Ralph J. Delfino

picture of Ralph J. Delfino

Professor, Epidemiology
School of Medicine
Vice Chair, Research and Graduate Studies, Epidemiology
School of Medicine
Associate Director, Genetic Epidemiology Research Institute

M.D., University of Chicago, 1987, Medicine

Ph.D., McGill University, 1993, Epidemiology and Biostatistics

Phone: (949) 824-1767
Fax: (949) 824-1343
Email: rdelfino@uci.edu

University of California, Irvine
224 Irvine Hall
Mail Code: 7555
Irvine, CA 92697
Research Interests
Environmental epidemiology; air pollution health effects; chronic disease epidemiology; gene-environment interactions
Academic Distinctions
Dr. Delfino has served on several external scientific advisory committees for environmental health research centers at major universities, and was invited by the Office of Research at the University of California Office of the President (UCOP), to serve on the California Air Resources Board's Air Quality Advisory Committee during 2004-2006. He has served on the Environmental and Occupational Program Committee, American Thoracic Society International Conferences, serves as a reviewer for prestigious journals, is a member of Editorial Review Board, Environmental Health Perspectives, and has served as a proposal reviewer for several NIH study panels.
Research Abstract
My research and teaching focus is in environmental epidemiology. My studies have been designed to evaluate the relation of health outcomes to well-characterized air pollution exposures in potentially susceptible populations. My research group has evaluated multiple clinical, biological and genetic factors to understand the effects of air pollutants on respiratory health, cardiovascular function, oxidative stress, and airway and systemic inflammation. This is being accomplished, in part, with cohort panel studies that involve repeated measures of exposures and outcomes in subjects. Major efforts of this research are to obtain accurate and near real-time exposure measurements across the everyday life of people.

Study designs have involved following cohorts of subjects with asthma for several months, and making field assessments of lung function, and exhaled nitric oxide as a marker of airway inflammation. The asthma studies and other ongoing work employ electronic diaries and data loggers to monitor medication use, symptoms, spatial location, and physical activity. Similarly, for studies of cardiovascular health, panels of subjects with coronary artery disease have been followed with ambulatory electrocardiograph and hourly blood pressure monitoring, and with repeated blood draws for circulating biomarkers of inflammation, thrombosis, and oxidative stress. For both studies of asthma and cardiovascular outcomes, pollutants linked to traffic emissions and photochemically-related pollutants have been associated with health outcomes.

Current research is to explore the effects of air pollutant exposures on leukocyte gene expression in several key biological pathways including NF-kB activation, cytokine and chemokine-mediated signaling, coagulation, Nrf2/ARE-mediated oxidative stress response, and xenobiotic metabolism. I am also evaluating whether polymorphisms in genes involved in oxidative stress and other responses modify associations between air pollutants and health outcomes. Major ongoing research efforts are to better characterize the pollutant chemicals and particle oxidative potential that are responsible for exposure-response relations, and to evaluate the health effects of combustion-generated nanoparticles from traffic sources as compared with larger particles that dominate US EPA-regulated ambient particle mass.

