Asthma & Exposure to Peaks in Particulate Air Pollution

This study has been completed.
Sponsor:
Information provided by:
National Institute of Environmental Health Sciences (NIEHS)
ClinicalTrials.gov Identifier:
NCT00013728
First received: March 28, 2001
Last updated: March 22, 2006
Last verified: March 2006
  Purpose

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.


Condition
Asthma

Study Type: Observational
Study Design: Observational Model: Defined Population
Time Perspective: Longitudinal

Resource links provided by NLM:


Further study details as provided by National Institute of Environmental Health Sciences (NIEHS):

Estimated Enrollment: 24
Study Start Date: September 2000
Estimated Study Completion Date: October 2003
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.

  Eligibility

Ages Eligible for Study:   9 Years to 18 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

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.

  Contacts and Locations
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  More Information

No publications provided

ClinicalTrials.gov Identifier: NCT00013728     History of Changes
Other Study ID Numbers: 6214-CP-001
Study First Received: March 28, 2001
Last Updated: March 22, 2006
Health Authority: United States: Federal Government

Keywords provided by National Institute of Environmental Health Sciences (NIEHS):
asthma
particulate matter

Additional relevant MeSH terms:
Asthma
Bronchial Diseases
Respiratory Tract Diseases
Lung Diseases, Obstructive
Lung Diseases
Respiratory Hypersensitivity
Hypersensitivity, Immediate
Hypersensitivity
Immune System Diseases

ClinicalTrials.gov processed this record on September 14, 2014