Resources

Ventilation

“Dilution is the solution to pollution.”
Ventilation is simply the process of bringing outside air to inside locations. When we breath, we inhale oxygen and exhale carbon dioxide (CO2). Outside air has a CO2 concentration of around 400 parts per million. With poor ventilation, inside carbon dioxide levels will rise. Ventilation can be achieved with an HVAC system or even by opening doors and windows.

Table 1. Additional benefits of higher ventilation and improved air quality in schools beyond airborne infectious disease transmission.
Impact of Ventilation	Context	Findings	Reference
↑ Test Scores	Ventilation renovations were completed to improve IAQ in all school buildings within a single Texas school district.	Math and reading test scores significantly improved, with an increased probability of passing by 2% and 3%, respectively.	42
↑ Cognitive Function	CO² concentrations were measured as a proxy for ventilation rates in classrooms.	Math and reading test scores significantly improved, with an increased probability of passing by 2% and 3%, respectively. Cognitive testing of students shows a 5% decrease in ‘power of attention· in poorly ventilated classrooms. Researchers equate this to the effect of a student skipping breakfast	38
↑ Math, reading, and science scores	Classroom ventilation rates were measured in 140 fifth grade US classrooms.	Mean mathematics scores increased by up too. 5°/4 per each liter per second per person increase in ventilation rate, with similar effects on reading and science scores.	43
↓ Asthma symptoms	Exposure factors were measured in 100 primary and secondary school classrooms with and without new ventilation systems.	Pupils who attended schools with new ventilation systems reported fewer asthmatic symptoms.	44
↓ Respiratory symptoms	Over 4,000 sixth graders from 297 schools participated in a survey of indoor environmental quality in schools.	Lower ventilation rates, moisture, and dampness were all independently associated with a higher incidence of respiratory symptoms. Inadequate ventilation was also associated with more missed school days.	45
↓ Missed school days	Increased ventilation rates and child sick days were studied for 635 children attending 20 day-care centers in Denmark.	A 12% decrease in sick days was found per hour increase in the air exchange rates.	46
↓ Child absenteeism	CO² as a proxy for ventilation was studied in 60 naturally ventilated primary school classrooms in Scotland.	For each 100 ppm increase in time average CO² concentration, student attendance decreased by about 0.4 days per year.	47
↓ Illness absence	CO² concentration was measured continuously over two years in 162 US primary school classrooms with a mixture of mechanical and natural ventilation.	For each 1 L/s (2.2 cfm) per occupant increase in ventilation rate, illness absence decreased 1.6%.	26

Filtration

“Cleaning the air”
Filtration is the process of “cleaning” out things from the air such as allergens, pollution, bacteria, and viruses. Common air filter types include MRV, HEPA, and the easily accessible and cost effective Corsi-Rosenthal boxes.

Hepa Filter Buying Guide:

CADR (higher number = better filtering)

CADR 520: Smart Air Blast (quiet 40 decibels)
CADR 460: Colzer KJ800 (louder 65 decibels)
CADR 400: Inofia PM1608 ((louder 65 decibels)
CADR 350: Conway Airmega 400 (quiet 50 decibels).
Small portable hepa filter for personal use on the go

How to Monitor

You can monitor classroom (or school bus) ventilation with a CO2 monitor. There are many options available. ASHRAE recommends the Aranet4. https://shop.aranet.com/product/aranet4-home

How to Improve AQ

Improving air quality can be as simple as opening a window or door to improve ventilation. For filtration, we recommend the highly effective and affordable Corsi-Rosenthal Box. The video below gives step-by-step instructions on how to construct a Corsi-Rosenthal Box.