Solid Science Practical Solutions


Hot & Humid Summer Weather Leads to Mold

Mold can lurk in building systems over the summer.  Warm temperatures, high humidity, and little ventilation all contribute to the growth and spread of mold. 


The result of an issue can range from concerned residents and delayed building openings to a full-blown remediation project or serious illness.  But there are preventative measures you can take.  This mold Q & A will answer many of your questions:


Q - Mold has been around forever – Why is it such an important issue lately?


A - In recent years the weather extremes in our area seem to be increasing in frequency, intensity and duration.  Long periods of wet and humid conditions can overwhelm aging air conditioning systems.  In many schools and other buildings, areas are not air conditioned at all.


Many older buildings were constructed of masonry and hardwoods with minimal insulation.  Such buildings were less susceptible to mold since the materials were harder for molds to grow on and as air and moisture moved in and out, building materials tended to dry faster.  Newer buildings are more energy efficient, which also serves to trap in moisture (and indoor air contaminants) and reduce fresh air exchange, leading to higher risk for microbial growth.


Medical science has also learned a lot about the health effects of molds in recent years, although there is still much research to be done. 


Q - What exactly is mold?


A - Molds are living organisms in the Kingdom Fungi.  They mostly come from the outdoors from trees and other vegetation, but mold is found almost everywhere.  Molds grow best in warm, damp, and humid conditions, and spread and reproduce by producing spores which are microscopic, tough and can float in the air for long periods of time.  This fact is especially important in buildings with forced air ducted systems which can help spread mold spores throughout the building.  No one knows how many species of mold exist but it is estimated that there are “hundreds of thousands”.  Mold can grow on virtually any organic substance, which means most common building materials, including wood, paper, wallboard (sheetrock), cardboard, ceiling tiles, insulation, clothing, leather goods, upholstered furniture, carpets/rugs and foods.


Q – Can mold really make you sick? 


A - The best documented health effects are upper respiratory and “hay fever-like” symptoms such as cough, sneezing, headaches, tightness in the chest, scratchy throat, difficulty breathing, red and itchy eyes, etc.  Science has also shown that mold exposure can cause asthma or make it worse in some people.  Other medical studies suggest a link between mold exposure and lower respiratory issues such as bronchitis and emphysema.  Despite media reports, we do not yet have proven medical evidence that environmental mold exposure causes other conditions such cancer, heart or skin diseases; studies are ongoing.


The duration of symptoms varies depending on the individual’s health status.  In some cases, the health effects and mold sensitivities that may develop can be long lasting or life-long.


Q – Is all black mold toxic and dangerous?  I’ve heard a lot about “toxic mold” and “black deadly mold” over the last few years - How concerned should I be?


A - Those alarming terms show up in the media on a regular basis.  Some mold-related companies use them as “scare tactics” to frighten building managers and owners into action.  Such terms are not based on good science and are not useful in understanding the risks of mold exposure and making good decisions.


Your concern should be based on such factors as:

  • Extent and location of the mold growth
  • The source(s) of moisture
  • Types of building materials impacted
  • Medical status of occupants
  • Occupancy patterns and activities
  • Type and effectiveness of heating and cooling systems
  • The ambient environment


In general, the longer people are exposed to mold and the higher the levels of exposure, the greater the risk of negative health effects.  The actual risks are difficult to determine and depend on the above factors and each individual’s immune response to the exposure.  That is one of the key reasons that there are no government regulations or authoritative exposure limits for mold. 


These groups of people have Increased risk of negative health effects from mold exposure:

  • People with known mold or other outdoor allergies
  • People with compromised immune systems
  • People with chronic (especially respiratory system related) diseases
  • The elderly and very young
  • Those occupying chronically “damp” buildings


However, some healthy people can also develop sensitivity to mold and get sick from mold exposure.


Q - What should I do if I suspect mold in my BUILDING?


A - Since mold control largely depends on moisture control, here are several helpful tips:


  • Don’t panic!  Not all wet building materials become moldy, not all discolored building materials have mold and not all mold conditions are serious. 
  • Don’t ignore possible signs of water leaks or mold.  Immediately look for possible sources of moisture without disturbing suspected mold (disturbance can spread microscopic mold spores into the air and around the building).  
  • Repair sources of water as soon as possible and dry the area quickly with dehumidifiers and/or fans.
  • Temporarily protect/seal the suspected moldy area by taping heavy gauge plastic over the area, being careful to leave a safe margin of at least 1 foot around the discolored area.
  • Small areas (<10 sq. ft.) of visible mold on wallboard or other materials can usually be removed by a maintenance person or general contractor using basic precautions.
  • If you find or suspect more than 10 sq. ft. of mold or smell “musty” or “earthy” odors but don’t see any water damage or leaks, consider the services of a professional Industrial Hygienist or Indoor Environmental Consultant.  Such qualified professionals can evaluate the problem, test as needed and provide objective guidance on safely remediating the mold. 


CAUTION: To avoid a conflict of interest and potential rip-offs, the best source of objective advice is from a qualified consultant who is not also a mold contractor.


Q – What can I do to prevent mold in MY BUILDINGS?


A – It’s all about moisture control!  That can range from preventing or quickly repairing roof, foundation, window, or plumbing leaks to control the relative humidity in your buildings.


Recommendations for the control of relative humidity:


  • Have all air conditioning units serviced and cleaned in the early summer including, changing filters, checking all mechanical components, cleaning air handlers, pans and coils, etc.
  • Immediately respond to water stained ceiling tiles.  Remove tiles to determine the source.  In high humidity, condensing pipes are common resulting in water dripping onto ceiling tiles.  In that case consider:
      • Install additional non-absorbent insulation on pipes
      • Seal any gaps between the ceiling plenum and the exterior of the building
      • Leave ceiling tiles off in dripping areas during high humidity.  This will also help reduce the temperature differential between the room and ceiling plenum.
      • Be sure the actual pipes are not leaking
  • Reduce the percentage of outside air intake to the lowest possible level.  Some systems can function well with 0% outside air intake which is preferable in high humidity conditions.
  • Run air conditioning as many hours as possible including over weekends.
  • If relative humidity is regularly near or above 70% inside the building despite the steps above, consider running the heat for a few days periodically to reduce the humidity levels.
  • Temporarily install commercial grade dehumidifiers with drain kits (to avoid having to empty water bins).  Keep the doors closed to rooms with dehumidifiers to improve effectiveness.
  • Reduce the amount of susceptible materials such as rugs and carpets, upholstered furniture, absorbent particle board furnishings, cardboard boxes, plush toys, and excessive paper goods, etc.
  • Store smaller susceptible materials in sealable plastic bins.
  • Prevent water from pooling along foundations, especially in buildings with occupied basement rooms.  Diversion of leaders and proper grading are key approaches.  Of course, immediate repair of cracks or other openings in foundations that can allow water to penetrate, is critical.


Despite the best preventive efforts, water intrusion, high humidity and mold growth can happen.  How you respond can make the difference between a small event and a major case involving health problems, expensive repairs or reconstruction, regulatory enforcement and possible litigation.


GSE has many years of experience in water intrusion, mold and other indoor our quality issues.  Our team of experts is available to provide professional advice and assistance throughout NJ.  Our practical experience and academic training allows us to give you state-of-the-art technical guidance that is balanced with real-life practical considerations.


Call for a free phone consultation and more information.