Category Archives: Indoor Air Quality (IAQ) Testing

VOC (Volatile Organic Compounds) Air Contaminants and Health

Reference list on the plastics, pesticides and other solvent vapors which contribute to poor air quality, allergies, illness, airborne toxicity and carcinogenic risk.

 

NATURAL AND SYNTHETIC CHEMICALS

VOCs – can be classified by boiling points (VVOC, SVOC, VOC and POM) or by chemical structure such as aliphatic / aromatic hydrocarbons or functional R group composition such as oxygenated / halogenated hydrocarbons. Low volatility, high potency organic compounds and those with high polarity can be expected to preferentially take on the form of solid particles rather than remain in a vapor phase. Settled house dust or respirable suspended particles (such as those in the PM2.5 and PM10 size regimes) can also serve as reservoirs for both vapor phase SVOCs and POMs by adsorption. Exposure can be through inhalation, digestion or direct skin contact.

May come from a variety of sources including building materials, pesticides, air fresheners / aerosols, carpeting and linens. (including drapes)

Ozone (O3) ppm

Sulfur Dioxide (SO2) ppm

Nitrogen Dioxide (NO2) 5-35 ppb

Nitric Oxide (NO)

Carbon Monoxide (CO) 0 – 30+ ppm

Carbon Dioxide (CO2) 400 – 1000 + ppm (acts as a respiratory stimulant / increases breathing rate)

Polychlorinated Biphenyls (PCBs) found in electrical equipment

Aldehydes – Because of their solubility in aqueous media and high chemical activity due to the carbonyl functional group, aldehydes tend to be strong mucous membrane irritants affecting both the eyes and upper respiratory tract. This irritation tends to reflexively reduce respiratory rates which will also decrease oxygen intake. Significant examples include acrolein, (major eye / throat irritant in smoke and smog) glutaraldehyde (a biocidal used in medical, dental sterilization as well as duct cleaning and carbon-less copy paper) and acetalaldehyde which is a relatively weak irritant, though it is a proven animal carcinogen and found predominantly in combustion by-products such as cigarette smoke and automobile exhaust gas.

Formaldehyde (HCHO)  0 – 0.5 ppm

Fungicide – Pentachlorophenol, (PCP – used to prevent wood decay)

Pesticides: Organochlorines (chlordane, heptachlor – termiticides, p-dichlorobenzene for moth control)

Pesticides: Organophosphates such as dichlorvos, chlorpyrifos, diazinon, malathion can cause acute neurotoxicity but dichlorvos (used in bug bombs, dog and cat flea collars) has been phased out since 1988 due to potential for animal carcinogenicity except for chlorpyrifos (used for termites, cockroaches and fleas) and diazinon which was phased out in 2000 because of potential exposures to children.

Herbicide 2,4-D risk factor for non-Hodgkin’s lymphoma

Biocides – hypochlorites, glutaraldehyde, alcohols, o-phenylphenol, quaternary ammonium compounds, mercury (Hg) in latex based paint until 1990.

Plasticizers (phthalic acid esters) used to make vinyl more flexible and commonly found in floor coverings. Tends to leech out over time. Some evidence that it contributes to asthma.

Radon (Rn-222) picoCuries / liter

 

PARTICULATE MATTER

Allergens (dust, pollen, dust mites, pet dander)

Bacterial Endotoxins

Fungal Glucans and Mycotoxins from Mold

Total Suspended Particulate (TSP) Matter or Suspended Particulate Matter (SPM) and Respirable Suspended Particles (RSP) measured in particles / cubic foot or micrograms / cubic meter. The size regimes classified by the EPA are Fine particles PM2.5 which are 2.5 microns in diameter or less and Coarse particles PM 10 which are generally 2.5 – 10 microns in diameter.

