Cannabis Air-borne Particle Size Chart


Cannabis air quality is becoming an increasing area of focus for indoor growers because of contaminated batches and recalls. Whether operating in climate-controlled greenhouse or warehouse, air filtration is an important part of securing the biological, microbial, and food safety of your cultivation operation. The challenge is determining the ideal type, size, and placement of any cannabis air filtration system. Systems can vary from insect netting sized for specific pest pressure to HEPA rated filtration systems for post-harvest compartments.

Yellow Aphids

Volumetric Flow Rate

One of the largest factors influencing filter design is the volumetric flow rate expected to pass through the filter. Filters are typically placed in-line of any Heating, Ventilation, and Air Conditioning (HVAC) system. Therefore, specified ventilation flow rates are determined by a mechanical design engineer and specified in cubic feet per minute, (CFM).


MERV Rating

Another critical factor that affects cannabis air filtration design is the Minimum Efficiency Reporting Value (MERV). MERV was developed by the American Society of Heating, Refrigeration and Air Conditioner Engineers (ASHRAE). The standard values vary from 1 to 16 as indicated at the bottom of the chart. The higher the MERV value for a filter, the more efficient it is at trapping airborne particles.

Powdery mildew on a cannabis leaf

This airborne particle size chart is meant to simplify air filtration design decisions for indoor cultivators. It demonstrates the relative size of relevant airborne contaminants like pests, dust, pollen, mold, and bacteria. This chart was created for growers by referencing the ANSI/ASHRAE Standard 52.2 for air filtration. This document also reinforces the thoughts shared by the National Filtration Association with regard to cannabis air filtration.


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