About

Steve Miller is an Associate Professor in the Department of Environmental Studies at the University of Colorado Boulder. He holds a Ph.D. in Environmental Science and Management from the University of California, Santa Barbara, and a B.S. in Computer Science from Stanford University. His research combines tools from computer science and economics to study the effective management of shared natural resources such as fisheries, the ways environmental policies stimulate the development and deployment of new technologies that reduce environmental impact, and the impacts of changing temperatures on natural resource use and economies. Methodologically, Steve Miller is primarily interested in how machine learning and applied statistics can be combined to answer causal questions within the environmental realm. His work involves collaboration with experts from various disciplines. Prior to his current position, he was an Assistant Professor in the University of Minnesota’s Applied Economics department and spent five years as a Product Manager at Google, where he helped launch ocean features within Google Earth. He is actively accepting students for Fall 2026 and is interested in working with students on topics related to the impact of changing temperatures on natural resources and the economy, as well as the effectiveness of environmental policies, utilizing statistical tools such as econometrics and machine learning.

Research topics

• Political Science
• Medicine
• Engineering
• Physics
• Internal medicine
• Meteorology
• Chemistry
• Sociology
• Social Science
• Environmental science
• Public relations
• Neuroscience
• Economics
• Anesthesia
• Virology
• Architectural engineering
• Natural resource economics
• Geography
• Psychology
• Atmospheric sciences
• Law
• Mechanical engineering
• Biology
• Ecology

Selected publications

• Potential airborne transmission of SARS-COV-2 through bathroom ventilation ducts associated with an outbreak in a residential building in Santander, Spain, 2020

  PLoS ONE · 2026-05-12

  articleOpen access1st authorCorresponding

  During the COVID-19 pandemic, airborne transmission of SARS-CoV-2 via respiratory aerosols was a critical concern in indoor environments. In the city of Santander, Spain, an outbreak in a multi-family residential building during a period of low community transmission revealed vertical clustering of 15 cases in four homes. The building's design included single interior bathrooms without windows in each home, ventilated by a shared vertical bathroom duct system. Field measurements, computational fluid dynamics (CFD) simulations, and multi-zone airflow modeling were performed to evaluate vertical disease transmission potential in the Santander building. Epidemiological and genetic data combined with the field-collected data and modeling indicated that the most plausible transmission route was the bathroom vertical ventilation duct system, which facilitated movement of infectious aerosol between vertically connected homes. Additionally, operating the kitchen exhaust fan can augment the movement of aerosols between occupied spaces increasing the potential for infection. Recommendations for mitigating future risks include the installation of forced air exhaust fans with non-return flaps in bathroom ducts.

  PublisherDOI

• <i>ES&amp;T</i> at 60: Science, Community, and the Facets of Impact

  Environmental Science & Technology · 2026-01-13

  article
  PublisherDOI

• Field Evaluation of Do-It-Yourself Air Filtration Solutions for Evaporative Coolers to Reduce Ambient Particle Infiltration in Homes in Wildfire-Affected Communities

  ACS ES&T Air · 2026-03-10

  articleOpen access

  Evaporative coolers (ECs) introduce outdoor air pollutants indoors when operating. This study evaluates the potential of do-it-yourself (DIY) air filtration solutions for ECs to cost-effectively reduce the infiltration of ambient fine particulate matter (PM2.5) in homes with ECs using measurements in 48 homes in wildfire-affected agricultural communities in California. All homes received one portable air cleaner (PAC); 25 homes also received DIY filters (mostly MERV 13) attached to their ECs. PurpleAir monitors measured indoor and outdoor PM2.5 concentrations. PAC operation was monitored in all of the homes. EC usage was monitored in some homes and predicted using relative humidity dynamics in all homes. Conditional analyses between EC likely on and off conditions were used to evaluate the impacts of DIY EC filters on ambient PM2.5 infiltration, including during several wildfire-affected days. Median levels of ambient PM2.5 infiltration increased ∼36–42% in homes with only PAC interventions when ECs were likely operating compared to only ∼10–11% in homes with both PACs and DIY EC filters. Pre/postintervention comparisons in a subset of homes confirmed PM2.5 infiltration reductions. EC filter performance declined after extended use. Results suggest that short-term EC filter deployments are likely a cost-effective way to mitigate wildfire smoke infiltration inside these homes.

