Dr Seb Gray, Paediatric Consultant at Salisbury NHS Foundation Trust & CYP Asthma Lead for Bath, North East Somerset, Swindon & Wiltshire (BSW)

Twitter: @SebJGray, email: Sebastian.Gray@nhs.net 

Asthma affects over 300 million people across the world – 12% of the population in the UK has been diagnosed with the condition. Asthma is more common in children, and in total asthma accounts for 2-3% of GP consultations, 60,000 hospital admissions and 200,000 bed days per year in the UK. It’s common knowledge that environmental factors (specifically air quality and heat) can be bad for asthma, but fewer people realise that poor asthma care can actually contribute to environmental problems and climate change. 

The environment matters to young people, who increasingly want to discuss this in my asthma clinics and so I wanted to know more about the issues involved in factoring an ‘environmental’ decision into a treatment plan. With a young person who is passionate about protecting the environment, medical professionals will need to be able to discuss the balance of environmental impact of appropriate inhaler use sensitively and openly. Limiting inhaler choice to only the most ‘environmentally friendly’ has the potential to worsen asthma control. There is a real risk that hard-lined tactics to highlight the environmental impact may shame asthmatics into reduced compliance/adherence and put their lives at risk.

I also wanted to understand why some paediatric respiratory experts have concerns that policy changes solely focussed on reducing the carbon footprint may be a step in the wrong direction.

Let’s just start by saying that this piece is absolutely NOT about restricting anyone’s access to the treatment they need! Quite the opposite in fact. Everything we do in healthcare has a carbon footprint, and it is our responsibility to try and minimise this (as we know that climate change is terrible for our health). Asthma care has had some attention recently as the treatments used do involve inhalers, some of which emit greenhouse gases. 

Before we get into the deep dive, the overall messages are that 1) inhalers are IMPORTANT and must not be stigmatised; 2) the carbon footprint of a hospital stay from poorly managed asthma is much worse than any inhaler; 3) better asthma care and prevention will naturally lead to less inhaler use, with benefits all round.

Greta Thunberg remains the face of a generation keen to reverse the inactivity of previous and current generations. I don’t think anyone could argue against the motion that the actions to halt the climate crisis haven’t done enough, and carbon sensitive prescribing will have to be part of our daily practice moving forward. There will be young people passionate about the environment, and when it comes to asthma management, 

the most ‘green’ asthma plan for your patient is the one that optimally manages their symptoms with the minimum of medication, keeping them healthy and out of hospital. 

How big is the problem?

Healthcare is responsible for about 5% of global greenhouse emissions and the NHS is the largest single healthcare provider in the world. Inhalers contribute 13% of the NHS ‘carbon footprint pie’.

Chart, sunburst chart

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Credit: Tennison et al, The Lancet https://www.thelancet.com/action/showPdf?pii=S2542-5196%2820%2930271-0

Although we no longer use inhalers containing chlorofluorocarbon (CFC) propellants (phased out since 1987), newer metered dose inhalers (pMDIs) still contain hydrofluoroalkane (HFA) propellants which are over 1000 times more potent as a greenhouse gas than carbon dioxide (CO2). The carbon footprint from inhalers is measured in carbon dioxide equivalents (CO2e); the higher the CO2e, the greater the harm to the environment.

In 2019, pMDI annual use alone in the UK accounted for 0.79 megatonnes of CO2e When you start struggling to figure out how many zeros this entails, you know it’s a lot (790,000,000,000 gCO2e if you were wondering; the equivalent emissions of 600,000 diesel cars).

So it’s unsurprising that the inhaler category has been targeted as one of the focuses for the ambitious plan for delivering a ‘Net Zero’ NHS. Under the Paris Climate Change Agreement. A ‘Net Zero’ NHS would have fantastic benefits including:

  • Improved air quality, saving >5,700 lives annually
  • More physically active population, saving 38,000 lives annually
  • Healthier diets, saving 100,000 lives annually

There are direct benefits to patients with asthma, and strong epidemiological benefits for the future. There’s no doubt we should do something, so what are the options to make asthma care greener?

Inhalers look a bit like a foot, so I’ve gone with that analogy and broken it up into 4 things you can do:

  1. Look after basic foot health
  2. Know what to do with dirty socks
  3. Change the socks 
  4. Change the footwear completely

1. Looking after basic ‘foot’ health – Back to Basics and making every contact count

The national Asthma UK survey tells us we’re not getting basic asthma care right. Over 60% of patients do not receive basic asthma care and 20% do not have an annual review. In the UK we have a relatively high age standardised asthma mortality rate compared to the rest of Europe.

