Self-rated health and perceived environmental quality in Brunei Darussalam: a cross-sectional study

Objectives This paper examines the relationship between individuals’ perceptions of environmental quality and self-rated health (SRH) after controlling for dimensions of socioeconomic, demographic and healthy lifestyle variables. Design A cross-sectional survey. Setting The survey was conducted in Belait, an oil-rich and gas-rich district in Brunei Darussalam, from 17 October to 11 November 2019 and focused on the most populated subdistricts (Kuala Belait, Seria and Liang), where 97% of the people reside. Participants A final sample of 1000 respondents aged 18 years and older were randomly selected from the population of the chosen subdistricts, with 95% CI and ±3 margin of error. Due to variable selection, only 673 respondents were available for analysis. Outcome measures SRH was dichotomised into 1 for good health and 0 otherwise. Perceptions of environmental quality included perceptions of the natural environment (air quality, marine quality, water supply, noise and olfactory pollution) and the social environment (crime). χ2 and logistic regression models were used to assess the relationship between individuals’ perceived environmental quality and SRH. Results Most respondents perceived themselves with good SRH (72%). The adjusted logistic regression shows that perceptions of air quality (OR=2.20, 95% CI 1.15 to 4.22, p=0.018) and marine resources (OR=1.84, 95% CI 1.24 to 2.74, p=0.002) in their surrounding areas were significantly associated with good SRH. However, other environmental variables were insignificantly associated with SRH. Among the control variables, healthy lifestyle and employment had positive associations with good SRH (OR=3.89, 95% CI 1.96 to 7.71, p=0.000, for exercising 3–5 times a week; OR=1.72, 95% CI 1.09 to 2.71, p=0.021, for being employed). In addition, frequent physical exercise compensated for the negative health impact of environmental pollution. Conclusions This study suggests that environmental quality has an important role in SRH. However, a healthy lifestyle measured with frequency of physical exercise seems to compensate for the adverse environmental effects on SRH.

2. Abstract. Objectives. Line 45. "...accounting for...". Do you mean "...after controlling for..."? 3. Abstract. Setting, lines 48-49. "It was conducted ...", please write "The study was conducted in ...". Please also state why Belait district was chosen. 4. Abstract. Setting, lines 49-50. Please give the dates. 5. Abstract. Participants: Line 52. Who were these 1,000 respondents? What was the total population of persons aged 18 years and over in Belait district? 6. Abstract. Outcome measures, lines54-55. Change "Perception on." to "Perception of". 7. Abstract. Outcome measures. lines 54-55. add "perceptions of natural environment..." 8. Abstract, Outcome measures. line 57. Change "model" to "models". 9. Abstract. Results. There is no need to write "p-value" Just write p=... 10. Abstract. Conclusions. Please compare SRH with some objective measure of health, if possible. Otherwise this will be a weakness of the study. 11. Article Summary. Lines 28-29. self-rated health, a subjective measure. 12. Article Summary. Lines 32-33. How is using cross-sectional survey a strength? 13. Article Summary. Lines 41-42. Another weakness is that there is no comparable measure of objective health. 14. But the greatest weakness, in the opinion of this reviewer is that there is an implicit bias in terms of subjective rating of health as well as the factors that are hypothesised to affect self-rated health. Those respondents who rate their natural and social environment as good would most likely also rate their health status as being good. Otherwise, they would see themselves as contradicting themselves. The authors should try to validate the respondents' rating of their natural and social environment with data on air and water pollution and data on crime statistics. Such data, as everyone knows are measured at aggregate levels, but they are applicable to all individuals living within that aggregate space. 15. Introduction. Lines 5-6. Please give a reference. 16. Introduction. Lines 5-6. Which SDG? 17. Introduction. Line18. Change "happen" to "happens". 18 you should say "self-rated health status." 25. Page 5 of 42, lines 38-43. Self-rated health has been used also as a part of multi-dimensional human wellbeing in Assam, India (https://www.niti.gov.in/writereaddata/files/humandevelopment/Assam_HDR_30Sep2016.pdf); in Timor-Leste (https://hdr.undp.org/en/content/national-humandevelopment-report-2018-timor-leste); and in and Australia (https://doi.org/10.1371/journal.pone.0252898). In all these studies, individuals have rated their physical and psychological health based on 5 or 6 questions. Please state, in the present study under review, how many questions were asked of the survey respondents to rate their health status. 26. Page 5 of 42. Line45-46. See the previous comment. 27. Page 7 of 42, lines 28-38. Please explain why it is important to examine the relationship between natural and social environmental qualities and SRH. 28. Page 8 of 42. Lines 39-40. Explain why the sample size was taken as 1,000. What was the total population aged 18 years and above in Belait district? 29. Page 10 of 42. Lines 20-23. "Natural environmental quality were collected...". Do you mean "Data on natural environmental quality were collected..."? 30. Page 12 of 42. Lines 8-11. With perceptions of water quality, dwelling quality and social environment quality, a score of 1 is assigned to a negative perception, whereas, for all other variables, the score of 1 is assigned to a positive perception. This might create problem in interpreting the results of logistic regression. I hope you are aware of that and interpreted the findings accordingly. 31. Page 11 of 42. Lines 40-41. "1 for male and 0 for otherwise".
Please change "otherwise" to "female", unless there was an option for other sexual orientations than male and female. 32. Page 11 of 42. Lines 47-48. Does the marital status "single" include never married, widowed and widower? Or is it just "never married"? 33.

