June 6, 2013
Improving Ventilation In Schools Could Reduce Illness-Related Absences
redOrbit staff & Wire Reports — Your Universe Online
Making sure that students get enough fresh air in their classrooms could keep kids from missing school due to illness, researchers from the at Lawrence Berkeley National Laboratory (Berkeley Lab) claim in a new study.
Writing in the journal Indoor Air, lead author Mark Mendell and his colleagues report that their analysis of over 150 California classrooms revealed that bringing classroom ventilation rates up to state standards could reduce illness-related absences by about 3.4 percent.
Mendell and his colleagues collected data from 162 third- through fifth-grade classrooms in 28 schools across three different California school districts. They found that over half of those classrooms failed to meet state ventilation standards.
It would take an investment of approximately $4 million each year to make the necessary upgrades to reach those standards, but by doing so, they say that California´s school districts would gain an additional $33 million in attendance-related funding — and families could avoid upwards of $80 million in caregiver costs due to sick children missing school.
“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,” Mendell, an epidemiologist at the Berkeley Lab´s Indoor Environment Department, said in a statement. “It´s really a win-win situation.”
Under California state building codes, schools are required to provide a ventilation rate of 7.1 liters per second per person, or about 15 cubic feet per minute per person. The ventilation rate, the researchers explain, is a flow rate that measures how much outside air in brought indoors via open windows, ventilation fans, or other means.
Mendell´s team found that ventilation rates “varied widely” within schools and districts, as well as from one district to another. Portable classrooms tended to receive less ventilation, and schools located in the Central Valley of California -- a region susceptible to extreme weather conditions in both the summer and winter -- tended to rely upon heaters and air-conditioners and were below state ventilation standards 95 percent of the time.
The school districts provided information on daily absences due to illnesses in each classroom, and the researchers then calculated ventilation rates based on carbon dioxide levels as measured indoors and estimated outdoors. Indoor CO2 levels were based on environmental sensor readings from each classroom — data that was transmitted to the research team via the Internet.
“The overall finding from all three districts was that for every additional 1 liter/second/person of ventilation provided to a classroom, illness absence declined by 1.6 percent, with the benefit continuing at least up to 15 liters/second/person, more than double the state standard,” officials with the Berkeley Lab said.
That data was extrapolated based on two assumptions — first, that the findings represented true causal relationships, and that all California K-12 classrooms had the 4 liters/second/person average ventilation rate, which had been estimated from carbon dioxide data obtained as part of a previous state-wide survey.
The authors calculated that upgrading all schools to the state standard of 7.1 liters/second/person would not only reduce illness-related absences by 3.4 percent, it would increase overall state funding by $33 million under a program that provides schools with approximately $30 per day in funding for every student in attendance on that day.
“Further increases in ventilation rates, at least up to 15 liters/second/person, would result in additional benefits“¦ such as reduced costs related to sick leave for teachers and staff and reduced health care costs for students,” the laboratory said. “They also noted that, in most parts of California, replacing ventilation equipment would probably not be necessary to increase the ventilation rates.”