Evaporative Cooler Air Quality:
Problem & Solution
Anyone who has lived in the Southwest United States has had the unpleasant experience of breathing evaporative cooler air with a "fishy” smell. In August 2000 Anode Systems Company, a manufacturer of pollution prevention systems in Grand Junction, Colorado financed a study to determine what causes evaporative cooler air odor. Ms. Jennifer Eddies a microbiologist was contacted to collect water and fiber samples from four evaporative cooler pans and pads in Grand Junction. The samples were collected at (1) Mesa State College (2) School District 51 Administrative Office and (3, 4) Anode Systems Company Offices. The Samples were cultured to determine exactly what species of fungi and bacteria live in the local coolers and just how prevalent they are.
The cooler at Mesa State College was particularly offensive and found to contain large amounts of Bacillus species and Pseudomonas species bacteria in the pads. These are common bacteria found in soil and water, and can cause disease in humans. Moderate amounts of Corynebacterium species, Acinetobacter Iwoffi and Coagulase Negative Staphyloccus bacteria were present in the water. These are widely dispersed and found commonly on human skin. Acinetobacter Iwoffi bacteria can also cause disease in humans.
Of the three remaining coolers tested two had been equipped with Sunflower Zinc Anodes throughout the year. None of the three coolers had a noticeable odor. Culture tests were performed on water and fiber samples. Moderate to small amounts of Bacillus species Pseudomonas species Corynebacterium species and Acinetobacter Iwoffi bacteria were found in the District 51 and office complex coolers. Small to moderate amounts of Scopulariopsis species of fungus (mold) was identified in the office complex coolers. This rapidly growing fungus is commonly found in soil and can cause sinus problems in humans. It rarely causes infections in humans but can cause infection in people with low resistance to disease or a weakened immune system. Its colonies are gray to gray-black in color, which can be seen, in the wood fibers of the cooler pads. Each cooler tested negative for Legionella bacteria, which is the bacterium responsible for causing Legienellosis or Legionaire’s Disease.
Scientists have identified more than l00,000 species of fungi. The most common include molds and mildews. Common fungi seen as mold on bread cheese or fruit reproduce by releasing spores from the fruiting bodies much like the seeds from dandelion flowers. Two conditions essential to the growth of biological pollutants are nutrients and moisture. Warm standing water in the pans and moist pads can be a breeding ground for these microorganisms which become airborne and inhaled when the fan is turned on. Ms. Eddins believes that the “fishy” smell may be caused by a combination of these bacteria and fungus (mold) or yet unidentified microorganisms in moderate to large amounts.
Human immune systems normally kill small amounts of harmful fungus mold spores bacteria and the toxins (poisons) produced by them. However when large concentrations overwhelm the immune system’s ability to kill the invading harmful fungi and bacteria, they can trigger allergies, asthma attacks, headaches, nausea, dizziness and respiratory disease such as pneumonia. Poor air quality from biological air pollution causes lowered productivity, morale and health in the home, school and workplace.
In response to the problem of “fishy” smell Anode Systems developed an anode to inhibit the growth of these microorganisms. It is made of a zinc alloy and is called the “Bon-Aire.” When placed in the cooler pan water and grounded to the steel cabinet, a weak battery is created between the zinc and steel and an electro-chemical reaction takes place with the zinc. Zinc oxide, a known biocide and fungicide is created through oxidation of the zinc and is released into the water where it impregnates the wood fibers in the pads. Zinc oxide is a natural antifungal and antibacterial ingredient used in many over-the-counter medications sold in stores to heal and prevent diaper rash, athlete's foot and itch. Zinc is used to control fungus on roofs without being harmful to plants or animals. Zinc oxide will also control the growth of fungi, mold, mildew, and bacteria in cooler pads and cooler pan water. Antifungal ingredients like zinc oxide are used to protect fruit trees, grapevines and vegetables against mildew.
When the Bon-Aire zinc oxides are created, the anode releases electrons via a wire that is grounded to the steel cabinet. The electrons prevent corrosion of the steel pan and the creation of rust, which is the food supply for Crenothrix bacteria known as iron bacteria. If there are no antibacterial biocides in the water, iron bacteria combines oxygen and iron to produce a corrosive reddish-brown slime with a foul smell. If the cooler water stagnates, sulfate-reducing bacteria will digest the sulfates common in drinking water and produce odors similar to rotten eggs or sewage. Both of these reactions cause further corrosion of the cooler equipment and adds to the problem of foul smelling air. If a person can smell a “fishy” odor, they are inhaling fungi spores, bacteria and byproducts of nongreen plants like mildew.
It is important to note that only zinc oxides from zinc anodes inhibit the growth of bacteria, fungus, mold, and mildew that live in cooler water. Oxides from magnesium anodes do not inhibit the growth of these microorganisms.
By lowering the amount of these biological pollutants in an evaporative cooler the ventilation and quality is improved. With freshened and cleaned air, the incidence of allergies, headaches, nausea and asthma is reduced. This makes people at home in school and the workplace healthier, happier and more productive.
Additional information on the Sunflower Zinc Anodes, Anode Systems Company or the author Hans Schmoldt cart be found at www.anodesystems.com.
April 17, 2001