Preventing & Solving Mold Problems in Schools

Preventing & Solving Mold Problems in Schools Rich Prill Building Science & IAQ Specialist Washington State University Extension Energy Program Spok...
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Preventing & Solving Mold Problems in Schools

Rich Prill Building Science & IAQ Specialist Washington State University Extension Energy Program Spokane, WA 25 years IAQ Experience Region 10 EPA IAQ Education & Technical Resource > 500 NW School Walk-Throughs Building Operator Certification IAQ Instructor

Indoor Dampness, Molds, and Health

Dry

Surveys find dampness and molds are common in schools and office buildings Causes: – water leakage through roofs and walls – plumbing system leaks – groundwater floods – damp construction materials – high indoor rates of moisture generation – entry of humid outdoor air – water vapor condensation on cold surfaces of windows and walls Based on the available surveys, approximately half of U.S. homes have visible evidence of a dampness problem or mold contamination

Molds & Bacteria

Dry

• Can lead to microscopic airborne particles, containing allergens or chemicals with potential to induce inflammation in the respiratory system • Dampness also increases emission rates of gaseous non-microbial chemicals such as formaldehyde

• High indoor relative humidity can increase house dust mites - - a very important source of indoor allergens

Molds Mold concentrations generally higher outdoors Primarily allergic reactions –Eye, nose, throat irritation –Shortness breath –Dizziness, fever, lethargy –Digestive problems –Skin rash

National Academy of Science Institute of Medicine (2004)

Dry

Extensive study concluded that building dampness and mold represented a public health problem “ Building dampness and mold were associated with 30% to 50% increases in a variety of respiratory and asthma-related health outcomes “ “Steps should be taken to reduce building dampness and mold, including various education efforts, reviews of buildings codes and contracts, and an exploration of financial incentives for reduced dampness.”

Molds & Dampness

Dry

Of the 21.8 million people reported to have asthma in the U.S., approximately 4.6 million cases (~20%) were estimated to be attributable to dampness and mold exposure in the home

The associated annual cost of current asthma attributable to dampness and mold in the U.S was estimated to be $3.5 billion

Mold Exposure and Reaction • Exposure is complex = depends: – Species compete: come and go – Metabolic products produced by each species – Amount of exposure – Duration of exposure – Individual susceptibility

Due to Uncertainties: Practice “Prudent Avoidance” • People should not live in the presence of mold, moldy odors, damp conditions • Dampness, odors and visible mold should “corrected” as soon as possible Damp environments have been shown to be directly related to adverse health effects

Why Mold Problems ?

Mold Growth  Spores

 Nutrients  Temperature o

o

(40 F to 100 F)

 Moisture

Mold Just add water …

Some climates are prone to mold problems

Moisture Rules • Moisture flow is from warm to cold

• Moisture moves from more to less • Air transports moisture from

• high pressure to low pressure areas • Gravity pulls water down • Water wicks up • Drainage is critical

Just Add Water From the Outside From the Inside

Water entry from Outside • • • • • •

Roofs and Walls Windows, Doors, Flashings Crawlspaces, Basements, Slabs Where materials meet Plumbing systems Heating/Cooling systems – Leaky ducts Condensate

Patios and decks lower than floors and slope away from building Garage floor lower than main floor and slope away from building Driveway lower than garage door and slope away from building Grade lower than main floor and slope away from building

Building Science Fundamentals • Nature is lazy (path of least resistance) But, molds are NOT lazy!

• The path of least resistance is the path to problems, unless you know your way • It costs about 3 times more to fix it later • Gravity is free: slope to drain flashing are your friends

Avoid Flat Roofs

Gravity always trumps caulking

Another good argument against flat roofs

Mark on floor plan to ensure thorough check from the inside Potential Water Entry Areas

Avoid built-in cabinets at windows

Window leak behind built-in cabinets = mold

Drainage plane ? Flashing ? Weather Resistant Barrier ? Drying potential ?

Diameter (inches)

Capillary Rise (inches)

capillary break

capillary breaks

E.I.F.S.

E.I.F.S.

Block = Rigid Sponge

irrigation system defeating roof over-hang

Ensure proper drainage

the “Best” water leak:

Small enough to not cause problems

Large enough to be noticed

If it gets wet, it must dry quickly 24 – 48 hours is recommended Use your judgment !

If water gets in . . . it must dry out quickly

If can’t stop the water, remove the mold food

temporary solutions

Preventing Biological Growth

Thoroughly dry wet materials within 48 hours

Drying Add heat (vaporize)

+ Aggressive Air Exchange (remove) (outside air)

Note: De-Humidification may be necessary

1 school out of 44 2008-2009

Dehumidifiers Installed

Ensure proper drainage

Warm Air Rises

00

70 F

70 0 F

40

0

F

Portable is damp & smells moldy

“unplanned air flows”

What goes out

Must come in

Open crawl vents often allow more air (+ contaminants) to enter buildings Also: cold floor, frozen pipes, pests

Closed crawl vents can result in build-up of radon, moisture, etc.

Can’t decide ?