We know from the SABINA (SABA use IN Asthma) study that over-use of SABA’s is associated with worse outcomes. Using more than 3 SABA inhalers per year is associated with a 20-24% increased rate of exacerbations (in patients 12 or over). Identifying these patients is key to try and optimise treatments and avoid over-reliance of SABA use, improving their clinical outcomes. Also, In very simple terms, by improving the preventer treatment, you can reduce reliance on high carbon footprint reliever treatment (and higher carbon footprint hospital admission).

It’s essential we make every patient contact count. Opportunities to optimise asthma care include:

  • Routine asthma reviews
  • Repeat prescription requests & dispensing
  • Exacerbations

When you’re seeing a young person with asthma, you should always do these things:

  • Check inhaler technique
  • Check space use and management (including cleaning)
  • Check compliance
  • Check smoking & vaping status of CYP and close contacts
  • Check other environmental factors including allergens, pets, mould, damp, air quality (indoor and outdoor)
  • Check immunisation status
  • Explore psycho-social factors in adolescents using HEADSSS
  • Diagnose and manage any co-morbities
  • Update or issue a Personal Asthma Action Plan (PAAP)

Specific QI projects addressing any of these could be fantastic – hopefully there is enough information within this piece to provide sufficient evidence of a problem. Future system-wide developments that automatically identify patients with poor asthma control do not seem far away – I welcome any AI that could help. 

Compliance is key 

Patients with better asthma control use less medication overall, and have fewer hospital admissions. (The lowest carbon footprint healthcare is the healthcare the patient doesn’t need!)

Using a Smartinhaler™ Turbu+ device with Symbicort DPI was shown to decrease greenhouse gas emissions by 50%. Most of these savings were to do with better compliance, which reduced exacerbations and associated emissions (due to reliever use and hospital admissions). 

Technology can also help with compliance – in the STAAR study, electronic adherence monitoring and reminder alarms improved adherence from 49% to 70%, with significantly fewer steroid courses and hospital admissions.

MART (Maintenance and Reliever Treatment) is likely to be the direction of travel for CYP asthma treatment. Most of the MART options are DPIs and therefore have lower carbon footprints. With younger children it’s still unclear whether the transition to MART will involve still having Salbutamol MDI back-up available, but hopefully this will become more clear as research and clinical experience evolves. One inhaler as both preventer and reliever (with no SABA routinely required) would be the environmental preference. The clinical advantage is that when patients with asthma are experiencing an exacerbation not only do they get the beta-agonist effects, but they also get more inhaled steroid which will help reduce the inflammation and tackle the exacerbation. 

It’s essential to strike the right balance in encouraging environmental consideration without making patients with asthma feel guilty for using medication that has a relatively high carbon footprint.

Poorly controlled asthma has a much worse carbon footprint than someone taking their preventer inhaler regularly.

2. Know what to do with dirty ‘socks’ – Greener disposal & recycling 

Binning inhalers is terrible for the environment! If you chuck an inhaler into a black bin bag and it goes into landfill, the greenhouse gas propellants continue leaking out. All inhalers should be returned to a pharmacy where they will be sent for incineration. Incineration breaks down the hydrofluoroalkanes into less potent greenhouse gases. 

Various schemes have been run by Pharma companies over the years but none have managed to keep them going – currently there is no nation-wide system for reusing or recycling inhalers and it’s therefore about limiting rather than eliminating the carbon footprint. 

There are incentives directed at pharmacies from the Pharmacy Quality Scheme which include training patient-facing pharmacy staff to discuss safe, environmentally friendly disposal of inhalers.

If every one of the 73 million inhalers used in the UK every year was returned rather than binned this could save 512,330 tonnes of CO2e – the equivalent of a VW Golf being driven around the world 88,606 times.

How do you know how much is left in an inhaler?

If we have to use something which has a high carbon footprint, we need to make sure it’s used as efficiently as possible with the minimum of waste. Frustratingly, it can be really hard to know when an inhaler is empty (this is also obviously a potential danger if a child is trying to use an inhaler which has run out). 

Most inhalers don’t have dose counters. Things like weighing the inhaler won’t cut it in the long run and we need methods to keep it as simple as possible. @PrasadNagakumar has a fantastic twitter thread that summarises this important issue.

Technology needs to step in here – one study found that returned inhalers had 48% of the active contents still remaining! Even when ‘finished’ there will still be some propellant left in the inhaler that would cause damage if put into landfill and slowly released.

