Study: Improved classroom ventilation could reduce student absences

June 7, 2013

California could significantly improve elementary school student attendance and health by increasing the amount of fresh air coming into classrooms, according to the largest U.S. study to date of ventilation rates in classrooms.

Poor ventilation in classrooms is correlated with student absences due to illness, researchers at the Lawrence Berkeley National Laboratory found, and they calculated that increasing air flow in all California classrooms to state-mandated ventilation rates may have potentially significant effects: reducing student absences caused by illness by 3.4 percent and, because schools are funded based on average daily attendance, increasing overall state funding to schools by $33 million.

“Our overall findings suggest that, if you increased ventilation rates of classrooms up to the state standard, or even above it, you would get net benefits to schools, to families, to everybody, at very low cost,” Berkeley lab scientist Mark Mendell, lead author of the study, published in the journal Indoor Air, said in a news release. “It’s really a win-win situation.”

The Berkeley Lab scientists collected data from 28 schools in three California school districts in the Central Valley, the Bay Area and the south coast, but the study did not identify the districts. Instrumental to the study were small environmental sensors placed in 162 3rd, 4th and 5th grade classrooms, which allowed researchers to measure carbon dioxide levels as 5-minute averages. The data were transmitted online to the researchers, who compared indoor carbon dioxide levels to estimates of outdoor carbon dioxide levels to calculate ventilation rates.

“Over half of the classrooms studied, including over 95 percent of classrooms in the all-air conditioned Central Valley school district, were supplied with outdoor air at levels below the state standard of 7.1 liters per second per person,” the study said. Ventilation rates measure the amount of outside air brought indoors, whether through natural ventilation, such as open windows, or mechanical ventilation, using ventilation system fans.

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