Overall, my findings are generating new data on susceptibility to the adverse effects of air pollutants and the role that toxic pollutants in urban air play in respiratory and cardiovascular health.
Delfino RJ, Becklake MR, Hanley J. The relationship of urgent hospital admissions for respiratory illnesses to photochemical air pollution levels in Montreal. Environ Res, 1994; 67:1-19.
Delfino RJ, Coate B, Zeiger RS, Seltzer JM, Street DH, Koutrakis P. Daily asthma severity in relation to personal ozone exposure and outdoor fungal spores. Am J Respir Crit Care Med, 1996; 154:633-41.
Delfino RJ, Murphy AM, Burnett RT, Brook JR, Becklake MR. Effects of ozone and particulate air pollution on emergency room visits for respiratory illnesses in Montreal. Am J Respir Crit Care Med, 1997; 155:568-576.
Liu L-J S, Delfino RJ, Koutrakis P. Ozone exposure assessment in a southern California community. Environ Health Perspect, 1997; 105:58-65.
Delfino RJ, Zeiger RS, Seltzer JM, Street DH, Matteucci RM, Anderson PR, Koutrakis P. The effect of outdoor fungal spore concentrations on asthma severity. Environ Health Perspect 1997; 105:622-35.
Delfino RJ, Murphy-Moulton AM, Becklake MR. Emergency room visits for respiratory illnesses among the elderly in Montreal: Association with low level ozone exposure. Environ Res, 1998; 76:67-77.
Delfino RJ, Zeiger RS, Seltzer JM, Street DH. Symptoms in pediatric asthmatics and air pollution: Differences in effects by symptom severity, anti-inflammatory medication use, and particulate averaging time. Environ Health Perspect, 1998; 106: 751-61.
Quintana PJE, Valenzia JR, Delfino, RJ, Liu L?J S. Monitoring of 1-minute personal particulate matter exposures in relation to voice-recorded time-activity data. Environmental Research, 2001; 87:199-213.
Delfino RJ, Zeiger RS, Seltzer JM, Street DH, McLaren, C. Association of asthma symptoms with peak particulate air pollution and effect modification by anti-inflammatory medication use. Environ Health Perspect, 2002; 110:A607-A617.
Delfino RJ. Epidemiological evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research. Environ Health Perspect, 2002 110(Suppl 4):573-589.
Delfino RJ, Gong H Jr, Hu Y, Pellizzari ED, Linn WS, Avila M. Relationship of symptoms and peak expiratory flow in asthmatic children to exhaled breath and ambient VOCs in a Hispanic community with high traffic density. J Expo Analysis Environ Epidemiol 2003; 13:348-63.
Delfino RJ, Gong H Jr, Hu Y, Pellizzari ED, Linn WS, Avila M. Effects of ambient VOCs and criteria gases on symptoms in asthmatic children living in a Hispanic community with high traffic density. Environ Health Perspect 2003; 111:647-656.
Chakrabarti B, Fine PM, Delfino RJ, Sioutas C. Performance evaluation of the active-flow personal DataRAM PM2.5 mass monitor (Thermo Anderson pDR-1200) designed for continuous personal exposure measurements. Atmos Environ 2004; 38:3329-40.
Quintana PJE, Delfino RJ, Korrick S, Ziogas A, Kutz FW, Jones EL, Laden F, Garshick E. Adipose tissue levels of organochlorine pesticides and PCBs and risk of non-Hodgkin’s lymphoma. Environ Health Perspect 2004; 112:854-61.
Delfino RJ, Quintana PJE, Floro J, Gastañaga VM, Samimi BS, Kleinman MT, Liu L-JS, Bufalino C, Wu C-F, McLaren CE. Association of FEV1 in asthmatic children with personal and microenvironmental exposure to airborne particulate matter. Environ Health Perspect 2004; 112:932-41.
Wu CF, Delfino RJ, Floro JN, Samimi BS, Quintana PJE, Kleinman MT, Liu L-JS. Evaluation and quality control of personal nephelometers in indoor, outdoor and personal environments. J Expo Analysis Environ Epidemiol 2005;15:99-110.
