Emissions from peat fires, the largest fires on Earth in terms of fuel consumption,
are the dominant source of haze episodes, especially in Southeast Asia. Haze is notorious
for regional air quality deterioration, transport disruptions and respiratory and
cardiovascular health emergencies. Despite their importance, current scientific
understanding of peat fire emissions is limited, and the link to combustion dynamics has
not been extensively considered in the literature. This knowledge gap impedes the
development of mitigation strategies for peat fires. In this thesis, I investigated peat fire
emissions through a series of laboratory and field-scale experiments. In the laboratory, a
new experimental rig using advanced diagnostics was developed to quantify haze
composition, fluxes and emission factors. The series of experiments revealed the roles of
different peat soil properties (moisture content, inorganic content and bulk density) in fire
dynamics and emissions. For the first time, transient gas and particulate matter (PM)
emissions are shown to be significantly dependent on the combustion dynamics, and
moisture content was found to have the primary influence on fire dynamics and the fire
chemistry. Peat at high moisture content (160%, in dry basis) significantly reduces fire
spread rate, decreases (> 50%) carbon and NH3 emissions, and limits PM emissions (< 25
g kg-1). An increase in inorganic content decreases fire spread rate, while an increase in
bulk density delays emissions. The results also show that modified combustion efficiency
(MCE), a fire behaviour proxy widely used in remote sensing and atmospheric sciences,
fails to recognise smouldering combustion with sufficient accuracy, especially for wet peat
with moisture content >120%. In addition to the lab experiments, a novel field experiment
was carried out to quantify emissions from a tropical Indonesian peatland fire. I provide
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the first field evidence indicating that changes in weather conditions (e.g., wind, rainfall)
and the large inhomogeneity of soil properties in the field (e.g., bulk density and moisture
content) affect the heat transfer and oxygen supply of peat fires, altering the fire
dynamics, and thus introducing substantial variability into the emissions. This thesis
provides a unique and comprehensive understanding of peat fire emissions, advancing
our understanding of how haze is formed and how to mitigate against peat fire and haze.