Asthma & Exposure to Peaks in Particulate Air Pollution

March 22, 2006 updated by: National Institute of Environmental Health Sciences (NIEHS)
We are testing the following two hypotheses: 1) Peaks in hourly exposures to airborne particulate matter (PM) of outdoor origin will be more closely associated with acute asthmatic responses to particles than 24-hour average exposures in susceptible individuals; 2) Personal exposure to PM, and estimated particle dose to the lungs, will be more closely associated with daily asthma severity than standard outdoor particle concentrations measured as 24-hour averages at governmental monitoring sites.

Study Overview

Status

Completed

Conditions

Detailed Description

We are testing the following two hypotheses: 1) Peaks in hourly exposures to airborne particulate matter (PM) of outdoor origin will be more closely associated with acute asthmatic responses to particles than 24-hour average exposures in susceptible individuals; 2) Personal exposure to PM, and estimated particle dose to the lungs, will be more closely associated with daily asthma severity than standard outdoor particle concentrations measured as 24-hour averages at governmental monitoring sites. Toxicological data for asthma exacerbations from particulate matter (PM) suggests that particle deposition in the lower respiratory tract can cause inflammatory and lung function changes suggestive of asthma pathology. There is now a scientific need to explain epidemiological findings of ambient PM effects on asthmatics at mass concentrations below what is expected (from toxicological data) to be harmful. One possibility is that study participants are encountering unmeasured short-term excursions of particle mass levels capable of inducing adverse reactions in the lung, but this effect is only captured somewhat by the regulatory standard of 24-hour averages. Our research in southern California is vital to the current controversy regarding regulatory standards given that a health-based scientific rationale for any specific PM averaging time is not established.

Study Type

Observational

Enrollment

24

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

9 years to 18 years (Child, Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

1) physician-diagnosed asthma, at least a 1 yr. history, including episodic symptoms of wheezing, cough and dyspnea; 2) mild to moderate severity of asthma: i) a history of at least several weeks during the warm seasons (Mar-Oct) during which the subject required regular daily use of prescribed prophylactic asthma medications; & ii) asthma exacerbations at least 2 days/week requiring as-needed bronchodilators during an extended period of 1-2 warm season months; 3) age from 9-18; 4) home, school or work addresses in Alpine, CA area; 5) no history of smoking by the subjects and no person smoking in the subject?s home.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Defined Population
  • Time Perspectives: Prospective

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Institute of Environmental Health Sciences (NIEHS)

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 1, 2000

Study Completion

October 1, 2003

Study Registration Dates

First Submitted

March 28, 2001

First Submitted That Met QC Criteria

March 29, 2001

First Posted (Estimate)

March 30, 2001

Study Record Updates

Last Update Posted (Estimate)

March 23, 2006

Last Update Submitted That Met QC Criteria

March 22, 2006

Last Verified

March 1, 2006

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 6214-CP-001

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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