According to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), proper ventilation for prevention of COVID-19 particles requires filters with a rating of MERV 13 or higher. All classrooms in the West Linn-Wilsonville School District have ventilation filters that exceed the MERV 13 rating, with the exception of some select classrooms in the district’s oldest schools. Those classrooms have been equipped with HEPA Filters, which are more efficient than MERV 16 filters.
To ensure adequate air flow and ventilation in classrooms, outside air intake has been adjusted to maximize the amount of outside air. Currently, systems are set at 50% outside air, which is adequate to achieve four air changes per hour, more than recommended by ASHRAE.
Ventilation is more difficult in large, open spaces such as gymnasiums. In those areas, the district has increased outside air intake as much as outside temperatures will allow. This is in alignment with ASHRAE and Ready Schools, Safe Learners recommendations.
Temporary ventilation systems are currently in place at certain school sites while capital bond construction projects wrap up this summer and early fall. Ventilation systems were upgraded at multiple school sites this summer through capital bond prjoects. Ventilation meets all ASHRAE, OHA, and CDC standards at all schools.