1999 Progress Report: Testing of a Model to Predict Human Exposures to Aldehydes Arising from Mobile and Point SourcesEPA Grant Number: R826787
Title: Testing of a Model to Predict Human Exposures to Aldehydes Arising from Mobile and Point Sources
Investigators: Raymer, James H. , Akland, Gerald G. , Clayton, C. Andrew , Johnson, Ted , Pellizzari, Edo D.
Current Investigators: Raymer, James H. , Akland, Gerald G. , Clayton, C. Andrew , Johnson, Ted , Michael, L. C. , Pellizzari, Edo D.
Institution: Desert Research Institute , TRJ Environmental Inc.
EPA Project Officer: Chung, Serena
Project Period: October 1, 1998 through September 30, 2002 (Extended to September 30, 2003)
Project Period Covered by this Report: October 1, 1998 through September 30, 1999
Project Amount: $629,841
RFA: Urban Air Toxics (1998) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
Objective:The main objective of the proposed program is to estimate human exposure to target aldehydes (formaldehyde, acetaldehyde, acrolein, propionaldehyde, butyraldehyde, crotonaldehyde, glyoxal, methylglyoxal) by means of microenvironmental and personal exposure monitoring for two urban areas. The main hypothesis to be tested is that a mathematical model (pHAP) can be used to predict personal exposure distribution to aldehydes. Additional hypotheses to be tested are that: (1) personal exposure levels of aldehydes exceed outdoor concentrations; (2) indoor aldehyde concentrations exceed outdoor concentrations; and (3) the composition of oxygenated fuel results in significant differences in population exposures to aldehydes.
Data to be used in characterizing the Sacramento study area with respect to historical aldehyde levels, historical meteorological conditions, background CO concentrations, CO emissions, housing patterns, and traffic patterns were acquired, reviewed, and summarized. This information assisted the research team in the selection of subjects for the personal exposure portion of the study (Phase A) and monitoring locations for the scripted study (Phase B). Documents to be used to collect data during Phases A and B, including the background questionnaire, the monitoring period questionnaire, the scripted activity diary, and the 24-hour monitoring period diary were prepared and revised. IRB approval was obtained. Data collection protocols for field activities, including a list of planned field measurements and a proposed sequence for interviewing subjects, was prepared.
Participants were selected to represent seven sectors of the Sacramento Metropolitan area, including upwind (Elk Grove), downtown, and downwind locations. In most cases, these areas also are represented by an existing fixed site monitor, operated by the local Sacramento Air Quality Control District. Residents living within the sectors were selected at random from a list of those homes with telephones. The list of approximately 8000 names was provided by zip code, within location (e.g., zip codes that made up the residential area, such as Carmichael, Roseville, etc.). RTI randomly selected names from this list (414 names). Each of these residents received a lead letter that explained the study and how they could either volunteer to participate by calling RTI directly, or if called by a telephone interviewer, they would then be given an opportunity to volunteer. Those determined to be ineligible (17.4 percent) were ineligible because there was a smoking member in the household. Reasons for refusal (34.3 percent) were primarily because most respondents terminated the connection without further discussion. The refusal rate varied by location within the city, from a low of 24.2 percent in Carmichael, to a high of 68.8 percent in North Highlands. Four participants volunteered based on a referral from a participant; two participants lived in Roseville, one lived in Elk Grove, and one lived in the downtown area of Sacramento. In the end, sampling was completed for 38 participants.
The field study was conducted in Sacramento during August and early September 1999. Fifteen scripted sampling periods were completed and two of these were those scripts defined as conditional (downwind of downtown), and they were sampled on days with high ozone levels to see if there was any measurable increase in aldehydes that could be related to photochemical conversion proceses. A total of 38 participants were sampled in the personal exposure portion of the study. A total of 348 aldehyde samples (including duplicates and blanks) and 20 aldehyde field controls were colleted. A total of 210 VOC samples (including duplicates) were collected. Additional samples were designated as field controls and field blanks. Sample analysis was begun. The VOC data and CO data for the scripted portion of the study will permit the identification of combustion sources that could contribute to the aldehyde concentrations in particular microenvironments. It should be noted that forest fires were ongoing nearby for a large portion of the study. On many days, smoke could be smelled and often seen. The extent to which this will interfere with the objectives of the study is not clear at this time.
The following activities are planned for the second year of the project:
- Complete sample analysis, QA data and create a database of results.
- Receive data on air exchange and aldehyde QA.
- Transfer questionnaire data to a database.
- QA field data.
- Create scripts for the study in Milwaukee planned for the summer of 2000.
- Conduct field study in Milwaukee.
- Begin analysis of field samples from Milwaukee.
- Begin data analysis.
In addition, the analysis of aldehyde QA samples will be done using LC/MS in order to obtain both qualitative and quantitative data on aldehydes in different microenvironments.