Respondent profile

Personal air-quality measuring devices5 were used to collect ambient and household pollution conditions (Jauvion et al. 2020). The devices produce reading for several pollutants: (1) particulate matter (PM) 1, (2) PM2.5, (3) PM10, (4) nitrogen dioxide, and (5) volatile organic compounds. For ambient air pollution, typically in a central location within each PSU, air quality was measured between 09:00 and 11:00 hours and once more between 19:00 and 21:00 hours for two days: a day before and on the day of the survey, with the assumption that the ambient weather conditions remain comparable over the two days. The average of all four readings is used to calculate the final exposure to ambient air pollution. The same strategy was used to measure indoor conditions for each of the households, typically in a central room.6 The final figures used for analysis are the average of ambient-outdoor and household-indoor air pollution levels, weighted by the amount of time spent indoors or outdoors.

Based on the existing literature and WhO’s 2021 Air Quality Guidelines (AQG) (WhO 2021), the study focuses on the PM2.5 and PM10 for all subsequent analysis. To normalize the exposure levels and facilitate a more intuitive understanding, the air pollutants are expressed as the percentage above (or below) the WhO’s 2021 AQG 2021.7 A binary logistic model was used to establish correlations between physical and mental health outcomes among the respondents, as well as for the analyses of heterogeneity across the four study sites. A detailed explanation of the methods, including results interpretation, are furnished in appendix C.

This section delineates the underlying demographic and socioeconomic characteristics of the respondent pool. Figure 2.1 shows the demographic characteristics of the sample. Approximately 51 and 49 percent of the sample are represented by women and men, respectively. Elderly people older than 65 years, followed by children between 0 and 5 years, represent the smallest proportion of the study population. The largest proportion are represented by those 16 to 35 years of age. Approximately 46 percent of the respondents are married. About 39.9 percent of the respondents above the age of 5 report never attending any formal schooling, while less than 1 in 10 (8.8 percent) have completed high school education or more.

Figure 2.2 presents the activity status of respondents above 5 years of age, across each of the study sites. Around 17.8 percent of all respondents are engaged in low-skilled outdoor wage work, as day laborers, porters, and other workers at the time of the survey. The proportion of individuals engaged in low-skilled indoor work is 7 percent overall. Approximately 15.1 percent of the respondents in the sample are engaged in indoor skilled wage activities. Nearly a third of the sample (31.3 percent) are homemakers.

Socioeconomic status using relative wealth index quintiles is presented in figure 2.3. Of the 18.7 percent of the sample in the poorest quintile, the largest proportion live in areas with major construction and persistent traffic, followed by those with persistent traffic. While the trends among those in the mid quintiles (poor, mid, and rich) are mixed, the richest among the sample are from the comparator site, followed by those living in areas with brick kilns.