Asbestos

Heavy Metals – Lead and Mercury in latex paint

 

HEALTH ISSUES

Respiratory / Mucous Membrane Irritation

Asthma

Hypersensitivity Pneumonitis

Humidifier Fever

Legionnaire’s Disease

Pneumonia

Bronchitis

 

SOURCES

Candles & Incense (particularly if burned during pregnancy) can contribute to risks of childhood leukemia. Incense may produce benzo-alpha-pyrene, polycyclic aromatic hydrocarbons (PAHs), and sinapaldehyde. (nasal carcinogen)

Propane fueled forklifts and burnishers (Carbon Monoxide)

Control of Formaldehyde (HCHO) and VOCs in Indoor Air Quality

One of the first issues to address for pre-existing construction is proper selection of materials that have low VOCs and formaldehyde content (UF or Urea-Formaldehyde) and/or that outgas (release the noxious vapors) relatively quickly. Low emission products include:

  • Low VOC paints
  • Low VOC carpeting (though carpets tend to have inherent issues with collecting/releasing dust)
  • Other mastic (waterproofing putty) products that have low levels of 4-phenylcyclohexane (4-PC) which produces a characteristic odor
  • Pressed wood products that have low formaldehyde (HCHO) levels
  • Formaldehyde-free varnishes and lacquers
  • Softwood plywood
  • Oriented-Strand board
  • Decorative gypsum board
  • Hardwood panels
  • Pressed woods with PF (Phenol-Formaldehyde) resin release less HCHO than UF resins

You might want to AVOID:

  • Medium-Density Fiberboard (MDF) sometimes used in cabinets, furniture and doors
  • Hardwood plywood paneling
  • Particleboard
  • Pressed wood products with UF
  • UF-based Acid Cured Finishes
  • Homes insulated with UFFI (Urea-Formaldehyde Foam Insulation) though this is unlikely to be an issue
  • High humidity (keep between 40 – 50 % RH)
  • Occupying the home or property until a proper out gassing period has passed – preferably during hotter weather
Formaldehyde Emissions from variou Construction Materials

Formaldehyde Emissions from various Construction Materials

Then having an outgas period before occupation is good when possible. Preferably during hot, humid weather which tends to accelerate the exit of gaseous residues from the building materials. If you have an existing wood material that is emitting formaldehyde, then the can be treated with scavenging coatings or encapsulated with vinyl materials.

ASHRAE Ventilation Guidelines 2013

ASHRAE Ventilation Guidelines for Acceptable Air Quality – 2013

Another critical factor is having adequate ventilation, particularly during the initial outgas period. Many homes and multifamily dwellings are often built rather “tight” as a response to the desire for energy conservation and reducing moisture intrusion. If it is not a security issue, keeping the windows open even a crack on opposite sides to create a flowing cross-draft can assist out-gassing as well as opening chimney dampeners.

Factors in formaldehyde levels:

  1. Composition of building materials (formaldehyde potency in manufacture)
  2. Loading factor (amount of material in exposed surface area and volume)
  3. Material age
  4. Adequate ventilation taking into account occupancy and room size
  5. Environmental conditions
Indoor Air Exchange Rate Per Hour Table

Indoor Air Exchange Rate Per Hour Table

 

Formaldehyde Levels Indoor Air Quality

How Formaldehyde Levels Decrease Over Time

The use of sorbents (gas absorbent materials) such as activated charcoal can be used to remove relatively high molecular weight VOCs such as toluene, benzene, xylene and methyl chloroform.

For lower molecular weight (MW) materials such as formaldehyde (HCHO), ethylene, and acetaldehyde then potassium permanganate, (KMnO4) activated alumina or specially impregnated charcoal are better choices than regular activated charcoal.

Other special air cleaners may also be used – consult ScanTech for further information.

Indoor Air VOCs: Volatile Organic Compound Contaminants

Volatile organic compounds make up a very large group of chemical substances and are often sub-classified by boiling point temperature ranges which gives an idea of how likely it is to be found in liquid, solid, gaseous forms (or possibly more than one state) at various temperatures. The levels found in breathable air and how they affect air quality are strongly correlated with the boiling points. In general, the lower the boiling point, the higher the concentration that will be present in the air.

