Climate change, associated with high carbon emissions, affects the social and environmental determinants of health, including clean air, safe drinking water, sufficient food and secure shelter.1,2,3 It is expected to cause approximately 250,000 additional deaths per year between 2030 and 2050, from malnutrition, diarrhoea and heat stress, incurring direct costs between USD 2-4 billion/year by 2030.4 The UK Climate Change Act 2008 was set up with a view to reduce carbon emissions by 80% by 2050. Around 4% of the country's carbon emissions is generated by the NHS, which has an essential role in meeting the net zero targets set under the Act.5 Furthermore, the Environmental Act 2021 and Health and Care Act 2022 make the NHS legally required to reduce its greenhouse emissions by 100% by 2040, with an 80% reduction by 2028-32.5 Yet, dental service delivery under the NHS continues to be resource-intensive, making up 3% of the overall carbon footprint of the NHS in England.6,7,8

Within dental practices in England, waste management is associated with 1,493 tonnes CO2e per year9,10 or 28.6 tonnes per week, wherein one tonne is equivalent to driving 6,000 km in a diesel car. An audit of dental clinical waste composition in a mixed NHS/private dental practice in England revealed that tissues, recyclable sterile wrappings and plastic coverings from personal protective equipment, like face shields, were the most commonly disposed of items in the clinical bin.11 It has been estimated that disposal of these materials in domestic or recyclable bins in that practice would reduce up to 5 kg of clinical waste per week.11,12 Moreover, although carbon footprint per tonne of hospital waste is lowest when it is recycled (21-65 kg CO2e) and highest via high temperature incineration (1,074 kg CO2e/t),13 high temperature incineration is the still the standard way of disposing of waste generated in dental practices in the UK.14

Recent infection control guidance introduced in dentistry within Scotland, encourage, under the Health Technical Memorandum HTM 01-05, single-use instruments and consumables with frequent sterile wrapping of reusable instruments.15 However, no guidelines were introduced over appropriate disposable of residual or recyclable waste produced. Such lack of guidance in infection control protocols may weaken engagement with environmental sustainability to protect the public16,17,18 and is leading to frustration among dental professionals in relation to lack of clear practice guidance.19,20,21 In a study by Grose et al. (2016), dental professionals in a dental practice in England expressed confusion over conflicting protocols outlined in local municipal corporation and HTM 01-05.8 Thus, the decision to implement sustainable waste management practices remains at the discretion of dental professionals themselves, who rely on their own knowledge and perception of the environmental impact of dentistry.

So far, research on waste disposal in dentistry is focused on dental professionals' knowledge of climate change, sustainability and their waste management practices,14,18,22,23 as well as challenges to dental waste management due to the use of large variety of clinical dental materials and instruments that makes dental waste segregation time-consuming.8,11 However, there is lack of insight on the waste management engagement and the decision-making process of dental professionals. In order to examine this gap in knowledge, the Theory of Planned Behaviour (TPB), a social-psychological behavioural decision-making model, has been employed in this study. The model has been used successfully for over four decades to predict and explain a wide range of health behaviours, including that of health professionals.24,25,26,27 The model proposes that achieving desired behaviour depends on both the motivation to act, labelled in the model as ‘intention', and ability to act, labelled as ‘perceived behavioural control' (PBC).

The model defines key factors or variables that influence health behaviours and the relationships between them. This includes an individual's perceived threat to sickness or disease (‘perceived susceptibility'), belief of its consequence (‘perceived severity'), potential positive benefits of behavioural action (‘perceived benefits'), perceived barriers to behavioural action, exposure to factors that prompt behavioural action (‘cues to action') and confidence in the ability to succeed (‘self-efficacy') in applying the behaviour.28,29Figure 1 illustrates the relationships between these factors and the potential impact they have over intention to act, and on actual behaviour.

Theory of Planned Behaviour framework. Copyright(c) 2019 Icek Ajzen

Various psychological theories and models have attempted to explain the relationship between people's thoughts, beliefs, decisions and health behaviours. However, these models have often been critiqued as ineffective due to a lack of predictive power, unclear construct development and lack of guidelines on their application to measure behaviour or intention toward a behaviour.30 Ajzen's initial attempt at developing a behavioural model was Theory of Reasoned Action (TRA), which focused on behavioural and subjective beliefs. TPB was later evolved and extended from TRA, by adding the control beliefs, which is representative for actual control as it is expected to moderate the effect of intention on behaviour.31 The intention to perform the behaviour is considered the key determinant of behaviour in the TPB, wherein the stronger the intentions to engage in behaviour, the more likely behaviour will be performed.32

Meta-analytic reviews support the effectiveness of the TPB in explaining the variance in intentions and behaviour for various health-related behaviours.33,34 McEachan et al. (2011) reviewed over 200 studies that used the TPB to prospectively predict health-related behaviours.34 The review found that intention and PBC accounted for 19% of the variance in behaviour, and attitude, subjective norms and PBC accounted for 44% of the variance in intention. Finally, the correlation between attitudes and the behavioural intention and between PBC and behavioural intention was found to be stronger than that between subjective norms and the behavioural intention. These findings are evidence that the inclusion of control beliefs in TPB makes the model more effective in understanding behavioural intentions and predicting health-related behaviours.

TPB has been used extensively to study pro-environmental behaviours, mainly due to its usefulness in developing suitable and flexible interventions.35 While quantitative methodology is commonly used for application of TPB, it is arguably limited to predicting the intention to perform behaviour rather than predicting actual behaviour, leading to an intention-behaviour gap.36,37 The intention-behaviour gap was demonstrated by Echegaray et al. (2017) in their study on e-waste recycling in Brazil. The study revealed that while the intention to recycle was widespread, favourable views on recycling and the perceived social acceptance of recycling significantly influenced actual adoption of adequate e-waste recycling. This illustrates the need to assess variables that influence the performance of behaviour in tailoring an intervention programme for a given population. Thus, it has been suggested that TPB-based studies also benefit from the qualitative assessment of beliefs.35

Indeed, our study employs qualitative methodology to examine waste segregation, sustainable dentistry and climate change attitudes and beliefs by dental professionals in Fife, Scotland, using a TPB analysis. Notably, carbon footprint of NHS primary dental care was estimated based on data sourced from NHS Fife.7