Fine Particle Emissions From Tropical Peat Fires Decrease Rapidly With Time Since Ignition

Abstract

Southeast Asia experiences frequent fires in fuel‐rich tropical peatlands, leading to extreme episodes of regional haze with high concentrations of fine particulate matter (PM2.5) impacting human health. In a study published recently, the first field measurements of PM2.5 emission factors for tropical peat fires showed larger emissions than from other fuel types. Here we report even higher PM2.5 emission factors, measured at newly ignited peat fires in Malaysia, suggesting that current estimates of fine particulate emissions from peat fires may be underestimated by a factor of 3 or more. In addition, we use both field and laboratory measurements of burning peat to provide the first mechanistic explanation for the high variability in PM2.5 emission factors, demonstrating that buildup of a surface ash layer causes the emissions of PM2.5 to decrease as the peat fire progresses. This finding implies that peat fires are more hazardous (in terms of aerosol emissions) when first ignited than when still burning many days later. Varying emission factors for PM2.5 also have implications for our ability to correctly model the climate and air quality impacts downwind of the peat fires. For modelers able to implement a time‐varying emission factor, we recommend an emission factor for PM2.5 from newly ignited tropical peat fires of 58 g of PM2.5 per kilogram of dry fuel consumed (g/kg), reducing exponentially at a rate of 9%/day. If the age of the fire is unknown or only a single value may be used, we recommend an average value of 24 g/kg.

Constraining the Emission of Particulate Matter From Indonesian Peatland Burning Using Continuous Observation Data

“…Journal of Geophysical Research: Atmospheres concentrations of these two categories of particulate matter could range from 6 to 35%, as estimated by comparing the PM 2.5 and PM 10 data observed in Singapore during a wildfire event ( Figure S6). The observed PM and CO ratios at Pekanbaru in 2013 and 2014 were comparable to those observed as a result of peat/peatland fires in Kalimantan in 2015 (Jayarathne et al, 2018;Stockwell et al, 2016;Wooster et al, 2018) as well as the data obtained in Selangor in Malaysia (Roulston et al, 2018). The range of PM and CO ratios also overlaps with an experimental study of Malaysian peat fires (Othman & Latif, 2013).…”

“…In addition to greenhouse gases, the peatland burning also emits particulate matter as well as its precursors (Black et al, 2016;Engling et al, 2014;Fujii et al, 2014;Gaveau et al, 2014;Huijnen et al, 2016;Iinuma et al, 2007;Jayarathne et al, 2018;Parker et al, 2016;Roulston et al, 2018;Whitburn et al, 2016;Wooster et al, than 1 K. Aerosol particles emitted by tropical peatland burning influence the cloud formation process over the region (Rosenfeld, 1999). These aerosol particles also influence the health and lives of the people living in the region (Crippa et al, 2016;Koplitz et al, 2016;Kunii et al, 2002).…”

Fires, Smoke Exposure, and Public Health: An Integrative Framework to Maximize Health Benefits From Peatland Restoration

“…Third, emissions factors of OC and BC from tropical peatland burning are uncertain. Information from new field campaigns suggests that our results may be conservative (Roulston et al, 2018;Wooster et al, 2018). Fourth, there is uncertainty in the health impacts, with our estimates based on studies in the U.S. and Europe.…”

Estimation of Metal Emissions From Tropical Peatland Burning in Indonesia by Controlled Laboratory Experiments

“…In addition, flaming of vegetation samples will also need to be investigated in the future, as the process is significantly different from smoldering. A detailed comparison of laboratory experiments and field observations will be required, as some phenomena such as filtration of PM by ash are difficult to simulate in a small‐scale laboratory experiments (Roulston et al, ). Furthermore, entrainment of mineral dust, which has been identified as an important source of PM during wildfire in other areas of the world (Schlosser et al, ; Wagner et al, ), might also play a role for the tropical peatland fire in the equatorial Asia.…”

“…In addition, flaming of vegetation samples will also need to be investigated in the future, as the process is significantly different from smoldering. A detailed comparison of laboratory experiments and field observations will be required, as some phenomena such as filtration of PM by ash are difficult to simulate in a small-scale laboratory experiments (Roulston et al, 2018). Furthermore, entrainment of Figure 7.…”