VERSION 1 -AUTHOR RESPONSE
"Self-rated Health and Perceived Environmental Quality in Brunei Darussalam: A cross-sectional study".

General comments
This manuscript is about the influence of a combination of a set of realities and perceptions on individuals' perception of their health status. The discussions, conclusions and policy recommendations though, mostly centre on the influence of perceptions of natural and social environments on an individual's perceived health status. Self-perceived health status has been used in various studies (Paul et.al, 2015;Xiao and Barber, 2008). However, what this reviewer finds unusual is that this research has used perceived status of natural and social environments as predictors of perceived health status. The authors' justification for using perceived status of the environment is that objective measures of the environment based on actual data do not exist at the individual level. There is a difference between perception and reality. The authors should try to validate the respondents' rating of their natural and social environment with data on air and water pollution and data on crime statistics. Such data, as everyone knows are measured at aggregate levels, but they are applicable to all individuals living within that aggregate space.
The manuscript is fairly well-written, but there is a need for some editing for English expressions, particularly in the use of prepositions.
The manuscript may be considered for publication provided the authors address the comments including those via sticky note copied below. I have attached a copy of the manuscript with my sticky note comments.
Comments via sticky note: in Timor-Leste (https://hdr.undp.org/en/content/national-human-development-report-2018-timor-leste); and in and Australia (https://doi.org/10.1371/journal.pone.0252898). In all these studies, individuals have rated their physical and psychological health based on 5 or 6 questions. Please state, in the present study under review, how many questions were asked of the survey respondents to rate their health status.

Thank you very much for sharing the references. These references have been included to the text. More explanations have also been added under the method section.
26. Page 5 of 42. Line45-46. See the previous comment.
Timor Leste, one of Southeast Asian countries, has been mentioned and cited in the earlier part of this paragraph

Page 7 of 42, lines 28-38. Please explain why it is important to examine the relationship between natural and social environmental qualities and SRH.
Added more explanation 28. Page 8 of 42. Lines 39-40. Explain why the sample size was taken as 1,000. What was the total population aged 18 years and above in Belait district?
This survey interviewed 1,000 randomly selected respondents aged 18 years and above. The population aged 18 years and above in Belait was roughly about 72% based on the 2016 data (DEPS, 2018). The 1000 selected respondents were approximately about 2% of the population aged 20 years and above. Unfortunately, the age composition of Belait's population in 2019 was unavailable. This size was randomly drawn with a 95% confidence level and ±3% margin of error.
29. Page 10 of 42. Lines 20-23. "Natural environmental quality were collected...". Do you mean "Data on natural environmental quality were collected..."? Revised as suggested 30. Page 12 of 42. Lines 8-11. With perceptions of water quality, dwelling quality and social environment quality, a score of 1 is assigned to a negative perception, whereas, for all other variables, the score of 1 is assigned to a positive perception. This might create problem in interpreting the results of logistic regression. I hope you are aware of that and interpreted the findings accordingly.
Yes, we are aware of this. We don't use zero and one in the Tables, instead put the labels.
31. Page 11 of 42. Lines 40-41. "1 for male and 0 for otherwise". Please change "otherwise" to "female", unless there was an option for other sexual orientations than male and female. Thank you. We changed it to female.
32. Page 11 of 42. Lines 47-48. Does the marital status "single" include never married, widowed and widower? Or is it just "never married"?
We revised the marital status as married, ever married (divorced and widowed) and single/never married. 50. Page 17 of 42. Lines 48-51. A large proportion (28.5%) of the respondents are not in the labour force. This is surprising considering the district you have studied (Belait) is a gas and oil rich district. However, one of the reasons for not being in the labour force is bad health. Therefore, it may not be surprising to find that those who are in the labour force are much more likely to state good SRH. Agree and revised.
51. Page 18 of 42. Lines13-16. "However, the health impact of doing physical exercise once or twice, or even everyday weekly was not significantly different from those never doing any exercise". Why do you think this was so?
This may indicate that too much exercise has more detrimental effects than benefits on health. However, there is no further information related to physical exercise such as the duration of exercise. This deserves further research.