One of our school portables has a Cladosporium level that is higher than  the outside level.  I was told that is related to housekeeping. Is that correct?  I also took a tape lift sample from the same portable and it showed major level of Ascosporium.  Would a general cleaning with bleach take care of this problem or do we have to do anything else.  My other question is about the air-conditioning and the HVAC system.  Is there a guidebook or training that would cover indoor air problems and their association with the HVAC (heating, ventilating and air-conditioning)  system and how it can be corrected? Anon, California 

If you have indoor Cladosporium levels which are clearly higher indoors (as compared to outdoor levels), this indicates there is one or more areas indoors that are infested with Cladosporium. 

Cladosporium is one of the most ubiquitous mold genera; growing equally well on substrates both outdoors and inside buildings.  It is the most common black mold.  Sensitive individuals exposed to elevated airborne concentrations can develop symptoms of chronic allergy or even asthma. 

The presence of Cladosporium in indoor spaces may be due to the intrusion of mold particles from open windows/doors and subsequent deposition on horizontal building surfaces.  It may also be due to inadequate maintenance in the sense that water leaks (which damage ceiling tiles and other building materials) are major causes of localized mold infestations that on spore dispersal may cause significant airborne exposures in the surrounding area.  Such leaks and damaged materials should be remediated quickly.  If not, significant levels of airborne mold would occur.  It is not due to the inadequacy of cleaning but inadequate maintenance. 

The mold described as Ascosporium is not familiar to me.  However, significant mold concentrations observed in sticky tape samples indicate that the surface is mold infested. 

Mold infestations can be abated by several different means.  If the infestation is significant and the material appears not to be worth salvaging, it is better to remove and replace it.   This is the case for materials such as ceiling tiles and other paper-containing products.  For hard surfaces such as wood, the infested surface should be first scrubbed with a hard brush using diluted bleach (cup: a gallon of water) and then subsequently repainted. 

There are several guidebooks available that can be used by both professionals and others to evaluate air quality problems associated with heating, cooling and air-conditioning systems.  These include USEPA's Building Air Quality Manual(http://www.epa.gov/iaq/largebldgs/baqtoc.html) and Tools for Schools (http://www.epa.gov/iaq/schools/pubs.html#IAQ%20Tools%20for%20Schools%20Kit) strongly  recommend that you obtain a copy of the latter either through the above links or through USEPA  Region 9 in San Francisco.  They will be more than happy to send you a copy.