  PublisherDOI

• Is There an Optimal Wavelength for Germicidal Ultraviolet Air Disinfection?

  Environmental Science & Technology · 2026-03-06

  articleOpen access

  Germicidal UV (GUV) disinfection is effective against airborne pathogens, but it has been recently reported to increase indoor air pollution. Conventional GUV at 254 nm is applied in the upper room only due to skin/eye safety limits, while “Far UVC” (e.g., at 222 nm) is applied across the whole room due to less restrictive safety limits, enabling simpler installation and disinfection. GUV light sources at other wavelengths are being actively developed, creating an urgent need for guidance on their relative advantages. We investigate GUV between 185 and 310 nm by modeling in search of an optimal wavelength with both high disinfection and safety. For a specific fluence rate, GUV-induced air pollution health risks are at least ∼20 times larger below 242 nm than above it. This is mainly due to O3 production through O2 photolysis below 242 nm, with a contribution from particulate matter formation from enhanced volatile organic compound oxidation. When normalized to a constant CDC-recommended disinfection rate of 5 equiv air changes per hour (eACH), pollution risk below 242 nm is also at least ∼20 times that above 242 nm. At very high disinfection rates such as 20 eACH, the difference between the ratios below and above 242 nm is smaller, but still a factor of ∼20. Our results show a clear advantage of upper-room GUV vs Far UVC for indoor air pollution. These results appear robust despite substantial uncertainties in absolute disinfection efficiencies, which are a critical limitation for widespread GUV application. Thus, there is no optimal GUV wavelength across all important criteria (exposure limits, disinfection efficiency, indoor air pollution, and logistic requirements), and these trade-offs should be considered in different situations to maximize the overall benefit. The use of Far UVC may require simultaneous deployment of air cleaning for pollution mitigation.

  PublisherDOI

• Editor’s Highlight: Six Decades of Progress, a New Era of Atmospheric Science

  Environmental Science & Technology · 2026-03-03

  article1st authorCorresponding
  PublisherDOI

• An indoor air pollution research strategy for the United Arab Emirates

  Indoor Environments · 2025-03-23 · 1 citations

  articleOpen access

  Clean indoor air is vital for health in all settings, especially in locations where extreme climates restrict outdoor activity, such as in the United Arab Emirates (UAE). UAE summer temperatures routinely exceed 42°C (108°F), discouraging outdoor activity and limiting natural ventilation of structures. Yet, little research is available on indoor air quality in the UAE. To inform the design of a new indoor air quality program, the Abu Dhabi Public Health Centre commissioned a study to characterize and prioritize knowledge gaps on indoor air quality and its relationship to health in the UAE and to identify potential partners for the program. Research gaps and priorities were identified by a panel of 16 international and local indoor air quality experts through a two-day structured, in-person workshop and follow-up survey. Key partners were identified through a stakeholder mapping exercise and e-mail survey of 79 government agencies and nongovernment organizations. The expert panel concluded that the most important short-term research need is to characterize the major sources of indoor air pollution and the most frequently occurring pollutants. The panel recommended establishing a national indoor air quality observatory encompassing a wide range of settings, including residences, schools, mosques, healthcare facilities, shopping malls, and other public spaces. Indoor air quality monitors would be permanently placed to establish baseline indoor air quality, provide data to estimate source contributions, and enable tracking of changes over time. The stakeholder mapping exercise identified ten agencies that should be involved in planning, including the Abu Dhabi Public Health Centre, Department of Health–Abu Dhabi, Environment Agency–Abu Dhabi, Abu Dhabi Department of Energy, and Emirates Public Health Association. While focused on the UAE, the methods and research priorities in this study may be useful for planning indoor air quality improvement campaigns in other high-income nations.

  PublisherDOI

• Is there an optimal wavelength for germicidal ultraviolet air disinfection?