Wu CF, Delfino RJ, Floro JN, Quintana PJE, Samimi BS, Kleinman MT, Allen RW, Liu L-JS. Exposure assessment and modeling of particulate matter for asthmatic children using personal nephelometers. Atmos Environ 2005; 39:3457-69.
Staimer N, Delfino RJ, Sioutas C, Bufalino C, Fine PM, Meacher D, Tjoa T, Kleinman MT. Evaluation of an active personal exposure monitor for NO2. Anal Bioanal Chem 2005; 383:955-62.
Sioutas C, Delfino RJ, Singh M. Exposure assessment for atmospheric ultrafine particles (UFP) and implications in epidemiological research. Environ Health Perspect, 2005; 113: 947-55.
Delfino RJ, Sioutas C, Malik S, Potential role of ultrafine particles in associations between airborne particle mass and cardiovascular health. Environ Health Perspect, 2005; 113: 934-946.
Arhami M, Kuhn T, Fine PM, Delfino RJ, Sioutas C. Effects of sampling artifacts and operating parameters on the performance of a semi-continuous particulate EC/OC monitor. Environ Sci Technol 2006; 40:945-53.
Delfino RD. Who are the children most susceptible to air pollution? Am J Respir Crit Care Med, 2006 15;173:1054-5.
Wu J, Winer A, Delfino R. Exposure assessment of particulate matter air pollution before, during, and after the 2003 southern California wildfires. Atmos Environ, 2006; 40: 3333-3348.
Thompson R, Delfino RJ, Tjoa T, Nussbaum E, Cooper D. Evaluation of daily home spirometry for school children with asthma: new insights. Pediatr Pulmonol, 2006; 41:819-28.
Delfino RJ. Think globally, breath locally: Why the worldwide health impact of air pollution on young children begins in our neighborhoods. Thorax, 2006; 61:184-185.
Schwindt CD, Tjoa T, Floro J, McLaren CM, Delfino RJ. Association of atopy to asthma severity and medication use in children. J Asthma, 2006; 43:439–446.
Gastañaga VM, McLaren CE, Delfino RJ. Power calculations for generalized linear models in observational longitudinal studies: A simulation approach in SAS. Computer Methods and Programs in Biomedicine, 2006; 84:27-33.
Delfino RJ, Staimer N, Gillen D, Tjoa T, Sioutas C, Fung K, George S, Kleinman MT. Personal and ambient air pollution is associated with increased exhaled NO in children with asthma. Environ Health Perspect, 2006;114:1736–1743.
Polidori A, Arhami M, Delfino RJ, Allen R, Sioutas C. Indoor-outdoor relationships, trends and carbonaceous content of fine particulate matter in retirement communities of the Los Angeles basin. J Air Waste Manage Assoc, 2007; 57:366-379.
Delfino RJ, Staimer N, Tjoa T, Gillen D, Kleinman MT, Sioutas C, Cooper D. Personal and ambient air pollution exposures and lung function decrements in children with asthma. Environ Health Perspect 2008;116:550-55.
Shinyashiki M, Rodriguez CR, Di Stefano EM, Sioutas C, Delfino RJ, Kumagai Y, Froines JR and Cho AK. On the interaction between glyceraldehyde-3-phosphate dehydrogenase and airborne particles: Evidence for electrophilic species. Atmos Environ, 2008;42:517-529.
Polidori A, Hu S, Biswas S, Delfino RJ, Sioutas C. Real-time characterization of particle-bound polycyclic aromatic hydrocarbons in ambient air and from motor-vehicle exhaust. Atmospheric Chemistry and Physics, 2008 8:1277-91.
Floro JN, Dunton GF, Delfino RD. Assessing physical activity in asthmatic children: accelerometer and electronic diary data. Research Quarterly for Exercise and Sports, 2009;80:153-63.
Delfino RJ, Staimer N, Tjoa T, Polidori A, Arhami M, Gillen D, Kleinman MT, Vaziri N, Zaldivar F, Longhurst J, Sioutas C. Circulating biomarkers of inflammation, antioxidant activity, and platelet activation are associated with urban air pollution in elderly subjects with a history of coronary artery disease. Env Health Perspect, 2008;116:898–906.
