UNLABELLED Student attendance in American public schools is a critical factor in securing limited operational funding. Student and teacher attendance influence academic performance. Limited data exist on indoor air and environmental quality (IEQ) in schools, and how IEQ affects attendance, health, or performance. This study explored the association of student absence with measures of indoor minus outdoor carbon dioxide concentration (dCO(2)). Absence and dCO(2) data were collected from 409 traditional and 25 portable classrooms from 22 schools located in six school districts in the states of Washington and Idaho. Study classrooms had individual heating, ventilation, and air conditioning (HVAC) systems, except two classrooms without mechanical ventilation. Classroom attributes, student attendance and school-level ethnicity, gender, and socioeconomic status (SES) were included in multivariate modeling. Forty-five percent of classrooms studied had short-term indoor CO(2) concentrations above 1000 p.p.m. A 1000 p.p.m. increase in dCO(2) was associated (P < 0.05) with a 0.5-0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10-20% increase in student absence. Annual ADA was 2% higher (P < 0.0001) in traditional than in portable classrooms. PRACTICAL IMPLICATIONS This study provides motivation for larger school studies to investigate associations of student attendance, and occupant health and student performance, with longer term indoor minus outdoor CO(2) concentrations and more accurately measured ventilation rates. If our findings are confirmed, improving classroom ventilation should be considered a practical means of reducing student absence. Adequate or enhanced ventilation may be achieved, for example, with educational training programs for teachers and facilities staff on ventilation system operation and maintenance. Also, technological interventions such as improved automated control systems could provide continuous ventilation during occupied times, regardless of occupant thermal comfort demands.

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Associations between classroom CO2 concentrations and student attendance in Washington and Idaho

Student attendance in American public schools is a critical factor in securing limited operational funding. Student and teacher attendance influence academic performance. Limited data exist on indoor air and environmental quality (IEQ) in schools, and how IEQ affects attendance, health, or performance. This study explored the association of student absence with measures of indoor minus outdoor carbon dioxide concentration (dCO{sub 2}). Absence and dCO{sub 2} data were collected from 409 traditional and 25 portable classrooms from 14 schools located in six school districts in the states of Washington and Idaho. Study classrooms had individual heating, ventilation, and air conditioning (HVAC) systems, except two classrooms without mechanical ventilation. Classroom attributes, student attendance and school-level ethnicity, gender, and socioeconomic status (SES) were included in multivariate modeling. Forty-five percent of classrooms studied had short-term indoor CO{sub 2} concentrations above 1000 parts-per-million (ppm). A 1000 ppm increase in dCO{sub 2} was associated (p < 0.05) with a 0.5% to 0.9% decrease in annual average daily attendance (ADA), corresponding to a relative 10% to 20% increase in student absence. Outside air (ventilation) rates estimated from dCO{sub 2} and other collected data were not associated with absence. Annual ADA was 2% higher (p < 0.0001) in traditional than in portable classrooms.

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Indoor air quality (IAQ) parameters in 64 elementary and middle school classrooms in Michigan were examined for the purposes of assessing ventilation rates, levels of volatile organic compounds (VOCs) and bioaerosols, air quality differences within and between schools, and emission sources. In each classroom, bioaerosols, VOCs, CO2, relative humidity, and temperature were monitored over one workweek, and a comprehensive walkthough survey was completed. Ventilation rates were derived from CO2 and occupancy data. Ven- tilation was poor in many of the tested classrooms, e.g., CO2 concentrations often exceeded 1000 ppm and sometimes 3000 ppm. Most VOCs had low con- centrations (mean of individual species <4.5 lg/m 3 ); bioaerosol concentrations were moderate (<6500 count per m 3 indoors, <41,000 count per m 3 outdoors). The variability of CO2, VOC, and bioaerosol concentrations within schools exceeded the variability between schools. These findings suggest that none of the sampled rooms were contaminated and that no building-wide contamination sources were present. However, localized IAQ problems might remain in spaces where contaminant sources are concentrated and that are poorly ventilated.

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Indoor air quality in Michigan schools.

Ozone consumption and volatile byproduct formation from surface reactions with aircraft cabin materials and clothing fabrics

We have used multiple analytical methods to characterize the gas-phase products formed when ozone was added to cabin air during simulated 4-hour flights that were conducted in a reconstructed secti...

Ozone-initiated chemistry in an occupied simulated aircraft cabin.

UNLABELLED: Ozone concentrations were passively monitored in passenger cabins of commercial airliners flying domestic, Pacific, and south-east Asian routes. One-hundred and six flight segments were monitored for either the full duration and/or approximately 3 h during the middle portion of the flight for a total of 145 time-integrated measurements. Over all samples the mean (+/-SD) concentration was 80 p.p.b. (30.1). Twenty percent of the measurements exceeded 100 p.p.b., the FAA-recommended level. Eleven percent of the measurements exceeded 120 p.p.b., the US EPA's short-term National Ambient Air Quality Standard for ozone. Ozone concentrations measured on Pacific flights were substantially higher during mid-flight than over the full flight (95 p.p.b. vs. 56 p.p.b). Ozone concentrations on the northern Pacific routes were higher than concentrations for other Pacific flights. Season comparison showed that ozone levels were higher during the winter and spring than for the summer and fall. Our study shows that even in aircraft with catalytic ozone converters, passengers and flight crew may be exposed to elevated ozone levels on domestic and international flights. Given the frequency of ozone excess, it is recommended that (1) ozone converters should be required equipment on all commercial passenger aircraft for mid and high latitude routes (2) improved maintenance procedures should be required for catalytic converters (e.g., more frequent servicing/replacement), and (3) ozone should be routinely monitored on all mid and high latitude flights. PRACTICAL IMPLICATIONS: The authors have demonstrated elevated ozone concentrations in passenger cabins. They give several practical recommendations to help solve the problem.

Ozone exposures during trans-continental and trans-pacific flights

UNLABELLED The prevalence of prefabricated, portable classrooms (portables) for United States public schools has increased; in California, approximately one of three students learn inside portables. Limited research has been conducted on indoor air and environmental quality in American schools, and almost none in portables. Available reports and conference proceedings suggest problems from insufficient ventilation due to poor design, operation, and/or maintenance of heating, ventilation and air conditioning (HVAC) systems; most portables have one mechanical, wall-mounted HVAC system. A pilot assessment was conducted in Los Angeles County, including measurements of integrated ventilation rates based on a perfluorocarbon tracer gas technique and continuous monitoring of temperature (T) and relative humidity (RH). Measured ventilation rates were low [mean school day integrated average 0.8 per hour (range: 0.1-2.9 per hour)]. Compared with relevant standards, results suggested adequate ventilation and associated conditioning of indoor air for occupant comfort were not always provided to these classrooms. Future school studies should include integrated and continuous measurements of T, RH, and ventilation with appropriate tracer gas methods, and other airflow measures. PRACTICAL IMPLICATIONS Adequate ventilation has the potential to mitigate concentrations of chemical pollutants, particles, carbon dioxide, and odors in portable and traditional classrooms, which should lead to a reduction in reported health outcomes, e.g., symptoms of 'sick building syndrome', allergies, asthma. Investigations of school indoor air and environmental quality should include continuous temperature and relative humidity data with inexpensive instrumentation as indicators of thermal comfort, and techniques to measure ventilation rates.

R. A. Weker

Papers

Ozone exposures during trans-continental and trans-pacific flights

Evidence of inadequate ventilation in portable classrooms: results of a pilot study in Los Angeles County.