Method and apparatus for challenge distribution

A filter housing comprising:

• a housing having a top wall and one or more side walls defining an interior volume, wherein the housing is configured to position one or more filters;
• and
• one or more aerosol injectors having one or more walls defining one or more mixing chambers, and wherein the one or more aerosol injectors is one or more support struts of at least one of the top wall and/or one or more side walls.

A method of injecting aerosol in a filter housing comprising the steps of:

• providing a filter housing having one or more housing walls defining an interior volume and one or more support struts adjacent to and supporting the one or more housing walls, the one or more support struts include one or more openings therein;
• and
• injecting aerosol to the one or more support struts from an aerosol access port accessible from outside the filter housing.