Healthy Schools Need Healthy Air

When we think about pollution and wonder about the air we’re breathing, we usually think about the outdoors. A cover of black smoke from wildfires or factory chimneys. Dirty exhaust shooting from the tail pipe of an old car. As a new working paper by the Center on the Developing Child at Harvard University points out, “the importance of outdoor air quality for health has long been recognized.” 

Less recognized has been the impact of the air we breathe indoors, even though we spend about 90% of our time inside, says Lindsey Burghardt, one of the authors of Air Quality Affects Early Childhood Development and Health and the center’s chief science officer. As co-author Joe Allen, an associate professor of exposure assessment management at the Harvard T.H. Chan School of Public Health, said at a recent webinar to discuss the paper, “We’re an indoors species.”

It was the COVID pandemic that drew public awareness to how much the indoor environment influences the spread of disease, Burghardt says. “Joe mentions this in his book, Healthy Buildings, but many of us have always sensed how indoor environments affect how we feel. When we enter a beautiful office space we think about how good it makes us feel; when we enter a dim or stuffy one, we instinctively sense the opposite feeling.”

Indoor air affects everyone, of course, but as the paper points out, the impact is especially concerning for babies, children, and students. 

“Not only are young children exposed to more indoor air pollutants,” write the authors, “but they are also more affected by this pollution than most adults because they breathe more rapidly, they inhale a larger volume of air relative to their body size, and their respiratory, reproductive, endocrine, immune, digestive, and neurological systems are still developing, making them especially sensitive to exposures.” Harmful air has the potential to adversely affect development, health, and learning.

According to the paper, particles and chemicals floating in the air pass through the lungs and into the body, triggering the immune system to respond. While inflammation protects the body, too much inflammation for too long can actually weaken the immune system, especially if it happens while children’s organs and brain are still developing.  These pollutants, the paper points out, “disproportionately impact families with fewer resources and families of color due to discriminatory housing and zoning practices and other barriers to accessing affordable, healthy housing.”

Pollutants are also prevalent in our schools, where kids will have spent about 15,600 hours by the time they graduate high school, Burghardt says.

“The type of pollutant found in schools depends both on what is inside the school building (indoor sources of air pollution),” she says, “the ventilation in the school (the exchange of air inside the school with the air outside), what surrounds the school outside (the outdoor air environment surrounding the school), and the degree that the outdoor air can get inside (how “leaky” the school is).” 

Carbon dioxide, for example, is produced by everyone breathing inside a building; in schools, levels can be especially high. Standards set by the American Society of Heating, Refrigerating, and Air-Conditioning say CO2 levels should be less than 1,00 parts per million (ppm). In schools across the country, “it’s common to find CO2 levels above 1,500 ppm or higher,” says Burghardt. “If you’ve ever become sleepy while driving in a car for long distances, this is in large part because of the CO2 buildup inside of the vehicle. When ventilation is poor in classrooms, CO2 builds up. Cognitive testing in students shows a 5% decrease in the ‘power of attention’ in poorly ventilated classrooms; in that study, that difference is equated to the same effect as kids skipping breakfast.”  

Other factors also affect air quality in schools, including chemicals released from synthetic carpets and fabric, flame retardants used in building materials, scented cleaning products, and phthalates chemicals that make plastic bendable and are found in vinyl tiles and PVC piping. Dust mites and mold, as well as cockroaches and mice, can also negatively impact breathing. In the United States, almost 1 in 13 children have asthma. “Asthma is the leading cause of missed school related to chronic illness,” Burghardt says. “An abundance of scientific evidence links indoor exposure to these contaminants with worsened asthma symptoms, and these allergens are very prevalent in school. They also affect student performance as well as staff and teacher performance and health.”

Pollution from the outdoors can also “leak” into schools, especially in older buildings and those located near busy roads or industry. Wildfire smoke enters through invisible cracks and air ventilation systems without high-quality filters. As the working paper points out, recent wildfires have been “a major threat to the health and development of young children,” with their “potent mixture of fine particles, black carbon, and chemicals such as carbon monoxide and nitrogen dioxide.”

The good news, says Burghardt, is that changes can be made to make classrooms healthier for students. Schools can upgrade purifying filters and control dust, for starters. They can better monitor and measure indoor air. In 2022, for example, Boston Public Schools installed indoor air quality sensors across the district. The sensors measure air particles, carbon dioxide, and carbon monoxide in classrooms and have allowed schools to quickly identify and respond to indoor air quality issues in real time. Schools can also avoid purchasing products and building materials that contain harmful chemicals and use portable, room-based air purifiers with HEPA filters, which are relatively inexpensive, but make a big difference in improving air quality for students and school staff. 

Polluted air in schools is fixable, says Allen. “I chased sick buildings for years,” he said in the webinar. “It doesn’t take much to turn sick buildings into healthy buildings.”