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Of the main routes of exposure to environmental contaminants (dermal contact, ingestion, inhalation), inhalation is of the most concern to human health because we cannot control what we breathe as well as what we touch or eat. In fact, we are still discovering ways in which the inhalation of air pollutants (especially aerosols) affects health. We now know that air pollution  millions of lives per year. Beyond that, we are curious about chronic, low-dose exposure levels  that may be linked to conditions that we are still discovering. For example, exposure to PM2.5 (particulate matter < 2.5 micrometers) has been recently tied to mental health issues, such as  and . 

We are interested in using engineering concepts to characterize emissions of aerosols (small particle or droplets suspended in air) from everyday sources and their subsequent transformations indoors and outdoors. These measurements can aid in developing tools and strategies to control emissions and minimize exposures, especially to vulnerable populations—such as children and the elderly, and incidentally exposed populations (i.e., bystanders of a certain activity). Applications of our research include evaluating physical and chemical transformations of aerosols indoors and outdoors and assessing emissions to inform "safer by design" consumer products. Our mission is to perform research that will lead to positive impact in human health and the environment. 

Main research topics:

• Formation, transport, and fate of aerosols, ranging from ultrafine (<100 nm), fine (< 2.5 µm), to coarse (>2.5 µm).
• Physical and chemical characterization of particulate matter using single-particle techniques, such as electron microscopy.
• Evaluation and use of low-cost sensors for air pollution measurements indoors and outdoors.
• Assessment and minimization of people's exposure to environmental contaminants.
• Ambient and source aerosol sampling and characterization.

Some current and past projects:

• Fulbright US Scholar: Assessment of Particulate Matter Concentrations in Java, Indonesia Using Low-Cost Fixed and Mobile Sensors: Implications for Local Air Quality Monitoring.
• : Assessing the Transport of Wildfire-Generated Particulate Matter Into Homes and Developing Practical Interventions to Reduce Human Exposure (WildPM). Project Description Page.
• NSF CAREER: Physical transformations of aerosols after transport between indoor and outdoor environments.
• : Chemical Assessment of Surfaces and Air (funded by the Alfred P. Sloan Foundation).
• : A collaborative indoor air chemistry field study (funded by the Alfred P. Sloan Foundation).
• of novel and homemade masks and respirators (funded by NREL; completed).
• Home sensors: Evaluating the use of low-cost particulate matter sensors in home applications.
• .
• : A community of researchers in the chemistry of indoor environments (funded by the Alfred P. Sloan Foundation).
• the impacts of air pollution and weathering on the efficiency of photovoltaic systems (a collaboration with Prof. Mike Hannigan and Dr. Mike Deceglie at NREL, funded by NREL; completed).
• Emissions of ultrafine aerosols .

Past projects (before joining CU Boulder):

• : The Virginia Tech National Center for Earth and Environmental Nanotechnology Infrastructure (project ongoing, my participation ended in 2016).
• Characterization of in the city of Shanghai, China (2014 - 2016).
• Keeping track of nanotechnology in the real world: Redeveloping the Wilson Center’s  (2013 - 2015).
• Children's exposure to silver nanoparticles in   (2010 - 2012).
• Consumer exposure to silver nanoparticles in  (2008 - 2012).
• : Atmospheric Studies in the US-Mexico Border Region (2010).
• Indoor air quality  (2007 - 2008).
• Development of methods for sampling and characterizing odorous air samples (2003 - 2008).
• and impact assessment of  (2003 - 2008).

Some of our Laboratory Instrumentation

• TSI Scanning Mobility Particle Sizer (SMPS) systems, including a 1-nm SMPS, nano DMA, and long DMA.
• TSI Nanoscan portable SMPS system + Optical Particle Sizer (OPS) for size distributions 12 - 10,000 nm.
• Kanomax Aerosol Particle Mass Analyzer.
• TSI laser photometer.
• Aethlabs 5-wavelength aethalometers.
• Thermodenuder.
• Atomizers and other aerosol generators.
• Table-top chambers.
• A 38 cubic meter aerosol emissions evaluation room, separate from the building's HVAC system, with a independent 30 ACH flushing system.
• Access to GC-MS, ICP-MS, transmission and scanning electron microscopy, and other shared facilities.