Stale Air Solution

Sick Yacht Syndrome – Clean Air for Yachts, Cruiseships

Norwalk Virus, bilge odours, flesh eating bacteria, mold, yeast, holding tank odours, VOC’s, stale air, diesel bacteria – all are indoor air problems on a yacht.

Why are indoor air problems magnified on a yacht and how can we control them?

sickyachtIndoor air problems or sick building syndrome is a widely recognized, universal health problem. What is new and gaining attention is Sick Yacht Syndrome. The indoor air problems of a home or office building are miniscule compared to the indoor air problems of a yacht. The problems with yachts or any vessel are numerous. By nature, just the fact there is a tightly sealed vessel in a dark, damp atmosphere with wide temperature differentials, and a wide array of mold, bacteria, odours and microbial food sources available leads to potential major indoor air health problems.

Stale Air – S.O.S. for S.Y.S.

Yachts are notorious for stale air. You can notice it as soon as you step onboard. There is a trademark odour. Some try to mask odours with another odour or scent. Companies actually specialize in “scent engineering”, tying certain scents with feelings or moods. The problem with this concept of olfactory persuasion is that we all process odours differently. Roses may smell good to you and make you smile, but may remind the next person of a funeral home! The best scent engineering is a non-scent or the absence of all odours. Routinely, hotels change drapes and bedspreads not due to wear, but rather the absorption of odours. This problem is amplified on a yacht due to the wide variety of odours. Yachts are tightly built. Space and weight are design problems. Therefore heating, ventilation and air conditioning (HVAC) equipment is kept to a minimum. Make-up air or fresh outside air is limited or non-existent.

Make-up air

Make-up air should represent 25% of a yacht’s airflow. Designers prefer to recycle the air as it is usually warmer or cooler than the outside air, so less energy is required to heat or cool the air. The problem is the same air is constantly being turned over. This is especially true in the lower staterooms. Assuming no one opens a port hole and each stateroom has its own air handler (heating/cooling unit) and two people are in a stateroom with the door closed, there is no fresh air circulating, just recycled air. This is true for the entire lower stateroom area. The only way to get fresh air down the stairway via Brownian motion or a very slow molecular air transfer. Trying to get fresh air down a stairway into closed staterooms is like trying to blow air into a bottle. The old air has no place to go so the area ends up with a static air situation. With all the airborne bacteria, molds, yeasts and VOC’s, this build up can cause very serious problems. Most bacteria are harmless, but when there is a build up of billions, it drastically increase your chances of exposure to a bad one.

Diesel Fuel

A yacht can carry anywhere from a few hundred to tens of thousands of gallons of diesel fuel. The fuel, of course, is confined to the fuel tank. Most yachts have a diesel fuel odour. Some are subtle, some are stronger. Assuming there are no leaks or spills, you will still get diesel odours from the fuel tank vents that relieve air pressure caused by fuel displacement of air and temperature variations. Fuel vents vent outside the boat. However, some diesel odours always seem to find their way inside the yacht, plus the engine room usually has many small leaks and venting. Why is this important to the yacht owner’s indoor air problems? Aside from diesel fuel odour being unpleasant, diesel fuel is a microbial breeding ground and food source. Diesel fuel has the ability to harbor and grow 30 types of bacteria, 12 yeasts and over 80 fungi species. When fuel odours are present, these odours actually represent minute aspirated fuel particles that can easily be carrying some of the bacteria, yeast or fungi known to grow in diesel fuel.

Bilge odours

All yachts have bilges, and with them come odours, oil, fresh water from air conditioner condensers, and soapy wash water. All are excellent breeding grounds for bacteria. Oil, like diesel fuel, contains bacteria, yeast and fungi. Soap and detergents contain phosphates, which can fertilize our lawns and gardens but can also fertilize microbial growth. As with diesel odours, bilge odours aspirate minute particles of bilge water loaded with microbial and food sources for the microbials.

Holding tank odours

Yes, sewage stored in a yacht holding tank can run from 50 gallons to over 5,000 gallons. Again, these tanks are vented outside of the hull, and are a huge source of bacteria, viruses, methane, and hydrogen sulfide gases, and of course, odours. These sewage gases, bacteria and odours always seem to find their way into the yacht, again providing microbials as well as food sources for the microbials themselves.


Molds are gaining worldwide attention. Multimillion dollar homes are being razed due to mold contamination. Insurance companies are excluding mold damage from their coverage. Mold spores are everywhere. They simply need still air, moisture and a food source. Yachts provide a perfect atmosphere for growing mold. Ideal food sources are leather, paper, fabric and wood. This combined with stagnate air and dampness produces a perfect mold farm. VOC’s or volatile organic compounds are a common indoor air problem as they are everywhere: cleaning compounds, plastics, furniture, etc. All are found on a yacht. However, a yacht will have much higher levels of VOC’s then a home due to all the glues, sealants, oils and fuel. A fiberglass vessel will be continuously off gas VOC’s. Lysteria Monocytogenes is a unique strain of bacteria that can live in a very cold atmosphere and is often found in sink and shower drains and ice makers. When food poisoning breaks out in a restaurant and nearly everyone gets sick, it is usually from the ice machines lysteria bacteria. Most patrons are served ice and water or ice in a drink. Lysteria loves yachts – lots of ice machines, lots of drains and shower sumps to grow in. Drains, shower sumps and heads also add to the yacht odour and overall bacteria problems. Norwalk Virus represents a very serious problem to the cruise and yacht industry. Thousands have been infected and many cruises cut short. Why is Norwalk so prevalent on a ship? Norwalk is most likely transferred by surface to hand contact in a confined environment. It is very difficult to contain. Disinfect surfaces or wash your hands frequently.

Advanced Oxidation Process

A new technology that uses friendly oxidizers to oxidize (kill) mold, viruses, bacteria, yeast, VOC’s and smoke into harmless CO2 and water. By friendly oxidizers, we mean oxidizers that turn into safe oxygen and hydrogen when the oxidation or kill occurs. Advanced oxidation or AOP cells create gases and ions such as hydro-peroxides, superoxide ions and ozonide ions. These aggressive gases are developed by targeting a high intensity UV light on a precious metal target. Unlike ozone generators, advanced oxidation systems use redundant safe oxidizers and are widely used by all major food processors, the military, major cruise ships, homeland security, hospitals, assisted living facilities, hotel chains, etc.

Wastewater Related Diseases and Viruses from Inhalation*

*Water Pollution Control Federation

• Tuberculosis
• Histoplasmosis
• Coxsackie A&B
• Adenovirus

• Bacteria Dysentery
• Common Cold
• Echovirus
• Rotavirus