Chang J, Delfino RJ, Gillen D, Tjoa T, Nickerson B, Cooper D. Repeated respiratory hospital encounters among children with asthma and residential proximity to traffic. Occup Environ Med, 2009;66;90-98.
Delfino RJ, Brummell S, Wu J, Stern H Ostro B, Lipsett M, Winer A, Street DH, Zhang L, Tjoa T, Gillen D. The relationship of respiratory and cardiovascular hospital admissions to the southern California wildfires of 2003. Occup Environ Med, 2009;66:189-97.
Gorham KA, Sulbaek Andersen MP, Meinardi S, Delfino RJ, Staimer N, Tjoa T, Rowland FS, Blake DR. Ethane and n-pentane in exhaled breath are biomarkers of exposure not effect, Biomarkers 2009;14:17-25.
DiStefano E, Eiguren-Fernandez A, Delfino RJ, Sioutas C, Froines JR, Cho AK. Determination of metal-based hydroxyl radical generating capacity of ambient and diesel exhaust particles. Inhalation Toxicol, 2009;21:731-8.
Delfino RJ, Chang J, Wu J, Ren C, Tjoa T, Nickerson B, Cooper D, Gillen DL. Repeated hospital encounters for asthma in children and exposure to traffic-related air pollution near the home. Ann Allergy Asthma Immunol, 2009;102:138-144.
Arhami M, Polidori A, Delfino RJ, Tjoa T, Sioutas C. Associations between personal, indoor, and residential outdoor pollutant concentrations: Implications for exposure assessment to size fractionated PM. J Air Waste Manage Assoc 2009;59:392–404.
Delfino RJ, Staimer N, Tjoa T, Gillen D, Polidori A, Arhami M, Kleinman MT, Vaziri N, Longhurst J, Sioutas C. Air pollution exposures and circulating biomarkers of effect in a susceptible population: clues to potential causal component mixtures and mechanisms. Environ Health Perspect, 2009;117:1232–1238.
Polidori A, Cheung KL, Arhami M, Delfino RJ, Schauer JJ, Sioutas C. Relationships between size-fractionated indoor and outdoor trace elements at four retirement communities in southern California. Atmospheric Chemistry and Physics, 2009;9:4521-36.
Wu J, Ren C, Delfino RJ, Chung J, Wilhelm M, Ritz B. Association between local traffic-generated air pollution and preterm delivery and preeclampsia in the South Coast Air Basin of California. Environ Health Perspect, 2009;117:1773-1779.
Delfino RJ. Do endotoxin and air pollution have a synergistic relationship to asthma onset or exacerbation? Am Am J Respir Crit Care Med, 2009;180:1037-1038.
Von Behren J, Lipsett M, Horn-Ross PL, Delfino RJ, Gilliland F, McConnell R, Bernstein L, Clarke CA, Reynolds P. Body weight, waist size, and risk of current asthma in the California Teachers Study Cohort. Thorax, 2009;64:889-83.
Arhami M, Minguillón MC, Polidori A, Schauer JJ, Delfino RJ, Sioutas C. Organic compound characterization and source apportionment of indoor and outdoor quasi-ultrafine PM in retirement homes of the Los Angeles basin. Indoor Air, 2010;20:17-30.
Delfino RJ, Tjoa T, Gillen D, Staimer N, Polidori A, Arhami M, Jamner L, Sioutas C, Longhurst J. Traffic-related air pollution and blood pressure in elderly subjects with coronary artery disease. Epidemiology, 2010;21:396-404.
Delfino RJ, Staimer N, Tjoa T, Arhami M, Polidori A, Gillen D, Kleinman MT, Schauer J, Sioutas C. Association of biomarkers of systemic effects with organic components and source tracers in quasi-ultrafine particles. Environ Health Perspect, 2010;118:756-762.
Delfino RJ, Staimer N, Tjoa T, Arhami M, Polidori A, George SC, Shafer MM, Schauer JJ, Sioutas C. Associations of primary and secondary organic aerosols with airway and systemic inflammation in an elderly panel cohort. Epidemiology 2010;21:892-902.
