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Respiratory Deposition of Fine and Coarse Particles during Moderate Exercise
Citation:
Kim, C. AND S. Hu. Respiratory Deposition of Fine and Coarse Particles during Moderate Exercise. Presented at American Association for Aerosol Research, October 08 - 12, 2012.
Impact/Purpose:
Breathing patterns change during exercise and this has a direct impact on risk to exposure to ambient pollutants. Hopwever, specific data for lung deposition and dose of particulate matter are lacking for exercise conditions.
Description:
During exercise breathing patterns change by increasing ventilation rate and this has a direct impact on risk to exposure to ambient pollutants. Although the number of people increases participating in more active life styles, specific data for lung deposition of particulate matter are lacking for exercise conditions. We measured total lung deposition (TDF) of micron-sized aerosols (Dp=1, 3 and 5 um diameter) in 15 healthy individuals (8M/7F) with breathing patterns of both resting (Vt =500-750 ml and f = 12-15 min-1) and moderate exercise (Vt =1000-1500 ml and f = 20-30 min-1) conditions. The minute ventilation (Vmin) was 7.5 and 30 l/min, respectively. Subjects inhaled the test aerosols via the mouth while both aerosol concentration and breathing pattern were being continuously monitored. TDF for each breath was determined and deposition rate (Drate) was calculated by TDF x Vmin, an indicative of lung deposition per minute. TDF was 0.18, 0.48 and 0.64 at rest and 0.15, 0.53 and 0.80 during exercise for Dp = 1, 3 and 5 um, respectively. TDF decreased for Dp=1 um (-20%) but increased for Dp = 3 um (+12%) and 5 um (+25%) during exercise. Drate was 1.38, 3.56 and 4.79 at rest and 4.44, 16.0 and 23.9 during exercise for Dp = 1, 3 and 5 um, respectively. Compared to resting, Drate increased by 3.2, 4.5 and 5.0 times during exercise for Dp = 1, 3 and 5 um, respectively and the increase was smaller by 20% for Dp = 1 um, comparable for Dp = 3 um and greater by 25% for Dp = 5 um than Vmin ratio of 4 (exercise vs. resting). In conclusion, during exercise lung deposition rate increases more rapidly for larger size particles and this may result in a greater risk to exposure to coarse than fine particles. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.