HONDA Pollen Filter. When breathed in, particles smaller than approximately 2 microns are absorbed into the lower respiratory tract and lungs and cannot be expelled by exhaling: they remain as deposits. The superiority of Honda Genuine Cabin Filters : 3 layers in comparison with other products. Due to these 3 layers the Honda Genuine Cabin Filters have been specially designed for each particular model of vehicle to ensure that dust, pollen and other contaminants cannot flow through to the evaporator via air gaps. Filter types to suit the characteristics of each region are used. Designed with a proprietary filter paper with air holes that trap fine dirt and dust (the area of the filter differs with model). Long operating life thanks to a proprietary filter paper material and structure