Crawlspace Guidance

Exhaust air from under groundcover to prevent entry of radon or other contaminants

Moisture

Fundamentals

Relative Humidity The degree of saturation of the air % of water holding capacity

“Relative” to the temperature If the air is half full = 50% rh If the air is 90% full = 90% rh Most molds will grown at ~85% rh and above

RELATIVE HUMIDITY FACT: Warm Air Can Hold More Moisture Than Cold Air TEMP. R.H.

RELATIVE HUMIDITY Raise the air temperature = lower the relative humidity TEMP.

R.H.

RELATIVE HUMIDITY Lower the temperature = increases the relative humidity TEMP.

R.H.

Moisture Dynamics Lower the temperature enough and the air becomes completely saturated

= Condensation

Moisture Dynamics Temperature at which air becomes completely saturated =

Dew Point Temperature =

100% Relative Humidity

40

0F

100% rh (fog)

40

0F

100% rh (fog)

70

0F = % rh

40 0F 100% rh (fog)

70

0F

=

35 % rh

COLD OUTSIDE

DEW POINT

High Relative Humidity = Mold

COLD OUTSIDE

Areas of High RH

RH% and Dew Point 95 % RH = the dew point is: only 3 degrees below air temp

85 % RH = the dew point is: only 6 degrees below air temp

60 % RH = the dew point is: • 20 degrees below air temp 0

70 F building air temperature

allow air circulation

Vent moisture outside

Mold under sink

Infrared Camera

Energy - Moisture Unplanned Air Flows

Warm

Cold

Optimum Moisture Level ? Depends on Occupants – Sensitivity to “dryness” – Sensitivity to “dampness”

Depends on the Building – Masonry & Plaster – Sheetrock & Wallpaper – Temperature of Materials

Suggest 30% to 50 % for IAQ

Relative Humidity in NW Schools • Properly ventilated schools generally result in lower relative humidity levels compared to many homes • Occupants in schools can experience “drying” effects from these lower relative humidity levels compared to their homes

Dust Mites dine on skin flakes

Mite feces = potent allergen

Require about 45% relative humidity to survive

Is there mold ? • Visual inspection – Indication of water or moisture – Visible mold or “mildew”

• Moldy - Musty odors • Health symptoms suggest exposure

Thorough Investigation Careful examination inside and out: faulty exhaust water leaks inadequate ventilation capillary action combustion cold spots duct leaks activities A thorough investigation also identifies the boundaries & extent of the cleaning & drying necessary for remediation work

Find the water leaks

water leaks = potential molds

Potential Water Entry Areas

Unsealed ducts + wet crawl space = moisture in building

Indoor temperature & relative humidity logger

100% 80% 60% 50% 40% 30% Date and Time

surface temperature

Infrared Camera

energy - moisture - unplanned airflows

calcium chloride vapor emission test: quantify the volume of water vapor radiating from a concrete slab Use this test to model the amount of moisture that emits from 1,000 square feet of slab surface in 24 hours.

result is expressed as "pounds" which is the equivalent weight of water, emitted as vapor, over 1,000 square feet in 24 hours. This test requires the use of a gram-weight scale with a gradation of 1/10th (0.1) gram. The calcium chloride container is weighed before and after exposure to the concrete slab. Vaprecision.com

Evidence of moisture and/or mold may not be obvious

“Blank” switch plate covering inspection hole

leaky windows + built in cabinets

Contain work areas with closed doors or poly sheeting Check pressures between zones Contain debris – do not track through clean zones Turn off air handlers and protect ducts

remove at least 2 feet of material around visible growth

CLEANING: Scrub!

Whoa ! Time to get serious with containment and PPE

note air pressure Maintain a negative pressure zone

Do It Yourself or Contract? • Depends on size of problem • Discuss with occupants • Consider your abilities • Look at cost-benefit

EPA Guidance for Mold Remediation in Schools IICRC S-520 Standard and Reference Guide for Professional Mold Remediation Institute of Inspection, Cleaning & Restoration Certification

Testing for Molds

Currently no meaningful mold exposure standards or thresholds Too many uncertainties: thousands of mold species measurements health impacts occupant sensitivities exposure complexities

Testing for Mold EPA and New York City guidelines

do not recommend airborne mold sampling as part of an investigation or remediation effort But, useful information may be obtained

IAQ Testing “Absence of Evidence . . .

is not Evidence of Absence” Testing can produce “False Negatives” But not “False Positives”

Air Sampling for Molds Compare outside to inside Compare “non-problem” zone with “problem” zone Look for viable and non-viable Look for other pollutants

Airborne sampling is a “snapshot in time” Settled particle sample is a “time integrated test” and provides evidence of other pollutants!

Who is doing the inspection, sampling, and analysis? Interpretation is critical aspect !

Air samples are a “snap shot in time”

Cleaning Mold: Is Bleach Necessary?

Bleach Bleach can kill - does not clean – Not always necessary to kill mold, But must remove mold – Soapy water is less dangerous – If necessary, treat cleaned surfaces with dilute bleach

Replace or Salvage? • Soft, absorbent materials that get moldy should usually be discarded – Paper, textiles, wallboard – “freeze-dry” valuable papers

• Small amounts of obviously superficial contamination may be cleaned with soap and water.

Preventing Mold • • • • • •

Water-resistant buildings Proper drainage Immediate & thorough drying Monitor for leaks & “cold areas” Exhaust “point sources” Ventilate properly