A recent outbreak of Covid-19 in a Philadelphia area school has administrators scrambling to find a cause. There was significant in-school transmission of the virus but there was also a perplexing element to this case – all of the infected students were in only one classroom. Officials wondered what was so different about that one particular classroom? A full investigation lead to the discovery of a possible factor. A damper in the ductwork above the classroom was almost completely shut letting in only about 30% of the usual fresh air that would be circulated. According to a district spokesperson the damper that was closed could only be seen by actually looking inside the duct and that the monitoring system in place gave no indication anything was wrong. A case like this underscores how important ventilation in school really is. How many other schools have dampers shut above classrooms that no one can see?

What should everyone be doing right now to improve ventilation in schools?

One of the simplest and most cost effective things to do right now is inspect. In order to do that though, you need individuals who are qualified and trained in indoor air quality and ventillation systems and know what to look for. The CDC recommends making sure ventilation systems are serviced up to ASHRAE standard 62.1. The CDC also recommends reducing or if possible, eliminating air recirculation with the assistance of an expert HVAC consultant.

In the case above, the school had commendably tried to improve the air systems by adding MERV-13 filters to the air handling units but failed to understand how the system worked as a whole. Each part of the ductwork should have been manually inspected and visually verified but you have to know what to look for in order to check. Upgraded filters don’t help kids in classrooms that the fresh air never reaches.

In addition, we are seeing that univentilators need cleaning and need serving as well. These are smaller units, typically one in each classroom to provide heat, AC, and fresh air. These units need to be cleaned, filters changes and serviced so they are functioning properly.

Here are some recommendations from ASHRAE:

• Provide and maintain at least required minimum outdoor airflow rates for ventilation as specified by codes and standards
• Use combination of filters and air cleaners that achieve MERV 13 or better for recirculated air
• Maintain temperature and humidity design set points
• Maintain clean air supply required for occupancy
• When necessary flush spaces between occupancy

For more information on this go to ASHRAE.ORG, they have some guidance documents and copies of the ventilation standards.

Insurance Restoration Specialists, Inc. (IRS) is a premier provider of disaster recovery mitigation, environmental remediation, biohazard emergency response and HVAC inspection and cleaning in the New Jersey-Philadelphia area. IRS is certified by NADCA and have Certified Air Systems Cleaning Technicians and a Certified Ventilation System Inspector on staff. Services include mold removal, water damage restoration, fire damage restoration, flood damage cleanup, smoke damage remediation, and biohazard remediation. Insurance Restoration Specialists is led by Certified Industrial Hygienist Thomas Peter.