Proposal:
Execute a Contract to Evaluate Allergens in Paved Road Dust and Airborne Particles
Synopsis:
The objective of this proposed study is to determine the contribution of road dust to the toxicity of ambient particles (PM10). The information can subsequently be used to determine the extent of health benefits likely to be derived from road dust control measures to achieve ambient PM10 target levels in different areas of the Basin. Staff recommends cosponsoring this study by the California Institute of Technology in an amount not to exceed $50,000. The California Air Resources Board will provide $104,000 to cost-share this study.
Committee:
Technology, February 13, 1996, Recommended for Approval
Recommended Action:
Authorize the Executive Officer to execute a contract with the California Institute of Technology, in an amount not to exceed $50,000.
James M. Lents, Ph.D.
Executive Officer
MN:SP:dv
Background
The South Coast Air Basin is required to attain the National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM10) by the year 2006. In urban areas, road dust accounts for 30-50% of ambient PM10 levels. A recent study suggests that the latex (derived from wear and tear of tires) portion in road dust is probably responsible for the observed increase of asthma incidence in the general population. However, neither the toxic effects of road dust, nor the allergenic potential of the latex portion (likely to cause or exacerbate asthma) have been established. Hence, the extent of public health benefits likely to be derived from controlling road dust cannot be estimated.
Proposal
The proposed study will characterize the major allergens found in both road dust and ambient air samples of PM10, and will estimate the road dust contributions to ambient PM10 levels. Ambient air samples will be collected over a period of six months at three monitoring sites (Long Beach, Los Angeles and Rubidoux). Paved road dust samples will also be collected from areas adjacent to these monitoring sites. Both will be analyzed for their chemical composition and for allergenic potential in humans.
Organic and elemental carbon content will be determined by thermal evolution and combustion analysis; sulfates, nitrates and chloride by ion chromatography; sodium, calcium and magnesium levels by atomic adsorption spectrophotometry; and trace elements by X-ray fluorescence. These chemical composition results will be used to estimate the contribution of road dust to ambient PM10 levels by using a chemical mass balance (CMB) model.
State-of-the-science immunological techniques will be used to quantify allergens in the samples collected. The technique is based on a competitive reaction where an unknown amount of allergens (antigens in the samples collected) compete with a known amount of known labeled allergens to bind with a fixed amount of antibodies. The more the environmental allergen, the less labeled allergen can bind to the antibody. Following binding, the quantity of labeled allergen-antibody combinations is measured and the amount of unknown is calculated by the difference. Western blot techniques will be used to screen and identify the types of allergens found in the collected samples.
The expected benefit of the proposed is an improved understanding of the potential health effects of PM10. The results of these assays, coupled with the source contribution information gained by the CMB analysis, will provide considerable insight to determine the relative toxicity of road dust. This information will also be critical to decide whether significant health benefit is likely to be derived from targeting this fraction for future control measures in efforts to attain the PM10 NAAQS.
Sole-Source Justification
Section II, Step C(3) of the Consultant Selection Policy identifies four provisions under which a sole-source award may be justified; (1) cost to prepare documents exceeds the cost for consultants,(2) delay would result in the endangerment of public health or property, (3) services are only available from the sole-source, (4) other circumstances exist identifying the sole-source as in the best interests of the AQMD. This request for a sole-source award is being made under provision #4. The contractor was selected by the California Air Resources Board (ARB), which is providing over two thirds ($104,256) of the funds to conduct the study. The costs associated with daily monitoring at multiple sites are prohibitive to consider a similar study at a later time. However, ambient samples are being collected at no additional costs by the ongoing enhanced PM10 monitoring program at the AQMD. Hence, joining the ARB to cosponsor this study by providing $50,000 from the AQMD will result in considerable cost savings in an effort to obtain critical information for designing future control strategies.
Thus, it is in the AQMD's best interest to fund this study for evaluating allergens in paved road dust and air borne particles in an effort to design future control strategies which will provide maximum health benefits to the Basin's residents.
Resource Impacts
The total cost of the proposed project is $154,256. The ARB will contribute $104,256 and has requested a $50,000 cost share from the AQMD to fund this project. Sufficient funds are available in the Advanced Technology Fund to support this project.
BD13:3-96G