Principal Investigators: Delphine Farmer and Marina Vance

Year Awarded: 2020

Institution: Colorado State University, and University of Colorado Boulder

CASA logo


The Chemical Assessment of Surface and Air (CASA) Experiment centers around using chemical and environmental perturbations to investigate the chemistry of the indoor environment. Simply put, this experiment will allow us to understand not only how outdoor air pollution influences indoor chemistry, but also what types of equilibria and chemical reactions control the air we breathe – and the surfaces we interact with in our homes and buildings.

Although we spend 90% of our lives indoors, the chemical processes constantly occurring in the air we breathe and the surfaces we touch remain poorly characterized. This project follows up on the discoveries of HOMEChem and will be a collaborative, signature field project focused on chemical transformations occurring at the indoor surface-air interface using a ‘lab in the field’ approach through chemical and building perturbations to study chemical responses in the gas, particle, and surface phases.

Wildfire smoke and other outdoor air pollutants are introduced into homes through infiltration, while everyday indoor activities, consumer and building products add compounds directly into indoor air. The fate and subsequent chemistry of these gases and particles – and the resulting surface films – influence the air we breathe and the surfaces with which we interact. The CASA study centers around understanding chemical additions, or perturbations, in the indoor environment and using these perturbations to investigate pollutant fate, molecular transformations, and surface chemistry. 

Laboratory experiments take a different approach to indoor chemistry, by probing specific chemical mechanisms. For example, the Indoor Chemical Human Emissions and Reactivity (ICHEAR) campaign and its suite of controlled chamber experiments highlighted human metabolic emissions and the role of occupants in individually influencing air composition. HOMEChem combined these approaches of realistic, uncontrolled field measurements with the scripted activities more typical of chamber studies by introducing controlled perturbations into a heavily instrumented test house. HOMEChem thus probed the chemical composition of indoor air under multiple, repeatable, perturbations representing realistic activities. The benefit of these large collaborative experiments to the field of indoor chemistry is obvious: these measurements allow the experimental and modeling CIE communities to work together to test our understanding of indoor chemical processes across multiple phases.

In order to follow the chemistry from these perturbations and answer a set of core science questions, we have recruited an array of researchers, including the research groups of Dr. Jon Abbatt (University of Toronto), Dr. Allen Goldstein (University of California Berkeley), Dr. Barbara Turpin (University of North Carolina), Dr. Rachel O’Brien (College of William & Mary), Dr. Vicki Grassian (University of California San Diego), Dr. Jesse Kroll (MIT), Drs. Paul Ziemann and Jose-Luis Jimenez (University of Colorado Boulder), Dr. Andrew Ault (University of Michigan), Dr. Krystal Pollitt (Yale University), Dr. Douglas Collins (Bucknell University), in addition to Dr. Farmer and Dr. Vance’s research groups and the NIST Indoor Air Quality and Ventilation Group (Dr. Lisa Ng and Dr. Dustin Poppendieck) at the NIST Net Zero Energy Residential Test Facility.

Photo of a house, NIST NZERTF