Abstract: A vent assembly has a vent housing having a first axial end, a second axial end, and an airflow pathway extending between the first axial end and the second axial end. An environmental opening is towards the second axial end configured for fluid communication between an outside environment and an airflow pathway. An enclosure opening is configured to selectively define a fluid flow pathway between an interior of an enclosure and the airflow pathway. The vent assembly has an obstruction having a first relative position and a second relative position. The obstruction is configured to obstruct the fluid flow pathway in the first relative position and unobstruct the fluid flow pathway in the second relative position. Filter media is disposed in the vent housing laterally across the airflow pathway.