Reusable or refillable inhalers need further research and development – but this will require Pharma to invest financially and take a conscientious ethical considerate approach to the carbon footprint of processes. It’s something they must do if they are going to reduce their carbon footprint within the industry – MDI inhalers account for 13% of AstraZeneca’s carbon emissions, even more for GSK (36%). Potential areas of future development are lower emission propellants, reusable/refillable devices, longer lasting devices, in-built monitoring technology and recycling schemes

3. Change the ‘socks’ – consider switching to a lower carbon inhaler (without switching type of inhaler)

70% of all inhalers prescribed in the UK are short acting beta agonists (SABAs) making carbon emissions three times most European countries. Salbutamol comes in a few different shapes and sizes – the most commonly prescribed is Ventolin Evohaler 100mcg®. However, other pMDIs do exist and switching to Salamol® 100 micrograms saves 16,312 gCO2e per inhaler (and is actually 4p cheaper!)

OpenPrescribing is a freely accessible website with near real-time date on prescribing patterns that can identify issues honing down to individual GP practices. Here, I’ve searched for Ventolin prescriptions by Clinical Commissioning Groups:

5,394,941 Ventolin inhalers were prescribed over a year in England. If all of these were switched to Salamol the NHS would save £215,797 and 88 million kgCO2e. You can break this down to individual GP practices and highlight outliers – just imagine how fantastic this freely available data could be to assist a QI project!

If switching brands of salbutamol, warn patients that the propellant may feel different in the mouth but assure them that it does not alter the effectiveness of the inhaler. Switching half of all inhalers in the UK to lower carbon footprint devices, would save 288,000 tonnes of CO2 per year; equivalent to taking 61,000 cars off the road.

One of the simplest solutions is to make inhaler prescriptions more efficient. Switching to fewer puffs of higher strengths halves the carbon footprint so next time you’re prescribing two puffs twice daily, check if there is a double dose and go with that.

The race is on to develop more eco-friendly propellants to lower the carbon footprint of MDI’s. The propellant HFA 152a has a much lower carbon footprint than current propellants (such as HFC-134a) in MDIs. This will be extremely useful for those where MDI use is essential (but will still be higher than DPI footprints). Pharma companies Chiesi and AstraZeneca have both announced plans to launch climate-friendlier propellants in 2025. 

This study found that transitioning current MDI use to those with more environmentally friendly propellants (HFA-152a) in paediatric patients would out-perform the MDI-to-DPI inhaler switch championed by many adult studies. 

4. Change the ‘footwear’ completely – Consider pMDI to DPI switch

Dry powder inhalers (DPIs) don’t have the greenhouse gas HFA propellants of pMDIs, and so are often presented as a ‘greener’ option. 


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Based on the above, 1 puff of a pMDI is the equivalent of driving 0.86 miles in an average car… which makes smoke come out of my ears thinking about ‘burst’ therapy!

We do seem to be pretty obsessed with prescribing pMDIs. The SABINA study found that in England, approximately 70% of inhalers are pMDIs, whereas in Sweden only 13% are pMDIs. In fact, we dwarf the rest of Europe with our pMDIs prescriptions. If the UK switched to Swedish patterns of prescribing, this would save an estimated 550,000 tCO2e. There are plenty of other studies that back up the carbon and financial savings of a pMDI to DPI switch – these are a couple of examples [NHS study] and [Netherlands study]. 

The UK Department of Environment, Food and Rural Affairs has said that our reliance on MDIs should fall from the current 70% to 25% of all inhalers prescribed, which would reduce emissions by 1.3million tCO2e annually. 

The Salford Kung Study in Asthma showed that the MDI to DPI switch could improve asthma control as well as more than halve the carbon footprint. This study was again focussed on adults and the switch group was to Ellipta DPI (fluticasone furoate/vilanterol). According to the BNF, Relvar 92/22 Ellipta costs £22 per inhaler containing 30 doses whereas the Fostair 100/6 MDI costs £29 for 120 doses, lasting twice as long based on maintenance dosing. 

man holding a green board in a rally

Switching patients from MDIs to DPIs needs time and resources to be done safely and effectively. It is estimated that £18,000-£53,000 would be required for each Primary Care Network (PCN) with a total of £21-£60 million for the whole of the NHS in England. These estimates did not take into consideration the cost of the medications so was purely focussed on the direct healthcare costs of managing the switch

As with many population-based studies, this evaluation provides an interesting broad perspective and highlights the significant resources required (or more commonly lacking). However, the transferability to children is unclear as the authors acknowledge the limitation of their “assumption that the whole of the eligible population in hypothetical PCN and England would transition”.