VVOC (Very Volatile Organic Compounds)   Boiling points:    less than 0 C to 100 C

VOC (Volatile Organic Compounds)  Boiling points:   50 C  – 260 C

SVOC (Semi-Volatile Organic Compounds)   Boiling points   260 C – 380 C                                        (includes many biocides)

POM (Particulate Organic Matter aka Solid Organic Compounds)  Boiling points exceeding 380C includes PAHs (polycyclic aromatic hydrocarbon compounds)

Carbon Monoxide Safety Levels and Indoor Air Quality

An important component of indoor air quality testing is measurement of abnormal levels of carbon monoxide.

Carbon monoxide (CO) is a result from all forms of combustible sources, from smoking and wood fires to propane and fuel-powered automobiles. Poisoning of a human subject comes in two forms – short term exposure to high levels which can cause severe illness or death, or longer term exposures at lower levels which may cause chronic symptomatology.

While actual death is relatively rare, there are far more cases that occur with sub-lethal exposures over a broad range of concentrations. (30 – 100 ppm by volume or ppmv) At the lower end (40 – 60 ppmv) headache and low levels of fatigue, and at higher levels (75 – 200 ppmv) nausea, vomiting and especially sleepiness.

Symptoms with Different Blood COHb Levels

Symptoms with Different Blood COHb Levels

Carbon monoxide and oxygen both bond to hemoglobin in the blood and will compete with each other over binding sites, but CO has the advantage as it binding sites have an affinity or preference of binding with CO that is 200 times greater than O2. (atmospheric oxygen) The result is decreased oxygen carrying capacity in the blood with the consequent neurological symptoms of oxygen deprivation as listed above as well as reduced oxygen to other body tissues. It also binds to intracellular proteins such as tryptophan oxidase, cytochrome oxidase,  myoglobin, and dopamine hydroxylase which may cause extra-vascular effects.

The result of CO combining with hemoglobin is to form carboxyhemoglobin. (COHb) Exposure to CO can be evaluated by measurement of the levels of COHb in the blood which is typically less than 1% for unexposed individuals. This is the % amount of blood hemoglobin bound with carbon monoxide. Cigarette smokers typically have a level of 3% – 8%. OSHA has a permissible exposure limit (PEL) of 50 ppmv over an 8 hour time-weighted average (TWA) in which case an individual would have a COHb level of approximately 5%. At 100 ppmv, it would be over 10%.

COHb Levels Resulting from Exposure Duration

COHb Levels Resulting from Exposure Duration

Even low level carbon monoxide exposures can cause issues in compromised human subjects such as those with cardiovascular disease. The lowest level at which COHb can show as a physiological symptom is 3 %- 4 % COHb. At 6 % COHb, arrhythmia may be induced in exercising patients with coronary artery disease with a risk of sudden death. There is also evidence that suggests that carbon monoxide exposure may contribute to atherosclerosis.

Studies have shown that those with flu-like or neurological symptoms had COHb levels of 10% or greater. (24% and 3 % respectively. Sub-acute carbon monoxide poisoning commonly goes unrecognized and is not diagnosed because it mimics other conditions and is present at the residence / workplace – not the doctor’s office.

Those at higher risk include pregnant women, young children, the elderly, individuals with conditions that already compromise O2 availability, and those that use certain medications and drugs.

For a discussion of CARBON DIOXIDE poisoning which is an entirely different phenomena, see the post here:

New Homes and Carbon Dioxide Levels: The Overlooked Indoor Air Quality Health Hazard

If you live in the Dallas / Fort Worth, Houston or Austin metropolitan areas and suspect carbon monoxide / dioxide poisoning or other indoor air quality issues, then contact ScanTech Technical Consulting for an evaluation.