Environmental studies headed by Dr. Ralph J. Delfino in the Department of Epidemiology have been conducted in San Diego and Los Angeles Counties. They have focused on the relationship of daily asthma severity to air pollutants and to aeroallergens using repeated measurements. This has involved following panels of around 20-30 asthmatics intensively for 2-3 months using peak flow meters or spirometers, and daily diaries for reporting asthma symptoms, medication use, spatial location and physical activity. The research also involves exposure assessments involving air-monitoring systems inside and outside of subject homes, and personal air samplers that subjects carry with them during their daily activities (1-4). Our first panel study showed personal ozone exposure but not outdoor stationary site ozone (O₃) was positively associated with daily asthma severity in children (1). Several of our panel studies have shown positive associations of asthma symptom severity in schoolchildren with outdoor fungal spores (1, 5-7) and pollen (7). These aeroallergens did not confound significant air pollutant effects. We also showed adverse effects on asthma symptoms from increases in daily 1-hr and 8-hr maximum PM₁₀ (particulate matter, aerodynamic diameter < 10µm) in addition to 24-hr average PM₁₀ (7, 8). The current averaging time for federal regulation of PM₁₀ and PM_2.5 is 24 hours. In addition, air pollutant and aeroallergen effects were notably greater among asthmatics not taking anti-inflammatory medications (7, 8).

Our initial research results on effects of peak 1-hr and 8-hr particle exposures prompted our current work funded by NIH, NIEHS. Ongoing analysis is being conducted for a study that involves intensive personal particle exposure assessments and dosimetric work in a panel of schoolchildren with asthma. Participants use electronic diaries and wear light scattering devices to provide continuous monitoring of particle exposure. We are testing the hypotheses that: 1) peak hourly exposures to particulate matter of outdoor origin will be more closely associated with acute asthmatic responses to particles than 24-hour average exposures; and 2) estimates of personal hourly particle exposures from microenvironmental models, and estimated particle dose to target zones in the respiratory tract will be more closely associated with daily asthma severity than unadjusted outdoor particle concentrations. Findings may partly explain epidemiological findings for adverse effects of regulated 24-hour average PM₁₀ at levels below 150 mg/m³ (the U.S. National Ambient Air Quality Standard).

Another panel study was conducted involving Hispanic schoolchildren with asthma living in a region of Los Angeles County with high traffic density and high ambient air concentrations of toxic air pollutants, including volatile organic compounds (VOCs) such as benzene. We found ambient petroleum-related VOCs measured on the same person-days as exhaled breath concentrations of VOCs showed notably stronger positive associations with asthma symptoms than the breath measurements (8). VOCs included toluene, m,p-xylene, o-xylene, and benzene. Additional analyses over the 3-month daily component of this panel showed positive associations of asthma symptoms with several VOCs, US EPA principal criteria air pollutants [O₃, nitrogen dioxide (NO₂) sulfur dioxide (SO₂) and PM₁₀], and organic carbon and elemental carbon fractions of PM₁₀ (EC-OC) (9). For an increase to mean concentrations, bothersome or more severe asthma symptoms were 3.0 times more likely for EC, 3.6 times more likely for OC and 1.8 times more likely for PM₁₀. Two-pollutant regression models of EC or OC with PM₁₀ showed little change in adjusted odds ratios from single pollutant models for EC or OC, but PM₁₀ decreased 1.0. Organic compounds such as polycyclic aromatic hydrocarbons or other combustion products in diesel or automobile exhaust may have driven these particle associations. Taken together, these findings support the view that toxic air pollutants in the pollutant mix from traffic and industrial sources may have adverse effects on asthma.

Upcoming research funded by NIH, NIEHS involves intensive personal exposure assessments for NO₂, PM₁₀ and EC-OC. This is part of an overall interest in the Department of Epidemiology to assess the importance of air pollutants to acute asthma exacerbations in children, and to assess the relative role of toxic air pollutants to effects of regulated principal criteria air pollutants such as particle mass or NO₂ (10).

Dr. Delfino and colleagues have also performed analyses on the relationship between emergency room visits to 25 hospitals for respiratory illnesses and air pollution in Montreal, Canada (11, 12). We found adverse effects on emergency room visits for respiratory illnesses among the elderly by summertime levels of ozone and particulate air pollutants well below US EPA air quality standards. Hospital admissions for asthma and other respiratory illnesses were also positively associated with ambient air pollutants (13). The overall burden of respiratory illnesses from air pollution could be much larger than that suggested by this and similar time series studies of hospital data when considering less severe clinical expressions of respiratory morbidity (symptom exacerbations, increased medication use and lung function decrements). We continue to contribute to this area of research by conducting panel studies in potentially susceptible populations.

Recent work of the Department of Epidemiology with Dr. Dan Cooper in the Department of Pediatrics, UCI and Dr. Bruce Nickerson of the Children’s Hospital of Orange County (CHOC) includes the development of research designs for the new Asthma and Chronic Lung Disease (CLD) Institute. This is a collaborative effort between CHOC and UCI Medical Center to work with the appropriate Orange County community-based resources to create comprehensive and integrated approaches to assuring access to quality care for the children of Orange County with asthma and CLD. Drs. Delfino and Carpenter in the UCI Department of Epidemiology will assist the Institute in creating an innovative, state-of-the-art database and outcome-focused tracking system to monitor care provided and health outcomes in these children. This will be accomplished through the development and implementation of a surveillance system to capture data on children ages 0-8 living in Orange County with health outcome characteristics that are associated with the development and persistent severity of asthma and CLD. This system will identify and track these children by age, race/ethnicity, geographic location, illness severity, medical home, asthma risk factors and relevant exposures, including traffic-related air pollutant exposures. This data will be used to develop prevention programs that more accurately target populations at risk. The system will conduct on-going evaluation and measurement to assess the impact of key exposures or risk factors, health promotion programs, and medical interventions.

1. 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.
2. Liu L-J S, Delfino RJ, Koutrakis P. Ozone exposure assessment in a southern California community. Environ Health Perspect, 1997; 105:58-65.
3. Quintana PJE, Samimi BS, Kleinman MT, Liu S, Soto K, Buffalino C, Warner G, Valencia J, Francis D, Hovell MH, Delfino, RJ. Assessment of personal exposure to fine particulate matter in asthmatic children using a real-time sampler: sampler performance. J Expo Analysis Environ Epidemiol, 2000; 10:437-45.
4. 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.
5. 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.
6. 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.
7. 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.
8. Delfino RJ, Gong H Jr, Linn WS, Hu Y, Pellizzari ED. Respiratory symptoms and peak expiratory flow in children with asthma in relation to volatile organic compounds in exhaled breath and ambient air. J Expo Analysis Environ Epidemiol 2003; 13:348-63.
9. Delfino RJ, Gong H Jr, Linn WS, Hu Y, Pellizzari ED. Asthma symptoms in Hispanic children and daily ambient exposures to toxic and criteria air pollutants. Environ Health Perspect 2003; 111:647-656.
10. 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.
11. 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.
12. 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.
13. 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.