Simulated downwind coal combustion emissions for laboratory inhalation exposure atmospheres

Abstract

Exposure atmospheres for rodent inhalation toxicology studies were generated to enable the evaluation of biological responses to a simulated downwind coal combustion atmosphere. A composition representing a single test case of emissions components as they may exist tens to hundreds of miles from a coal-fired power plant was developed. The particulate matter (PM) was 99% sulfate (partially neutralized) and 1% ash. Sulfate was present in equimolar concentrations to sulfur dioxide (SO₂). Gaseous nitrogen species included nitrogen monoxide (NO), nitrogen dioxide (NO₂), and nitric acid (HNO₃). At the high-exposure level, the gaseous species target concentrations were 0.2 ppm SO₂, 0.6 ppm NO, 0.3 ppm NO₂, and 0.1 ppm HNO₃. The test atmosphere was produced by combining effluent from a laboratory coal combustor with sulfate generated through an evaporation–condensation generator. These atmospheres were used to conduct inhalation toxicology studies that have been previously reported.

Keywords::

• Coal
• inhalation
• metals
• sulfate

Acknowledgments

The exposure system was operated and data were collected by Mark Gauna, Chris Ynostroza, and Domonic Lees. Metal analyses were conducted by the Wisconsin State Laboratory of Hygiene. Carbonyl analysis was conducted by Daniel Grosjean and Associates, Inc. Jason Laumb at Energy and Environmental Research Center provided the coal and useful discussions. The authors also thank William Linak (EPA), Jong-Ik Yoo (EPA), and Adel Sarofim (University of Utah) for useful discussions.

Declaration of interest

The authors report no declarations of interest. This work was supported by the National Environmental Respiratory Center, which was funded by numerous industry, State, and federal sponsors, including the US Environmental Protection Agency and US Department of Energy (Office of Freedom Car and Vehicle Technologies and National Energy Technology Laboratory). This manuscript does not represent the views or policies of any sponsor.