Now, what can you do about it?
- Stop the source. Most mold problems are created by some type of roofing, waterproofing, plumbing or mechanical problem. Mold needs water to proliferate. Repair the source of the water infiltration.
- Remove and replace rotted wood, carpeting, wallboard or other rotted organic building materials.
- Provide for adequate ventilation.
- Clean the area with a solution of bleach and water. (one part bleach to 10 parts water)
- Keep humidity below 50%. Use a humidity gauge to monitor. Air conditioning will remove humidity. If this is not sufficient, use a dehumidifier.
- Use high quality air conditioning filters (MERV 11). This type of filter will capture most airborne mold spores.
- Use a HEPA air purifier. Stand alone and whole house HEPA systems are very effective at reducing mold counts. Mold spores are light and stay in the air for extended periods of time. Properly sized, efficient air purifiers can reduce mold counts by 90%.
What doesn’t work?
- Ionizers. Despite manufacturers claims ionizers are not very effective at reducing mold counts. A MERV 11 air conditioning filter is 2 to 3 times more effective than an ionizer at removing small particles from the air. HEPA air purifiers are 10 to 20 times more effective.
- UV lights. UV light will destroy mold. However, one must have two things — UV light intensity (which decreases rapidly with distance from the bulb) and “dwell time” which is the time that the mold spore is actually exposed to the UV light. The amount of exposure time required to destroy the mold varies greatly for the different types of mold. Some molds are destroyed after a few seconds — others require 8,000 seconds or more. The air traveling in an air duct is moving at a minimum of 100 feet per minute. What are the chances that a mold spore in the duct will be exposed to the UV light for a sufficient length of time? Pretty slim. UV lights have been shown to reduce mold when exposed continuously to the coils of the HVAC system. Cleaning the coils periodically would accomplish the same result.
- Ozone generators. Ozone is a highly reactive, toxic gas. Extensive tests have shown that low levels of ozone will not significantly reduce mold spores in the air. However, adding ozone to indoor air alters the chemical make-up of the air — oftentimes with unexpected and potentially damaging results. Tests have shown that ozone producing machines can actually increase the amount of small particles and potential carcinogens such as formaldehyde. Machines that generate ozone should never be used around people with asthma, COPD or other respiratory diseases.