Foetal Exposure to Air Pollution and Students' Cognitive Performance: Evidence from Agricultural Fires in Brazil*
| Published date | 01 February 2024 |
| Author | Juliana Carneiro,Matthew A. Cole,Eric Strobl |
| Date | 01 February 2024 |
| DOI | http://doi.org/10.1111/obes.12579 |
OXFORD BULLETIN OF ECONOMICS AND STATISTICS, 86, 1 (2024) 0305-9049
doi: 10.1111/obes.12579
Foetal Exposure to Air Pollution and Students’
Cognitive Performance: Evidence from
Agricultural Fires in Brazil*
JULIANA CARNEIRO,† MATTHEW A. COLE‡ and ERIC STROBL§
†Department of Economics, The Social Sciences Building, University of Warwick, Coventry
CV4 7AL, UK e-mail: juliana.carneiro@warwick.ac.uk
‡Department of Economics, Birmingham Business School, University of Birmingham,
Birmingham B15 2TT, UK e-mail: m.a.cole@bham.ac.uk
§Department of Economics, University of Bern, Schanzeneckstrasse 1 A219, 3001 Bern,
Switzerland e-mail: eric.strobl@vwi.unibe.ch
Abstract
This paper examines the impact of foetal exposure to air pollution from agricultural fires
on Brazilian students’ cognitive performance later in life. We rely on comparisons across
children who were upwind and downwind of the fires while in utero to address concerns
around sorting and temporary income shocks. Our findings show that agricultural fires
increase PM2.5, resulting in significant negative effects on pupils’ scores in Portuguese
and Maths in the 5th grade through prenatal exposure. Back-of-the-envelope calculations
suggest that a 1% reduction in PM2.5from agricultural burning has the potential to increase
later life wages by 2.6%.
I. Introduction
Controlled agricultural burning is a traditional technique commonly used by farmers,
particularly in parts of the developing world, to clear fields from previous harvests and
to regenerate nutrients in the soil for the next seeding phase. There is growing evidence,
however, that the smoke from agricultural fires contributes to increasing levels of fine
particulates in the air, causing harmful health outcomes for nearby communities (Andreae
and Merlet, 2001; Zhang, Liu, and Hao, 2016;Chenet al.,2017;Laiet al.,2018; Rangel
and Vogl, 2019; He, Liu, and Zhou, 2020). Since there is also compelling evidence
that exposure to poor air quality can result in cognitive impairment (Currie, Neidell,
and Schmieder, 2009b; Sanders, 2012; Bharadwaj et al.,2017; Almond, Currie, and
Duque, 2018), the prevalence of agricultural burning in many countries suggests that
*We are grateful to Matthew Neidell, Tatyana Deryugina and Sefi Roth for their helpful feedback. We also thank
Nico Pestel and other participants of the conference EAERE June 2021, and participants of the Department of
Economics at University of Bath’s seminar colleagues for their thoughtful comments. All errors and omissions
are our own. Thanks to two anonymous referees for their constructive comments. This research has not been
funded by any external organization.
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©2023 The Authors. Oxford Bulletin of Economics and Statistics published by Oxford University and John Wiley & Sons Ltd.
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Foetal exposure to air pollution and students’ cognitive performance 157
cognitive impacts may be widespread in such rural communities. Focusing on Brazil, the
purpose of this paper is to estimate the long-run causal effects of foetal exposure to air
pollution from agricultural fires on students’ academic performance in 5th grade (aged
10) national examinations.
A growing body of research has shown the contemporaneous effects of agricultural
fires on cognitive outcomes of the elderly (Lai et al.,2018), on mortality rates (He
et al.,2020), and on students’ scores in university entrance examinations (Graff-Zivin
et al.,2020), while Rangel and Vogl (2019) examine the effects of such fires on health
at birth. However, to the best of our knowledge the effects of prenatal exposure to
air pollution from agricultural burning on pupils’ scores later in life have yet to be
examined.1Filling this gap is challenging for several reasons. First, air pollution levels
may be correlated with students’ performance since parents may choose their residence
according to the air quality of the region. Second, seasonal agricultural fires may raise
farmers’ productivity and incomes, and thus may affect students’ cognitive performance
by allowing parents to invest more in their children. Finally, sugarcane is harvested in
Brazil in the winter, hence seasonality in weather conditions and winter-related diseases
could potentially result in a spurious correlation between fires and foetal health.2
To address these challenges we follow Rangel and Vogl (2019) and interact fires with
wind direction enabling us to predict spatial variation in the dispersion of smoke without
being directly related to prenatal health or students’ scores. As such, we are capable of
causally evaluating the different cognitive outcomes of agricultural burning on pupils born
upwind and downwind of the fires. Our study contributes to the literature in three ways.
First, while Rangel and Vogl (2019) examine the short-term effects of prenatal exposure
to agricultural fires on babies’ health, we provide the first analysis of the longer term
effects (pupils’ scores in the 5th grade). Second, we focus on the effects of fire-induced
air pollution on human health and hence show the mechanism through which fires affect
health. To this end, we utilize an instrumental variable approach using counts of fires
upwind from the population centroid of the municipality in which each student attended
school, which arguably provides plausibly exogenous shocks to air pollution3. Finally,
we examine fine particulate matter (PM2.5)4, which is the main by-product of agricultural
burning and is recognized as having a stronger negative link with health and human capital
than PM10 used in previous work (Zanobetti and Schwartz, 2009).
In a similar approach to ours, He et al. (2020) use the differences between upwind
and downwind fires in China as instruments for air pollution to estimate the effects
of straw burning on mortality. Our study is also related to Graff-Zivin et al. (2020)
1Other works have investigated the prenatal exposure to air pollution on students’ performance but not in the context
of agricultural fires. For an extensive literature review (Currie et al.,2014; Almond et al.,2018).
2Although a number of studies in the medical literature show a negative effect of biomass burning on health
(Arbex et al.,2004;Canc¸ado et al.,2006;Ribeiro,2008;Uriarteet al.,2009), or its positive impact on asthma
hospitalizations (Arbex et al.,2007) in Brazil, these studies still fall short of showing a causal relation by failing to
disentangle the confounding effects of other health determinants that are also correlated with controlled fires.
3Although we have secondary data on the place of birth, we cannot merge it with our main education data set.
Therefore, we use each municipality’s population centroid where the student attended school as a plausible proxy for
municipality of birth since we calculate that 92% of students interviewed by the Educational Census in 2011 lived
in the same municipality they were born. Section IV presents more detailed explanation on this migration issue.
4PM2.5refers to fine aerosol particles with a diameter of less than or equal to 2.5 micrometres (μm) near the surface.
©2023 The Authors. Oxford Bulletin of Economics and Statistics published by Oxford University and John Wiley & Sons Ltd.
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