A5020620694- Atmospheric chemistry and aerosols
- Air Quality and Health Impacts
- Air Quality Monitoring and Forecasting
- Vehicle emissions and performance
- Atmospheric and Environmental Gas Dynamics
- Radioactivity and Radon Measurements
- Coal and Its By-products
- Heavy metals in environment
- Environmental Justice and Health Disparities
- Atmospheric Ozone and Climate
- Spectroscopy and Laser Applications
- Toxic Organic Pollutants Impact
- Isotope Analysis in Ecology
- Oil, Gas, and Environmental Issues
- Chemical and Environmental Engineering Research
- Maritime Transport Emissions and Efficiency
- Atmospheric aerosols and clouds
- Risk and Safety Analysis
- Advanced Chemical Sensor Technologies
- Wind and Air Flow Studies
- Cassava research and cyanide
- Indoor Air Quality and Microbial Exposure
- Smart Materials for Construction
- Gas Sensing Nanomaterials and Sensors
- Mercury impact and mitigation studies
Environmental Protection Agency
2017-2025
Research Triangle Park Foundation
2017-2025
Colorado State University
2013-2019
Rice University
2008-2017
Arizona State University
2009-2012
California Institute of Technology
2006
Washington University in St. Louis
2004
PurpleAir sensors, which measure particulate matter (PM), are widely used by individuals, community groups, and other organizations including state local air monitoring agencies. sensors comprise a massive global network of more than 10,000 sensors. Previous performance evaluations have typically studied limited number in small geographic areas or laboratory environments. While useful for determining sensor behavior data normalization these areas, little work has been done to understand the...
An instrument for on‐line continuous measurement of the water‐soluble organic carbon (WSOC) component aerosol particles is described and results from an urban site in St. Louis are presented. A Particle‐into‐Liquid Sampler impacts ambient particles, grown to large water droplets, onto a plate then washes them into flow purified water. The resulting liquid filtered content quantified by Total Organic Carbon analyzer providing six‐minute integral measurements with detection limit 0.1 μg C/m 3...
PurpleAir particulate matter (PM) sensors are increasingly used in the United States and other countries for real-time air quality information, particularly during wildfire smoke episodes. Uncorrected data can be biased may exhibit a nonlinear response at extreme concentrations (>300 µg/m3). This bias nonlinearity result disagreement with traditional ambient monitoring network, leading to public’s confusion These must evaluated smoke-impacted times then corrected bias, ensure that accurate...
PurpleAir sensors are widely used to measure PM 2.5 levels in cities around the world. However, little is known about change sensor performance over time. This paper fills this gap.
The US Environmental Protection Agency (EPA) and other federal agencies face a number of challenges in interpreting reconciling short-duration (seconds to minutes) readings from mobile handheld air sensors with the longer duration averages (hours days) associated National Ambient Air Quality Standards (NAAQS) for criteria pollutants-particulate matter (PM), ozone, carbon monoxide, lead, nitrogen oxides, sulfur oxides. Similar issues are equally relevant hazardous pollutants (HAPs) where...
Air sensors can provide valuable non-regulatory and supplemental data as they be affordably deployed in large numbers stationed remote areas far away from regulatory air monitoring stations. have inherent limitations that are critical to understand before collecting interpreting the data. Many of these mechanistic nature, which will require technological advances. However, there documented quality assurance (QA) methods promote quality. These include laboratory field evaluation...
Unconventional oil and natural gas (UONG) exploration production have grown rapidly are expected to increase further in the United States internationally. Direct measurements of key air pollutant emissions from UONG limited, especially during drilling completion (hydraulic fracturing flowback) new wells. Knowledge emission rates (ERs) toxics other pollutants these activities is urgently needed inform public policy. To address this knowledge gap, we use a tracer ratio method quantify...
From July 2019 to January 2021, six models of PM2.5 air sensors were operated at seven quality monitoring sites across the U.S. in Arizona, Colorado, Delaware, Georgia, North Carolina, Oklahoma, and Wisconsin. Common PM sensor data issues identified, including repeat zero measurements, false high outliers, baseline shift, varied relationships between monitor, relative humidity (RH) influences. While these are often easy identify during colocation, they more challenging or correct deployment...
The Desert Southwest Coarse Particulate Matter Study was undertaken to further our understanding of ambient concentrations and the composition fine coarse particles in rural, arid environments. Sampling conducted Pinal County, Arizona between February 2009 2010. goals this study were to: (1) chemically characterize fraction particulate matter terms mass, ions, elements, bulk organic elemental carbon; (2) examine temporal spatial variability within area using a series three sampling locations...
Abstract. PurpleAir sensors which measure particulate matter (PM) are widely used by individuals, community groups, and other organizations including state local air monitoring agencies. comprise a massive global network of more than 10,000 sensors. Previous performance evaluations have typically studied limited number in small geographic areas or laboratory environments. While useful for determining sensor behavior data normalization these areas, little work has been done to understand the...
The use of air sensor technology is increasing worldwide for a variety applications, however, with significant variability in data quality. United States Environmental Protection Agency held workshop July 2019 to deliberate possible performance targets sensors measuring particles aerodynamic diameters 10 μm or less (PM
ABSTRACT Phoenix, AZ, experiences high particulate matter (PM) episodes, especially in the wintertime. The spatial variation of PM concentrations and resulting differences exposure is particular concern. In this study, PM2.5 (PM with aerodynamic diameter <2.5 μm) PM10 <10 samples were collected simultaneously from east west sides South Phoenix at a control site Tempe analyzed for trace elements bulk elemental organic carbon. Measurements showed that although had similar trends temporal scale...
• Examples of significant variability in collocated low cost replicate sensor response were shown for a PM and tVOC device. Environmental factors such as RH temperature to influence the response. Factors influencing all individual deviations examples could not be identified. End users are encouraged carefully examine data quality.
As part of the Desert Southwest Coarse Particulate Matter Study which characterized composition fine and coarse particulate matter in Pinal County, AZ during 2010–2011, several source samples were collected from different soil types to assist apportionment analysis study results. Soil included native desert soils, agricultural soils (crop farming), dirt-road material adjacent areas, paved road dusts, dirt within a cattle feedlot, an active feedlot. Following laboratory resuspension soil,...
A year-long study was conducted in Pinal County, AZ, to characterize coarse (2.5 - 10 microm aerodynamic diameter, AD) and fine (< 2.5 particulate matter (PMc PMf, respectively) further understand spatial temporal variations ambient PM concentrations composition rural, arid environments. Measurements of PMc PMf mass, ions, elements, carbon at one-in-six day resolution were obtained three sites within the region. Results from summer 2009 specifically local monsoon period are presented. The...
Fog acts as a reservoir and transport vector for chemicals in the atmosphere, altering distribution of species between gas particle phases, allowing deposition nutrients pollutants onto ecosystems crops. water trace samples were collected from Casitas Pass along Santa Barbara Channel June 2015 to identify emissions sources aqueous processes impacting Southern California air. composition was dominated by NH4+ (volume weighted mean, VWM = 232 µM, range 85–640 µM), with lesser contributions...