  ChemRxiv · 2025-04-11

  preprintOpen access

  Germicidal UV (GUV) disinfection is effective against airborne pathogens, but it has been recently reported to increase indoor air pollution. Conventional GUV at 254 nm is applied in the upper room only due to skin/eye safety limits, while “Far UVC” (e.g. at 222 nm) is applied across the whole room due to less restrictive safety limits, enabling simpler installation and disinfection. We investigate GUV between 185 and 310 nm by modeling, in search of an optimal wavelength with both high disinfection and safety. For a specific fluence rate, GUV-induced air pollution health risks are at least ~20 times larger below 245 nm than above it. This is mainly due to O3 production through O2 photolysis below 245 nm, with a contribution from particulate matter formation from enhanced volatile organic compound oxidation. When normalized to a constant CDC-recommended disinfection rate of 5 equivalent air changes per hour (eACH), pollution risk below 245 nm is also at least ~20 times that above 245 nm. At very high disinfection rates such as 20 eACH, the difference between the ratios below and above 245 nm is smaller, but still a factor of ~20. Our results show a clear advantage of upper-room GUV vs. Far UVC for indoor air quality. These results appear robust despite substantial uncertainties in absolute disinfection efficiencies, which are a critical limitation for widespread GUV application. Thus, there is no optimal GUV wavelength across all important criteria (exposure limits, disinfection efficiency, indoor air quality, and logistic requirements), and these tradeoffs should be considered in different situations to maximize the overall benefit. Use of Far UVC may require simultaneous deployment of air cleaning for pollution. As new practical UV light sources at wavelengths other than 222 and 254 nm keep being developed, this study provides guidance for evaluating and selecting wavelength(s) for GUV air disinfection.

  PublisherOA PDFDOI

• Evaporative coolers and wildfire smoke exposure: a climate justice issue in hot, dry regions

  Frontiers in Public Health · 2025-02-26 · 7 citations

  articleOpen access

  Low-income families in dry regions, including in the Southwestern United States, frequently cool their homes with evaporative ("swamp") coolers (ECs). While inexpensive and energy efficient compared to central air conditioners, ECs pull unfiltered outdoor air into the home, creating a health hazard to occupants when wildfire smoke and heat events coincide. A community-engaged research project to reduce wildfire smoke in homes was conducted in California's San Joaquin Valley in homes of Spanish-speaking agricultural workers. A total of 88 study participants with ECs were asked about their level of satisfaction with their EC and their willingness to pay for air filtration. About 47% of participants reported dissatisfaction with their EC, with the most frequently reported reason being that it brings in dust and air pollution. Participants were highly satisfied with air cleaners and air filters that were offered to them free-of-charge. However, a willingness to pay analysis showed that air filtration solutions would not be adopted without significant subsidies; furthermore, air filtration would be an ongoing cost to participants due to the need to regularly replace filters. Short-term filtration solutions for EC users are feasible to implement and may reduce smoke exposure during wildfire events. Such solutions would need to be offered at low-or no-cost to reduce barriers to adoption. Longer term solutions include prioritizing homes with ECs in wildfire smoke exposed regions for replacement with air cooling technologies that provide clean air. Because ECs are disproportionately in low-income homes, addressing smoke intrusion through these devices is an environmental justice issue.

  PublisherOA PDFDOI

• The influence of glottal and respiratory factors on aerosol emission during phonation