Dry powdered inhalers should only be used in those young people who can effectively use them. The main difference is being able to take a deep, quick ‘inhale’ breath in an effective and coordinated way (which should be checked before switching in older patients you can use the In Check Dial™ to assess. I’d argue we should be doing this more in children and young people.)

Requires slot and steady inhale (3-5 seconds)Requires quick and deep inhalation
Good for poor inspiratory flowGood for people with normal inspiratory flow
Requires spacerDoes not require a spacer
Usually no dose counterUsually has a dose counter
Need to shakeNo need to shake
Not breath actuatedBreath actuated

One big concern about switching MDIs to DPIs is how to manage exacerbations. Whilst the hope is that Single Maintenance and Reliever (SMART) regimens would lead to better control, and exacerbations can be nipped in the bud quickly, what happens if and when that doesn’t work? Getting medication to the lungs with a DPI needs an effective inhalation which might not be possible during a severe exacerbation. Using a MDI with a spacer negates the need for coordinated deep inhalation. So, should we be switching to DPIs but ALSO prescribing a MDI for these occasions just in case as suggested by some guidelines? If so, surely this increases the carbon footprint rather than reducing it?!

Are DPIs really that much better?

There’s nothing simple about the pMDI vs DPI debate! When thinking about the carbon footprint of inhalers, it’s important to consider the whole life cycle of the product, in a cradle-to-grave life cycle assessment:

When all factors are included, DPIs are worse than pMDIs for some environmental impacts – including human toxicity, marine eutrophication and fossil depletion.

Switching medications on a well-controlled patient with asthma has the potential to unsettle them and increase frequency of acute exacerbations. Acute exacerbations due to poor asthma control are costly, and not just financially. The carbon footprint of managing exacerbations has been estimated as:

  • 125kg CO2e per bed day
  • 76kg CO2e per acute outpatient appointment
  • 66kg CO2e per visit to General Practice
  • 75kg CO2e per ambulance emergency response

This study (in adults) estimated the total carbon footprint of acute asthma exacerbations as over 724,000 tCO2e per year, equivalent to the emissions of 157,000 cars. Small changes to asthma exacerbation rates could have significant impacts on carbon footprints, but costs but blanket changes cannot occur on system levels – every patient will need to have an individual assessment and shared decision about what is best for them – adults and children alike. 

It’s not just about the balance of carbon footprints; asthma still kills young people and delivering a public message that might induce guilt for using inhalers is very dangerous – it has the potential to reduce compliance, placing lives at risk.

woman holding Planet over Profit placard

Unintended consequences

Wanting to reduce the carbon footprint of inhalers generally comes from a place of altruism. However, the world is a complex place and reducing carbon emissions can have negative impacts in other ways. For example, restrictions on non-medical use of propellants were introduced to limit their carbon footprint, however this is predicted to increase the cost of pMDI’s by up to 5 times by 2025. This won’t be likely to affect NHS patients, but being conscious of asthma health globally, it could be devastating – life-saving medications could easily become unaffordable. 

In Uganda only Salbutamol pMDIs meet ‘affordability’ criteria equating to 2 days’ wages (of the lowest paid government employees) comparing to 8-10 days’ wages for a DPI. In another study comparing the costs of medications, the equivalent daily wages for a SABA inhaler and Beclomethasone inhaler were 1.3 days in Bangladesh, 2.3 days in Sri Lanka, 2.5 days in Pakistan, 5.4 days in Nepal and 9.2 days in Malawi. Good intentions can sometimes lead to perverse consequences – we need to be careful we don’t widen the gap when it comes to poverty and health outcomes.

Take Home Messages

  1. Get basic asthma care right
  2. Put children and young people at the centre of every decision
  3. Return inhalers to pharmacy for proper disposal 
  4. Consider switching inhalers only if appropriate for your patient and their current situation.

If we can do these things, the future will be a brighter shade of green.

For more information and reading:

How to reduce the carbon footprint of inhaler prescribing – Greener Practice

PrescQIPP – Bulletin 295: Inhaler Carbon Footprint

Join the Future NHS – Greener NHS Knowledge Hub

The NICE “Inhalers for asthma (patient decision aid)” which (although targeted for people aged 17 or over with asthma) has a lot of really great information that can be used for shared decision making and open discussions.

Dr Seb Gray, Paediatric Consultant at Salisbury NHS Foundation Trust & CYP Asthma Lead for Bath, North East Somerset, Swindon & Wiltshire (BSW)

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