Tri-Dim Filter Corporation
Manufacturer of many types of HVAC air filters and general ventilation products.
http://www.tridim.com/

Glasfloss Industries
Learn about air filters and air filtration systems offered by Glasfloss Industries.
http://www.glasfloss.com/

Mine Ventilation Services, Inc.

http://www.mvsengineering.com/

Lunor
Lunor G. Kull AG - Produktion und Dienstleistungen in den Bereichen Entfeuchtungssysteme und Schutztechnik.
http://www.lunor.ch

FIT Ventilation
FIT Ventilation - Your source for affordable portable ventilation.
http://www.fitventilation.com

Schaefer Ventilation
Ventilation and circulation fans for the greenhouse industry.
http://www.schaeferfan.com/Horticultural_Ventilation_C264.cfm

Vostermans Ventilation B.V.
Vostermans Companies is the parent company of a multinational enterprise, founded in 1952. Vostermans Ventilation B.V. Vostermans Alu Foundries B.V. Vostermans Tooling and Prototyping B.V.
http://www.vostermans.com

Smoking and Ventilation Standards
Americans for Nonsmokers' Rights (ANR) works to pass legislation at all levels of government to protect nonsmokers from secondhand smoke and protect youth from tobacco addiction. The American Nonsmokers' Rights Foundation (ANRF), ANR's educational arm, promotes smoking prevention and education about smoking, passive smoke, and the tobacco industry.
http://www.no-smoke.org/getthefacts.php?dp=d20

Tyder Ltd
Provides digital filter design software which can produce specialised filters e.g. Windowed FFT, Optimal FIR filters, and IIR filters.
http://www.tyder.com/

Simple Filters
Easy to use filters for enhancing Photoshop and Paintshop Pro - Not available anywhere else!!!
http://www.btinternet.com/~cateran/simple/