Background Healthy lifestyle is one of the important factors affecting individual health. How to promote residents' cognition of healthy lifestyle has become an urgent practical problem for the whole society. However, there is no residents' healthy lifestyle cognitive indexes available with consideration of carbon peaking and carbon neutrality.

Objective To construct a cognitive index system for providing effective assessment on residents' cognition of healthy lifestyle under the background of carbon peaking and carbon neutrality.

Methods Based on the health belief model, a preliminary cognitive index system of residents' healthy lifestyle under the background of carbon peaking and carbon neutrality was proposed after literature study and relevant policy review. Then three rounds of indicator importance evaluation and screening by Delphi method were conducted before the index system was finally constructed. The weights of all levels of indicators were determined using analytic hierarchy process. In addition, a self-assessment questionnaire was developed based on the index system. The questionnaire was utilized to conduct a survey among 200 residents by convenience sampling in Shenyang, Liaoning Province from November to December 2021. The survey was used to examine the reliability and validity of the indicator system.

Results The effective recovery rates of the three rounds of Delphi method were all 100%. The authority coefficient was 0.84. The Kendall's W consistency test showed good expert consistency (P<0.001). Finally, a cognitive index system of residents' healthy lifestyle under the background of carbon peaking and carbon neutrality was initially constructed, including 4 first-level indicators, 8 second-level indicators, and 35 third-level indicators. Among them, the weights of the first-level indicators were 0.4541 for practice cognition, 0.2248 for benefit and obstacle cognition, 0.1626 for action clue cognition, and 0.1585 for risk cognition, respectively. The correlation coefficients between each indicator were from 0.586 to 0.977 (P<0.01). The overall Cronbach's α coefficient was 0.95, indicating high reliability. Invited experts agreed that the entries were representative and the content validity of the constructed indicator system was good. The factor analysis also showed that the structure validity was good.

Conclusion The proposed index system for residents' cognition of healthy lifestyle show good reliability and validity, which can be used as an effective assessment tool for residents' healthy lifestyle cognition under the background of carbon peaking and carbon neutrality. It can provide a scientific and theoretical basis for promoting residents' cognition and practice of healthy lifestyle.