Low carbon transport interventions and health inequalities: a scoping review

Background

Strategies to reduce carbon emissions can yield co-benefits for health but also have the potential to cause unintended adverse consequences and widen inequalities. This scoping review synthesises how health inequality outcomes have been measured in studies evaluating low carbon transport interventions.

Methods

The scoping review followed JBI methodology and PRISMA-ScR guidelines. We identified studies through searches across nine databases, screened them using predefined inclusion criteria, and assessed them for eligibility and quality. We extracted data using a structured tool and synthesised narratively. We evaluated how health inequalities were measured, including whether they were a primary or secondary focus, the use of gap, gradient, or targeted approaches, and whether they reported absolute, relative, or population attributable risk measures.

Results

We identified a total of 26,422 records. Following title and abstract screening and full-text review, 31 studies were retained in the final synthesis. Of the 31 studies, most were from high-income countries (n = 28). The most common decarbonisation interventions included active travel (n = 8), low emission zones (n = 6), and vehicle electrification (n = 3). Health outcomes assessed included physical health, air quality, and quality of life. Socioeconomic (n = 21), place-based (n = 14), and race/ethnicity (n = 13) metrics were most frequently examined. Health inequalities were often treated as a secondary focus (n = 17), with limited use of robust metrics to evaluate inequality outcomes.

Conclusion

There is a lack of methodological consistency in how health inequalities are assessed in evaluations of low carbon transport interventions. Future research should prioritise equity focused approaches to ensure that the health impacts of decarbonisation are better understood.