This study examined the particle collection efficiency of a natural fibre filter media in order to determine the suitability of a natural fibre filter to substitute current filter media. Current filters are predominantly petroleum based, and when these filters reach the end of their life, are sent into the refuse stream. Natural fibre filters, alternatively, are environmentally produced, sustainable products that will be biodegradable at the end of their life. A testing chamber was constructed to follow the ASHRAE 52.2 Standard, at Delta M Incorporated in Milton, Ontario. However, due to limitations of equipment availability and funding, for this study, some adjustments were applied to the chamber characteristics outlined by the Standard, which through verification testing, still qualified the chamber for testing. The natural fibre filter media types that were tested included flax, 300 gsm, 450 gsm and 600 gsm, and hemp, 500 gsm and 750 gsm. The testing procedure, unlike the chamber development, followed the methodology outlined by ASHRAE 52.2 Standard, to find the minimum efficiency reporting value (MERV) rating of the fibre media. Both flax and hemp filters performed well in comparison to the current filters in residential and industrial applications, reporting a minimum MERV of 8, and a maximum of 11. It was found that the particle capture efficiency was higher for mid-range particles, 1.0 to 3.0 μm, than for larger particles, 3.0 to 10.0 μm, which was attributed to the natural fibre characteristics. In order to commercialize this project, it is critical to assess the outstanding issues of flammability and mould resistance. Additionally, it is recommended to obtain a larger variety of natural fibre filters, for both natural fibre type and weight density, to optimize the particle capture efficiency and air resistance to produce a final natural fibre filter.