The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts


Kitty Hernlen, Susan Johnson, Randall Baker; georgia health sciences university, Augusta, GA

Background: Increased indoor carbon dioxide (CO2) levels can impact the central nervous system leading to daytime sleepiness and decreased concentration. According to the American Association of Heating Refrigerating and Air-conditioning Engineers (ASHRAE), the upper level of indoor carbon dioxide levels is 1500 ppm. A previous study found higher than normal CO2 levels in classrooms at a middle school in rural Georgia. This study was designed to determine if the implementation of IAQ measures would reduce these CO2 levels. Methods: The ASHRAE standard 62-2001 recommends 700 ppm above the outdoor concentration as the upper limit for occupied classrooms. CO2 measurements were obtained using a pSense AZ 77535A portable CO2 monitor which also recorded relative humidity and temperature. On April 19, 2011, measurements were obtained outside the school as well as in 32 classrooms. Outside CO2 measure was 780 ppm, RH 71% and temperature 20.2 C. An IAQ policy change that prohibited air vents from being blocked or turned off was implemented in August 2011. A follow-up walk thru following the same procedure was conducted on November 17, 2011 to assess the results of the IAQ changes. Outside CO2 levels at that time was 775 ppm, RH 79% and temperature 17.8 C. Results: Paired t-tests were used to examine whether temperature, relative humidity and CO2 changed from pre-test to post-test,. To examine whether blocking of the vents or closing of at least one vent in the room changed from pre- to post-test, the McNemarÂ’s test was used. An improvement in the CO2 levels was seen with the CO2 levels dropping significantly from pre- to post-test (p < 0.0001). A rise in relative humidity in the rooms was seen from pre- to post-test (p=0.0010) with no different in temperature seen in the rooms from pre- to post test. A significant change in the blocked vents from pre- to post-test was seen with more vents that were blocked at pre-test being un-blocked at post-test than the reverse. However, a greater proportion of vents that were open at pre-test were closed at post-test rather, which is concerning. Conclusion: CO2 levels did drop as a result of the policy change to not block vents but the mean post-test CO2 levels remained above the recommended levels. A significant number of vents were turned off reflecting a disregard for the policy change. Reinforcement of the policy needs to be performed by the school. Sponsored Research - W.G. Raoul Foundation Table 1: Paired t-test differences in room data.