Delfino RJ, Staimer N, Vaziri ND. Air pollution and circulating biomarkers of oxidative stress. Air Qual Atmos Health, 2011;4:37-52.
Delfino RJ, Gillen DL, Tjoa T, Staimer N, Polidori A, Arhami M, Sioutas C, Longhurst J. Electrocardiographic ST segment depression and exposure to traffic-related aerosols in elderly subjects with coronary artery disease. Environ Health Perspect 2011;119:196–202.
Wu J, Jiang C, Houston D, Baker D, Delfino RJ. Automated Time Activity Classification Based on Global Positioning Systems (GPS) Tracking Data. Environ Health 2011;10:101.
Fruin S, Hudda N, Sioutas C, Delfino RJ. Predictive model for vehicle air exchange rates based on a large, representative sample of vehicles in California. Environ Science Technol, Environ Science Technol, 2011;45:3569-3575..
Schwindt CD, Bacchus H, Leu S-Y, Tjoa T, Klebanova Y, Delfino RJ. Characterization of the asthmatic population of St. Vincent and the Grenadines: asthma severity levels and atopic sensitization, J Asthma, 2010;47:871-7.
Delfino RJ, Staimer N, Tjoa T. Personal endotoxin exposure in a panel study of school children with asthma. Environ Health 2011;10:69.
Hudda N, Kostenidou E, Delfino RJ, Fruin SA, Sioutas C. Factors Vehicle and Driving Characteristics That Influence In-Cabin Particle Number Concentrations. Environ Science Technol 2011;45:8691-8697.
Ducret-Stich R, Delfino RJ, Tjoa T, Gemperli A, Wu J, Phuleria HC, Liu L-J S. Examining representativeness of home outdoor models for PM2.5, EC, and OC estimates for daily personal exposures in Southern California. Air Qual Atmos Health 2012;5:335-351.
Staimer N, Cho A, Nizkorodov S, Delfino RJ. Glutathione peroxidase inhibitory assay for electrophilic pollutants in diesel exhaust and tobacco smoke. Anal Bioanal Chem 2012; 403:431-441.
Kam W, Liacos J, Schauer JJ, Delfino RJ, Sioutas C. Size-segregated composition of particulate matter (PM) in major roadways and surface streets. Atmos Environ, 2012;55:90-97.
Largent J, Nickerson B, Cooper D, Delfino RJ. Paediatric asthma hospital utilization varies by demographic factors and area socioeconomic status. Public Health, in press.
Hudda N, Eckel SP, Knibbs LD, Sioutas C, Delfino RJ, Fruin SA. Linking in-vehicle ultrafine particle exposures to on-road concentrations. Atmos Environ, in press 5-2012.
Wu J, Tjoa T, Li L, Jaimes G, Delfino RJ. Modeling Personal Polycyclic Aromatic Hydrocarbon (PAH) Exposure in Human Subjects in Southern California. Environ Health 2012 11:47.
Hudda N, Fruin SA Delfino RJ, Sioutas C. Cost Effective Determination of Vehicle Emission Factors using On-Road Measurements. Atmospheric Chemistry and Physics, in press 7-2012.
Kam W, Liacos JW, Schauer JJ, Delfino RJ, Sioutas C. On-road emission factors of PM pollutants for light-duty vehicles (LDVs) based on urban street driving conditions. Atmospheric Environment 2012;61:378-386.
Liacos J, Kam W, Delfino RJ, Schauer JJ, Sioutas C. Characterization of organic, metal and trace element PM2.5 species and derivation of freeway-based emission rates in Los Angeles, CA. Science of Total Environment, 2012;435-436:159–166.
Wu J, Jiang C, Jaimes G, Bartell S, Dang S, Baker D, Delfino RJ. Travel Patterns During Pregnancy: Comparison Between Global Positioning System (GPS) Tracking and Questionnaire Data, Environ Health, 2012;11:47.
Kam W, Delfino RJ, Schauer JJ, Sioutas C. A comparative assessment of PM2.5 exposures in light-rail, subway, freeway, and surface street environments in Los Angeles and estimated associated lung cancer risk. J Environ Mon, in press 11-2012.
