Before school buildings opened in September 2020, ventilation systems in every classroom throughout the city had been inspected, updated and repaired as needed. Each classroom in use should have adequate ventilation through either natural or mechanical means or a combination of the two. In addition to the upgraded ventilation systems introduced last school year, each classroom has been equipped with two air purifiers. Cafeterias in bigger schools have large air units for added protection and window-based exhaust fans to provide additional air circulation. These measures meet or exceed guidance from the U.S. Centers for Disease Control and Prevention.
Natural Ventilation During Extreme (Hot or Cold) Outside Temperatures
If you rely on open windows for good ventilation in your classroom, you will need to keep a few windows cracked open a few inches even though it may be cold or hot outside. The good news is you can open fewer windows because of the laws of physics.
The temperature difference between warm air inside and cold air outside actually creates better movement of the air. The colder it is outside, the better the air exchange.
For best results:
- Open two to four windows from the top about 3 inches.
- Have the custodial engineer check the temperature and carbon dioxide levels in your classroom if it’s just too cold to leave windows open that amount.
- Keep the top and front of radiators clear to allow proper heat circulation.
For questions about building temperature or your school's ventilation system, see your chapter leader or call the UFT at 212-331-6311.
Carbon Dioxide Measurements
ASHRAE has issued the most comprehensive set of recommendations for indoor air quality in the document 62-1989, "Ventilation for Indoor Air Quality". ASHRAE recommends that the ventilation system provide 15 cfm (cubic feet per minute) of outside air per person in classrooms.
A good indicator of inadequate ventilation in a school or office building is the level of carbon dioxide. Carbon dioxide is a gas present in the outside air at levels of around 300 to 400 parts of carbon dioxide per million parts of air (ppm). Since people exhale carbon dioxide, indoor air levels of carbon dioxide increase when the ventilation does not supply adequate outside air. ASHRAE has recommended that a level of 1,000 ppm carbon dioxide be used to indicate a supply of 15 cfm of outside air per person.
The UFT has distributed carbon dioxide (CO2) monitors to its district representatives and chapter advocates; each school custodian also has one. These portable devices measure the CO2 that people in the room exhale. A room without adequate ventilation will show CO2 levels that are higher than 1,000 parts per million. If you are concerned that your classroom or workspace does not have proper ventilation, you should request a reading. Fixing the problem can be as easy as opening more windows and ensuring that vents are not blocked and the ventilation system is working. If that doesn’t solve the problem, call the union’s Safety and Health Department for help.