: Treatment for up to three days is usually sufficient. But the length of course should be tailored to the number of days necessary to bring about recovery. Tapering is unnecessary unless the course of steroids exceeds 14 days.

So the key message is that oral corticosteroids should be continued until the attack is over. The excellent acute asthma section (chapter 9) in the 2019 version of the BTS/SIGN Guideline is essential reading. To download it click here.

How to tell if an asthma attack is over

It may take days or weeks for an asthma flare-up to resolve. An asthma flare up or attack is over when a person is free of symptoms. An asthma attack is not over yet If rescue reliever medication is needed. When the Peak Expiratory Flow or Spirometry has returned to the patients usual best level the attack is over. Therefore treatment for attacks should continue until the attack has resolved.

Asthma is a chronic ongoing disease – not an acute disease

Asthma is a chronic ongoing disease, nonetheless it is often treated as if it is an acute illness. The attack is usually treated very well although, surprisingly, a large majority of these people are not followed up for a review to identify and deal with any modifyable features.

An asthma flare up or attack means something has gone wrong

Someone whose asthma is appropriately treated with preventer medication, should be free of attacks, and therefore an attack signals a failure of treatment. In addition, asthma attacks are a well known risk factor for future attacks and therefore people are most vulnerable after an attack.

It follows that clinicians should aim to ensure that after asthma attacks are resolved that any modifiable factors are identified and dealt with to try and prevent another attack. Listen to my asthma podcast (second from bottom) here. This is one of the two main purpose of a post attack review.

Post asthma attack reviews

The purpose of the post attack review is:

i) to assess the progress of the current attack to determine the need for treatment. Including:

  • assessing current symptoms for example using the Asthma Control Test (ACT),
  • requirement for reliever treatment,
  • night time symptoms including waking due to asthma
  • lung function (Peak Flow or spirometry).
Peak flow chart showing when an attack was over
Peak flow chart showing resolution of an asthma attack. This woman presented for the first time with an asthma attack. I did not know what her normal peak flow was so we used a peak flow chart to inform us when it would be safe to stop her oral corticosteroids

ii) to identify modifiable risk factors causing the attack and optimise care. Modifiable risk factors include:

  • failure by doctors to prescribe controller medication (mainly inhaled corticosteroids);
  • failure by patients to refill prescriptions for controller medication,
  • excess reliever prescriptions and over-reliance by patients on these.
  • For more information on modifiable risk factors see GINA Table 2-2 and Table 11 (page 82)  in the BTS/SIGN Guideline).

More details on post attack reviews here.


Keep patients safe and reduce GP’s workload by using post attack reviews to maintain asthma control.

An asthma attack signals something needs to change. Identifying modifiable risk factors and dealing with them will reduce future attacks. This will help to prevent asthma flare ups, hospital admissions and avoidable deaths. When should post asthma attack reviews be done? Ideally before the oral corticosteroids run out or within a week. Many primary care colleagues argue that this is not feasible due to heavy worlkload. A practical solution is to simply block off one appointment every afternoon for a post asthma attack review. If not taken up by midday it could be used for another patient that day.