Delfino RJ, Staimer N, Tjoa T, Gillen DL, Schauer JJ, Shafer M. Airway inflammation and oxidative potential of air pollutant particles in a pediatric asthma panel. J Expo Sci Environ Epidemiol, in press, 2/2013.
Bartell S, Tjoa T, Longhurst J, Sioutas C, Delfino RJ. Particulate air pollution, ambulatory heart rate variability and arrhythmia in elderly subjects with coronary artery disease. Submitted to Environ Health Perspect in press 3-2013.
Wittkopp S, Staimer N, Tjoa T, Gillen D, Daher N, Schauer JJ, Sioutas C, Delfino RJ. Mitochondrial genetic background modifies the relationship between traffic-related air pollution exposure and systemic biomarkers of inflammation. PLoS One, in press 4/2012.
NIH/NIEHS, R01 ES11615, recently completed, (RJ Delfino), Pediatric Asthma, Particulate Air Pollution and NO2.
NIH/NIEHS R01 ES012243, recently completed and renewed,(RJ Delfino), Ultrafine Particulate Matter & Cardiorespiratory Health.
Environmental Protection Agency, Southern California Particle Center Award No. UCLA-36488, Prime award No. RD83241301 (Froines; Project 4: Oxidative Stress Responses to PM Exposure in Elderly Individuals with Coronary Heart Disease – Ralph Delfino, Lead Investigator
State of California Air Resources Board, Contract No. 03-329, recently completed, (RJ Delfino), Determination of Reactive Oxygen Species Activity in PM and Enhanced Exposure Assessment for the NIH, NIEHS Study Entitled: Ultrafine Particulate Matter and Cardiorespiratory Health.
NIH, NIEHS, 1 R21 ES-016420 (RJ Delfino), Air Pollution and Peripheral Blood Gene Expression in Subjects with Coronary Artery Disease.
State of California Air Resources Board Contract no 07310 (RJ Delfino), 6/30/2008 – 6/29/2012, In-Vehicle Air Pollution Exposure Measurement and Modeling.
State of California Air Resources Board, Contract No. 07325, recently completed, (RJ Delfino), Personal Endotoxin Exposure in School Children with Asthma.
State of California Air Resources Board, contract no. 08-307 (R.J. Delfino) 12/02/09 – 12/01/12 Personal, indoor and outdoor particulate air pollution and heart rate variability in elderly subjects with coronary artery disease.
South Coast Air Quality Management District / BP Inc. contract no. BPG-46329 (R.J. Delfino) 12/01/09– 11/30/11, Risk of Hospital Encounters for Asthma among Children from Exposure to Traffic-related Air Pollutants near the Home.
NIH, NIEHS, R21 ES016379, recently completed (Jun Wu), 9/1/08-8/30/10, Exposure to mobile source air pollution and adverse birth outcomes in the Los Angeles Air Basin.
PHS-NIH Child Health & Human Services Contract No. HHSN27555200503415C (J. Swanson), 10/01/05 – 03/31/12, Orange County California Vanguard Site for the National Children’s Study.
NIH, NIEHS, R01 ES-012243-06 (R.J. Delfino) 4/15/2011 – 2/01/2016 Transcriptomic, Oxidative Stress, and Inflammatory Responses to Air Pollutants.
NIH, NIEHS, 1 R21 ES-019711 (RJ Delfino), 01/01/2011 – 12/31/2012, Acute Asthma Outcomes, Endotoxin and Oxidative Potential of Pollutant Particles.
NIH, NIEHS, R21 ES-020237 (R.J. Delfino), 7/01/2011 – 06/30/2013, Pediatric asthma, photochemical oxidant air pollutants, and climate change vulnerability
Professional Societies
American Thoracic Society
International Society for Environmental Epidemiology
Other Experience
Air Quality Advisory Committee Member of the
California Air Resources Board (CARB) 2004—2006

Graduate Programs

Research Center
UC Irvine Genetic Epidemiology Research Institute (GERI), Assoc. Director
Last updated