Globally, close to 2.8 billion people lack access to clean cooking technology, while 1.8 billion people lack access to electricity altogether. As a means to generate energy for residential tasks, it is common in many developing countries to rely on combustion of solid fuels (wood, dung, charcoal, trash, etc.). Solid-fuel use can emit substantial amounts of particulate matter, often in close proximity to residences, creating concerns for human health and climate. A main focus of my research is in investigating the health and radiative forcing impacts of residential solid-fuel use (e.g. cooking, heating, lighting, trash fires) through a mix of modeling and field work.

Trash Fires

Open combustion of household trash is ubiquitous in many developing countries. While large-scale landfill fires sometimes garner media attention, the impacts of household-level emissions are not well understood. Combustion of trash emits particulate matter as well a variety of other, potentially toxic, chemicals (the specifics of which depend on the trash itself). My collaborators and I included an updated emissions inventory of uncontrolled combustion of domestic trash and made first estimates of climate impacts and premature mortality attributable to exposure to particulate matter. We found that approximately 270,000 adult deaths are attributed to exposure to ambient particulate matter from trash fires. With regard to climate impacts, we estimated the globally averaged direct radiative effect (interaction of particulate matter with solar radiation) to range from -40 mW m-2 to +4 mW m-2 and the indirect effect (interaction of particulate matter with clouds) to range from -4 mW m-2 to -49 mW m-2. The uncertainty range is largely due to the sensitivity to the optical properties of black and brown carbon, the emission size distribution of particulate matter, and emission mass.

Kodros, J. K., Cucinotta, R., Ridley, D. A., Wiedinmyer, C. and Pierce, J. R.: The aerosol radiative effects of uncontrolled combustion of domestic waste, Atmos. Chem. Phys., 16(11), 6771-6784, doi:10.5194/acp-16-6771-2016, 2016. Article

Kodros, J. K., Wiedinmyer, C., Ford, B., Cucinotta, R., Gan, R., Magzamen, S. and Pierce, J. R.: Global burden of mortalities due to chronic exposure to ambient PM 2.5 from open combustion of domestic waste, Environ. Res. Lett., 11(12), 124022, doi:10.1088/1748-9326/11/12/124022, 2016. Article


Using a global chemical-transport model, my colleagues and I worked to quantify the sensitivity of health and climate calculations to uncertainties in various input sources. The goal is to highlight which research areas to focus on to improve estimates of health and climate impacts. We found that the climate impacts of particulate matter from solid-fuel use range from positive to negative and are largely sensitive to the black carbon to organic aerosol emission ratio, the absorptive properties of organic aerosol (termed “brown carbon”), and assumptions on how BC is mixed with scattering particles, and the emission size distribution. Conversely, while there are still major uncertainties in global mortality estimates, the global health burden of this emission sector is substantial (we estimate 2.81 million premature deaths in 2015). The uncertainties in this estimate are largely due to uncertainties in the number of people that rely on solid-fuels and the health-response relationship.

To reduce the uncertainties in the climate and health impacts of particulate matter from solid-fuel use, our team at CSU has worked on extensive laboratory and field campaigns. Outside of Chennai, India, I contributed to a project to characterize emissions from cookstoves as well as personal and ambient exposure sampling of village members. While this work is ongoing, we hope the measurements will provide a useful constraint to model estimates.

Kodros, J. K., Scott, C. E., Farina, S. C., Lee, Y. H., L'Orange, C., Volckens, J. and Pierce, J. R.: Uncertainties in global aerosols and climate effects due to biofuel emissions, Atmos. Chem. Phys., 15(15), 8577-8596, doi:10.5194/acp-15- 8577-2015, 2015. Article

Kodros J. K., Carter, E., Brauer, M., Volckens, J., Bilsback, K. R, L'Orange, C., Johnson, M., Pierce, J. R.: Quantifying the Contribution to Uncertainty in Mortality Attributed to Household, Ambient, and Joint Exposure to PM2.5 From Residential Solid Fuel Use, GeoHealth, doi:10.1002/2017GH000115, 2018. Article

Understanding aerosol-climate impacts

In working on the climate impacts of trash fires and cookstoves, we found a number of uncertainties that would be helpful to explore further. In particular, we found the interaction of particulate matter with clouds to be strongly sensitive to aerosol size distributions. We estimated the anthropogenic indirect effect using a mass-only representation of aerosols compared to a full size-resolved aerosol microphysics model. Simulations using the full microphysics model yield a global-mean anthropogenic indirect effect of -0.87 W m-2 , while the simulations with the prescribed scheme predict -0.66 W m-2. These differences suggest that simulations using a mass-only aerosol representation are unable to capture regional and temporal variability in size-resolved aerosol number, and thus may lead to biases in the indirect effect.

A large uncertainty in the climate impact due to interaction of particulate matter with incoming solar radiation is due to the assumed mixing-state of black carbon. To constrain this uncertainty, we combined measurements of shell thickness of scattering material around a black carbon core in the Canadian arctic from the POLAR6 campaign with simulated size-resolved aerosol mass and number concentrations from a global model. We found differences in the pan-Arctic springtime direct radiative effect on the order of 0.2 W m-2.

Kodros, J. K. and Pierce, J. R.: Important global and regional differences in aerosol cloud-albedo effect estimates between simulations with and without prognostic aerosol microphysics, J. Geophys. Res. Atmos., doi:10.1002/2016JD025886, 2017. Article

Kodros, J. K. Hanna, S., Bertram, A., Leaitch, W. R., Schulz, H., Herber, A., Zanatta, M., Burkart, J., Willis, M., Abbatt, J., Pierce, J. R., Size-resolved mixing state of black carbon in the Canadian high Arctic and implications for simulated direct radiative effect, Atmos. Chem. Phys. Discuss.,, in review, 2018. Article