Schools - White Paper Delos

Current Indoor Environment Conditions in Schools and Opportunities for Improvement

While schools nurture the minds of our next generation, they also present a largely untapped opportunity to promote health and well-being. On average, children in the U.S. spend about six hours per day, or 1,000 hours per year in school. Elements of the indoor environments where students, educators, and staff spend a large amount of their time can have an impact on their overall health. At Delos, we set out to research what makes a healthy learning environment. A few takeaways were surprisingly simple, easy to implement, and have the potential to provide a lasting impact. Read on to learn more!

Educational environments play a critical role in helping students learn, shaping their everyday experiences and affecting their development, health, and overall well-being. Children and adolescents spend a large portion of their time inside school buildings, during a period of their lives when they are especially vulnerable to environmental influences on their development. In fact, time spent in learning environments is second only to time spent at home for this age group. By the time a typical student graduates from high school, they will have spent more than 15,000 hours of their life in school.

How can we optimize the learning environments in which the next generation will spend a quarter of their waking hours?


Recognizing Current Indoor Conditions in Schools

The current conditions and physical state of many learning facilities are far from optimal, with different factors at play. First of all, school density is higher than that of many other types of buildings; in fact, a typical school has about four times the number of occupants as a typical office building for the same amount of floor space. More occupants per square footage of space means greater levels of carbon dioxide generated through breathing; less physical space as well as more frequent and closer interactions between people, which can contribute to the spread of respiratory infections and illnesses; and more wear-and-tear of the building itself, making it “age” faster. Second, many school buildings are old. As of 2012, the average age of U.S. public school buildings since the time of construction was 44 years, and the average age since renovation was 12 years. Buildings that are old are more likely to have issues that can negatively impact student health: they may not adhere to more recent building standards and best practices, and conditions can deteriorate without extensive preventive maintenance. Furthermore, up to a third of public schools lack basic maintenance and are in poor shape: among schools with permanent buildings, 14 to 32% rated their building systems/features as being in fair or poor condition.

Many schools also use temporary buildings due to funding limitations and fluctuating enrollment levels. Many of these temporary buildings have suboptimal conditions that present challenges with respect to healthy environments. In fact, among public schools with portable (temporary) buildings, the building systems/features were rated as being in fair or poor condition in their portable buildings in 29 to 45 percent of the schools.

Common physical issues in school buildings include:

  • mold problems;
  • unhealthy building materials;
  • outside air seeping indoors;
  • lack of windows and inadequate or poor lighting;
  • poor drinking water quality;
  • absence of or unreliable AC and heating systems;
  • inadequate ventilation and filtration systems;
  • inadequate insulation to protect from outdoor noise; and
  • disconnection from nature.

Thus, many students spend the majority of their waking hours in poor-quality environments, over a period of 12 or more years. Unsurprisingly, unhealthy or sub-optimal learning environments have been associated with poorer health and performance outcomes, such as asthma and allergy symptoms, slower recovery from stress and mental fatigue, headaches and concentration issues, learning problems, and lower test scores, among others.



Children Can Be Especially Vulnerable to Unhealthy Physical Environments

During early childhood, a rapid and extensive development of organs and systems takes place — which makes this period critically important to a child’s future health. Young children have an increased hand-to-mouth activity and spend more time on the floor as well as touching things around them, which can increase their exposure to harmful chemicals. Younger children also consume more air, food, and water relative to their body weight, which increases the relative dose of potentially toxic exposures. The fragility and plasticity of younger childrens’ organs and systems leaves them vulnerable to harmful influences and disruptions that may affect their future function.

It is also important to note that children’s natural defenses against potential toxins are less developed than they are in adults, meaning that children are more likely to be harmed when exposed to pollutants. This is because children have highly permeable skin, lower filtration efficiency in their nasal passages, a more permeable blood-brain barrier, and not yet fully-developed organs and processes (e.g., digestive system and kidney clearance) that are involved in defending the body from toxins and pathogens. Developmental processes and sensitivity to sub-optimal environmental conditions carry on beyond early childhood, as children and adolescents continue to grow physically and develop psychologically throughout their years at school.

The bright side is that because the physical environment has a significant influence on children, schools have a unique opportunity to positively impact students by creating safer, healthier, and enjoyable learning environments that enable kids to thrive in their health, well-being, and academic performance.

