Children's Exposures/Health Effects/Diesel Exhaust

We will recruit 450 subjects ranging from 9 to 11 years old (or 3rd to 5th graders). These children who commute to school will perform repeated monthly measures of pulmonary function tests using spirometry, pulmonary inflammation via exhaled breath, and asthma symptoms and clinical encounters, up to 3 school years. These 500 children will represent 3 exposure scenarios: 1) one group of 125 children riding retrofitted school buses or private cars; 2) 250 children riding old buses who will change to retrofitted buses during the first or second year of the study; and 3) 125 children who ride old diesel buses through the study. All subjects will be either healthy or having physician-diagnosed asthma with severity ranging from mild intermittent to moderate persistent. Personal exposure monitoring of particulate matter, CO, NO2, and SO2 will be performed on a subset of 144 asthmatic subjects, with each subject being monitored for up to 2 days, in each monitoring year.

Subjects participating in the study will wear a small backpack containing several personal air monitors measuring real-time particulate matter concentrations and carbon monoxide concentrations as well as integrated (24 hour averaged) measurements of SO2 and NO2. The children's personal monitoring will begin when they wake up in the morning and continue for 24-hours. When wearing the backpack is inconvenient, such as when sleeping, the monitoring equipment should be placed in close proximity to the subject. Once the subject arrives at school, s/he will be asked to perform three respiratory tests: exhaled nitric oxide, exhaled breath condensate, and spirometry. At the end of the school day, the subject will be asked to perform the same two tests of lung function as earlier, plus an additional test of exhaled breath condensate. The subject will then continue his/her day as normal. A technician will replace the filter in the particulate matter monitor between 6 and 7 PM. We will repeat the same monitoring procedure the following morning when the subject wakes up for another 24-h. Monitoring will stop on the third morning when the subjects wake up. In addition to the personal monitoring, a monitoring kit will be installed in the subject's school bus and will be operated by a technician. This in-vehicle monitoring kit includes everything contained in the personal monitoring kit, plus a P-TRAK (TSI, model 8525) for real-time ultra-fine particle counts, two Harvard Personal Environmental Monitors (HPEM) with Teflon and quartz filters respectively for determining elemental carbon fractions, an EcoChem PAS2000CE monitor for polycyclic aromatic hydrocarbons (PAHs), and a global positioning system personal acquisition logger (GPS-PAL). The following timeline shows the typical daily schedule for a subject participating in the study.