Currie and Schmieder, 2009), reduces human capital formation and affects long term human capital outcomes (Bharadwaj et al., 2017; Grineski et al., 2020; Currie et al., 2009). Moreover, these negative effects are typically worse for people in lower socio-economic backgrounds.

A small subset of the literature on negative health impacts of air pollution has focused on flaring, often in the context of unconventional oil and gas production (fracking). Cushing et al. (2020) used satellite observations of flaring from unconventional oil and gas wells in Texas, and link to administrative birth records for pregnant women residing up to 5km from a flaring site. Exposure to frequent nightly flare events was associated with 50% higher odds of preterm birth and shorter gestation compared with no exposure, with effects especially for Hispanic women. Flaring was not associated with reduced birthweight among term infants after controlling for gestational age. Hill (2018) focused more broadly on shale gas development in Pennsylvania and found lower birth weight among infants born to mothers who live close to shale gas wells but an insignificant effect on birth term. Their difference-indifferences model used mothers living within 2.5 km of a shale gas well or permit prior to drilling as a control for treatment of living in the same radius after drilling began (the counterfactual change in infant health is estimated using births prior to drilling at the same distance from the well bore location or permitted location). The risk of low birth weight increased after drilling began. Colborn et al. (2014) focused on air quality around fracking sites in a rural western Colorado area where residences and gas wells co-exist. They found concentrations of pollutants well above critical levels that are associated with lower developmental and IQ scores in prior research in urban areas.

The studies described above are for localised settings in developed countries in the context of fracking but gas flaring in developing countries is mostly in the context of conventional oil and gas production. This distinction may matter as fracking is associated with other pollutants (and other channels of impact on health) that may be less relevant for conventional oil and gas production.<sup>6</sup> Thus, it is unclear how transferrable these findings may be for the health impact of flaring from conventional oil and gas production in developing countries, especially as these countries tend to have weaker environmental regulations and less monitoring than in developed countries.

There are some studies in the Nigerian context, but they are very limited non-econometric studies. A survey of attitudes towards flaring in oil producing communities found that residents perceive gas flaring as hazardous to their health, environment, and general well-being of their community but are resigned to the continued presence of flares (Edino, Nsofor and Bombom, 2009). One case study of 600 households in six Nigerian communities (three with gas-flaring and three without) found that

> 6 Fracking involves injection of chemical additives into wells. Exposure to some of these chemicals has been associated with adverse reproductive health and developmental effects in humans [see Webb et al. 2014].

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