Ensuring Healthier School Environments for All
It is important to note that not all students experience poor learning environments to the same extent. Low-income schools and schools serving Black, indigenous, and people of color (BIPOC) students are more likely to have unhealthy conditions due to significantly lower funding compared to schools with a predominantly white student population, and because they are often located in neighborhoods with poorer air quality and greater levels of noise. For example, based on a study of nearly 85,000 public schools (grades K-12) across the United States, students from racial/ethnic minorities disproportionately suffer from exposure to air neurotoxicants in school. In addition to posing health risks, this can also impact school performance and future potential. It is not just students that are negatively affected but also educators and staff — due to factors beyond the physical school environment. For example, teachers in schools that are located in low-income neighborhoods more often report occupational burnout, and take more long-term sick leave. While it may be difficult to meaningfully modify neighborhood environments and social inequality, schools themselves can and should be improved.

The physical environments of schools have the potential to make an enormous impact on the health, performance, and well-being of millions of children, adolescents, teachers and staff in the U.S., and hundreds of millions throughout the world. By working to improve the quality of our learning environments, we can help students achieve not only their full academic potential but also help ensure they are healthy, happy and well throughout their learning years.


Education and Covid-19: How Delos Is Helping to Advance Health and Safety in America’s Schools

Small aerosolized particles carrying SARS-CoV-2 (the virus that causes Covid-19) can remain suspended in the air and persist in aerosol form for long periods of time indoors. Therefore, air purification systems are considered by many to be a critical supplementary approach to reducing transmission rates by remediating airborne pollutants and contaminants. While schools have taken significant measures to address surface and behavioral viral load though extensive cleaning protocols, social distancing and mask wearing, to name a few, the critical aspect of airborne viral transmission remains largely unaddressed.

Recognizing the need for research-backed solutions across the education sector, Delos is collaborating with schools and universities around the globe to integrate air purification and other solutions in response to Covid-19. In fact, to-date, Delos has provided over 150,000 Delos Compact air purification units to schools across the country, along with evidence-based recommendations on necessary measures for safer school reopening. Our clean air technology is trusted by some of the largest school districts in the U.S., including the NYC Department of Education, Chicago, Miami-Dade County, Boston, Baltimore, and Portland Public Schools. Delos Compact units capture ultrafine particles as small as 0.007 microns, and can reduce particles that carry airborne bacteria and viruses at 99.99% efficiency1. It also removes 99.997% of particles 0.3 microns in size, which is more efficient than HEPA Standard testing efficiency requirement2. Furthermore, the Delos Compact units have a 6-stage VOC adsorption filter for removal of harmful gases and odors. Finally, the portable nature of these air purification units provides a scalable, implementable, and highly efficient solution, as they do not require schools to undergo heavy renovations or upgrades to their aging buildings and existing HVAC systems.


Schools - White Paper Delos


We hope that adding portable air purification units to classrooms across the country will help to boost the confidence of students, parents, teachers and staff that it is safe to return to school. Even further, we hope that it will be an investment beyond Covid-19, leading to enhanced cognition and performance due to improved air quality. To aid this initiative, on December 27, 2020, the Coronavirus Response and Relief Supplemental Appropriations Act (CRRSA) was signed into law to further support schools nationwide. The CRRSA has distributed a total of $54.3 billion nationwide that can be used to implement strategies for improving the indoor air quality in elementary and secondary school facilities – in addition to the $30.8 billion previously provided to schools under the Coronavirus Aid, Relief, and Economic Security (CARES) Act. The CRRSA also provides over $4 billion in funding, which is available through the Governor’s Emergency Education Relief (GEER) fund, to help support students of all ages and at all schools. The GEER fund specifically allocates $2.85 billion to Emergency Assistance to Non-public Schools (EANS), which can be used to help improve the quality of indoor air in non-public schools.

“We hope that in conjunction with current Covid-19 mitigation strategies, these solutions will benefit not just the students and staff, but more broadly the families and communities they serve,” said Delos Founder and CEO Paul Scialla. “Ultimately, we hope that school systems around the world will follow the model example set by each of these schools, prioritizing cleaner air and healthier learning environments.”


What some of our customers are saying:

“It’s about providing peace of mind; for our teachers, students, and staff. Delos helped us get there.”

– Karl Ertle
President, Walsh Jesuit High School


To learn more about the indoor environmental factors that affect student health, well-being and performance, and the steps schools can take to address these factors, make sure to check out our white paper Healthy Learning Environments. To explore our air purifiers, check out the Delos Shop.


Edited by: Radhika Singh


1 Individual particle sizes and specific particle size ranges may have different filtration efficiency rates
2 EN-1822 testing of the Intellipure Compact device operating at 150 CFM