Purpose: The primary purpose of this study is to measure pulmonary function, symptoms, and pulmonary inflammatory responses in healthy young adults during and immediately after exposure to a low concentration of ozone (0.070 ppm) or clean air for 6.6 hours while undergoing moderate intermittent exercise. This concentration is the current EPA NAAQS standard for ozone.
Potential health effects of ozone have been extensively studied over decades at various levels of exposure concentration and for varying time periods in young healthy adult subjects. Effects of ozone have been well documented particularly for decrements of lung function and an influx of neutrophils and other markers of pulmonary inflammation. The majority of those studies were done at ozone concentrations between 0.12 and 0.40 ppm, considerably higher than the current EPA NAAQS ozone standard of 0.070 ppm, and at exposure durations of two hours, even though the current standard is an 8-hour standard. However, a small number of studies have assessed changes in lung function following exposure to low levels of ozone for several hours. These latter studies have shown that exposure to ozone for 6.6 hours at concentrations between 0.06 and 0.08 ppm causes mild reversible decrements in lung function (1.7-10%) as measured by forced vital capacity (FVC) and forced expired volume at 1 s (FEV1) immediately after exposure in healthy young adults. In addition, in one study an increase in ozone-induced neutrophils was seen in induced sputum following exposure to 0.06 ppm ozone (8) and in bronchoalveolar lavage fluid) following exposure to 0.08 ppm ozone (9). The EPA is considering whether the current ozone NAAQS standard at 0.070 is protective and has asked EPA researchers to conduct a study similar to those done at 0.06 and 0.08 ppm.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
60
The concentration of ozone a subject will randomly receive on a visit for 6.6 hours in a controlled atmospheric chamber while performing moderate intermittent exercise.
Same subject will randomly receive clean air on another visit separated by at least one week for 6.6 hours in the same controlled atmospheric chamber while performing moderate intermittent exercise.
EPA Human Studies Facility
Chapel Hill, North Carolina, United States
RECRUITINGFVC
forced vital capacity
Time frame: measured (pre) before starting 6.6 hours of exercise
Change in FVC
change in forced vital capacity
Time frame: change measured (post) immediately after 6.6 hours of exercise
FEV1
forced expiratory volume in 1 second
Time frame: measured (pre) before starting 6.6 hours of exercise
Change in FEV1
change in forced expiratory volume in 1 second
Time frame: change measured (post) immediately after 6.6 hours of exercise
% neutrophils collected by induced sputum
Subjects will breathe a hypertonic saline solution from an ultrasonic nebulizer through a mouthpiece at saline concentrations of 3%, 4%, and 5%. After each inhalation period subjects be asked to cough up the expectorate in a sterile cup for analysis of neutrophil cells influx
Time frame: baseline: training/qualification day
change in % neutrophils collected by induced sputum
Subjects will breathe a hypertonic saline solution from an ultrasonic nebulizer through a mouthpiece at saline concentrations of 3%, 4%, and 5%. After each inhalation period subjects be asked to cough up the expectorate in a sterile cup for analysis/quantitation of neutrophil cells influx
Time frame: 18 hours post exposure
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