  PLoS ONE · 2025-12-05

  articleOpen accessSenior author

  INTRODUCTION: Speech-driven aerosol generation plays a key role in airborne disease transmission, yet the physiological mechanisms remain poorly understood. Beyond vocal-fold vibration, airflow and glottal configuration may be key determinants. We tested how phonation type affects aerosol generation while accounting for ventilatory output estimated from exhaled CO₂. METHODS: Five healthy female adults (22-43 years) sustained vowels across six phonation types: modal register, glottal fry, falsetto register, forced whisper, loud modal register, and vowels preceded by/h/. Aerosol concentration and size distribution (0.1-20 µm) were measured using an aerodynamic particle sizer (APS). Laryngoscopy, conducted in a separate session, was used to estimate the normalized glottal gap during the open phase of phonation (NGG). Exhaled CO₂ range was recorded concurrently as a control for ventilatory variation across tasks. RESULTS: Phonation types that had greater ventilatory output and a larger open-phase glottal gap (e.g., forced whispering, loud modal register) produced the highest aerosol concentrations; types with less ventilatory output and smaller open-phase glottal gap (e.g., glottal fry and modal register) produced the lowest. Submicron particles (0.1-1 µm) dominated across conditions. Forced whispering exhibited a bimodal aerosol distribution, with increased emissions at both the smallest (0.1-1 µm) and largest (10-20 µm) particle sizes. Despite the assumption that vocal fold vibration is necessary for aerosol production, whispering, a voiceless sound production, generated a high concentration of particles, suggesting a primary role for airflow and glottal configuration. Normalized glottal gap was the strongest predictor of aerosol output, and CO₂ range (ventilatory output) was also positively associated. CONCLUSION: Sustained sound production can generate substantial aerosols even without vocal fold vibration. The strong association between normalized glottal gap and aerosol output indicates that airflow and glottal configuration, rather than vibration alone, are primary contributors under these task conditions.

  PublisherDOI

• Aerosol Emission During Speech: Investigating the Role of Glottal Configuration and Respiratory Effort

  medRxiv · 2025-03-17

  preprintOpen accessSenior author

  Abstract Introduction Speech-driven aerosol generation plays a key role in airborne disease transmission, yet the physiological mechanisms remain poorly understood. While prior research suggests vocal fold vibration contributes to aerosol production, airflow turbulence and glottal configuration may be stronger determinants. This study examines how the type of phonation influences aerosol generation while controlling for respiratory effort. Methods Five healthy female adults (22–43 years) sustained vowels across six phonation types: modal voicing, glottal fry, falsetto, whispered speech, loud speech, and vowels preceded by /h/. Aerosol concentration and size distribution (0.1–20 µm) were measured using an aerodynamic particle sizer (APS). Laryngoscopy quantified normalized glottal gap, and CO 2 range was recorded to control for respiratory effort. Bayesian regression models assessed relationships between phonation type, aerosol generation, and physiological predictors. Results Whispering and loud speech produced the highest aerosol concentrations, while glottal fry generated the least. Smaller aerosol particles (0.1–1 µm) were most prevalent across tasks, highlighting their potential for airborne transmission. Whispering exhibited a bimodal aerosol distribution, with increased emissions at both the smallest (0.1–1 µm) and largest (10–20 µm) particles sizes. Despite the assumption that vocal fold vibration is necessary for aerosol production, whispering, a voiceless phonation, generated the most aerosols, suggesting airflow turbulence and glottal configuration are stronger contributors. Normalized glottal gap was the strongest predictor of aerosol output, followed by CO 2 range, while harmonics-to-noise ratio had a smaller effect. Conclusion Vocal fold vibration alone is not necessary for high aerosol generation; turbulent airflow through a partially open glottis is a key driver. These findings have implications for airborne disease transmission, particularly in densely occupied environments. Future research should explore real-world speech patterns to refine strategies for minimizing respiratory particle exposure.

  PublisherOA PDFDOI

Recent grants

• RAPID: Microbial Contamination and Treatment in Residences Damaged in the Recent Colorado Flood

  NSF · $50k · 2014–2014

• SCC-IRG Track 1: Empowering Environmental Justice Communities with Smart and Connected Technology: Air and Noise Pollution, Wellbeing, and Social Relations in Times of Disruption

  NSF · $1.8M · 2020–2026

Frequent coauthors

• Donna Auguste

  University of Colorado Boulder

  37 shared

• Joseph L. Polman

  36 shared

• Tanya Ennis

  University of Colorado Boulder

  36 shared

• Nicholas Clements

  University of Colorado Boulder

  32 shared

• J. L. Jiménez

  27 shared

• Jana B. Milford

  University of Colorado Boulder

  23 shared

• Michael Hannigan

  21 shared

• Steven J. Dutton

  20 shared

Education

• PhD, Civil and Environmental Engineering

  University of California Berkeley

  1996

• MS, Operations Research and Statistics

  Claremont Graduate University

  1987

• BS, Mathematics

  Harvey Mudd College

  1986