Part I – Context
Introduction
As described in the previous chapter wildfires pose enormous threats to
human health (Reid et al., 2016b, Black et al., 2017b) and some
populations are more sensitive to health impacts from wildfires.
Pregnancy and childhood are periods of increased vulnerability to
wildfire smoke owing to physiological changes in the mother during
pregnancy and the rapid growth and development that occurs in the fetus
during gestation, during infancy and throughout childhood. The scant
literature on wildfire smoke exposure during pregnancy and childhood on
health outcomes is bolstered by more abundant research on ambient air
pollution.
Scope of chapter
The aim of this chapter is to provide an overview of the associations
between wildfire smoke on perinatal and childhood health outcomes.
Exposure assessment of wildfire smoke exposure in epidemiological
studies was primarily based on exposure to a single fire event or fine
particulate matter. Particulate matter, especially particulate matter
less than 2.5 microns in aerodynamic diameter (PM2.5) is
a component of wildfire smoke, and is frequently measured as part of
routine ambient air pollution monitoring and hence is a useful and
objective measure in epidemiological studies to assess the effect of
exposure. Therefore, much of the evidence that we discuss is based on
exposure to PM2.5 during periods of wildfire events, and
the findings that we present are borrowed from the more extensive
literature of ambient air pollution (including non-wildfire sources) and
tobacco smoke to help inform our understanding of the potential health
effects of wildfire smoke during pregnancy on adverse perinatal
outcomes. More recently, studies have included more wildfire-specific
metrics including smoke days from Hazard Mapping System or
wildfire-specific PM2.5, but so far evidence is limited.
In this chapter, we first focus on pregnancy and the unique
characteristics of the prenatal period. We present a summary of studies
of wildfire exposure in pregnancy and effects on maternal and newborn
outcomes such as low birth weight, preterm birth, birth defects, infant
mortality and mental health outcomes of the mother. We discuss various
methods used to assess exposure, ascertain outcomes and adjust for
covariates in epidemiological analyses. We discuss methodological issues
such as critical periods during pregnancy, seasonality, and co-exposures
of stress during wildfire events.
Secondly, we focus on childhood as another critical period of exposure
to wildfires. We review what is known on the effects of wildfire smoke
on child health outcomes including health-service use, respiratory
symptoms, and asthma. Finally, our chapter concludes by highlighting the
gaps in the literature and future directions for research and policy.
This area of study on wildfire exposure and health effects during
pregnancy and childhood is in a nascent stage and our knowledge in this
is expected to change drastically over the next several years.