Gas testing pump (C) Daniel Friedman Formaldehyde Gas HCHO Exposure Limits
Formaldehyde Gas (Formalin Gas) Exposure Standards & Limits in Buildings

  • FORMALDEHYDE GAS EXPOSURE LIMITS - CONTENTS: Indoor air quality testing for harmful levels of formaldehyde outgassing or gas. Formaldehyde gas test methods; Formaldehyde gas exposure limits, Level of toxicity of formaldehyde gases. What levels of formaldehyde gas are acceptable. Formaldehyde exposure and/or testing standards are presented for Australia, Canada, the E.U., the U.S., the E.U., New Zealand.
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Formaldehyde Gas Exposure Limits in Buildings:

What are the allowable exposure limits & standards for formaldehyde gas? What levels of formaldehyde gas are acceptable. Formaldehyde exposure and/or testing standards are presented for Australia, Canada, the E.U., the U.S., the E.U., New Zealand

Page top photo, the author's GasTech™ pump using a colorimetric gas detection tube in a private home.

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Formaldehyde Gas HCHO Characteristics, Toxicity, Gas Exposure Limits

Formaldehyde is an organic chemical with formula HCHO, CAS No. 50-00-0 that is very widely used in industry as well as in a plethora of consumer products from cosmetics and clothing to furnishings and construction materials as well as in disinfectants and preservatives. Formaldehyde is an intermediate chemical used in the production of resins (e.g. glues in fiberboard and OSB, and in wrinkle-resistant clothing), industrial chemicals, preservatives (including in some cosmetics and skin creams), and in shampoos and glues. Formaldehyde may also be present in food or may be generated by smoking indoors.

In the U.S. formaldehyde is detected in outdoor (ambient) air in urban areas at levels between 11 and 20 parts per billion (ppb) while indoors formaldehyde levels are commonly reported between 0.10 and 3.68 parts per million (ppm). - US EPA (2000)

There are currently no national standards in place for formaldehyde in composite wood products. However, EPA is in the process of finalizing rules that will set limits on formaldehyde emissions from composite wood products such as hardwood plywood, medium-density fiberboard, and particle board that are sold, supplied, offered for sale, manufactured, or imported in the United States. - U.S. EPA cited below

Article Contents

Human Response to Various Levels of Formaldehyde Concentration in Building Air

Formaldehyde: (or Formalin in some literature) gas exposure limits - As an additional example using Formaldehyde, in a screen we may test for very low levels in a building (.05 ppm), but the range of human response (also widely variable individually) may be summed as follows:


Health Effects of Exposure to Formaldehyde1

Formaldehyde Level in Air Expected Health Effects Comments
> .01 ppm   mild irritation or allergic sensitization in some people [>0.0123 mg/M3]
> 0.5 ppm   irritation to eyes & mucous membranes [>0.615 mg/M3]
> 1.0 ppm  possible nasopharyngeal cancer [>1.23 mg/M3]
3.0 ppm respiratory impairment and damage [ 3.684 mg/M3 ]
Approx. 0.0001 mg/m3 Cancer risk level of 1 in 1-million

Amoore (1983)

[0.0008 ppm]

0.004 mg/m3 ATSDR chronic MRL

ATSDR (1997)

[0.32572 ppm]

203 mg/m3 LC-50: Lethal concentration for rats

US DEHS (1993)

[165.3 ppm]

400 mg/m3 LC-50: Lethal concentration for mice

US DEHS (1993)

[325.72 ppm]


1. The values in this table are commonly-cited health effects of exposure to formaldehyde in air, not the legislated / recommended exposure limits nor exposure recommendations for formaldehyde. Formaldehyde exposure limits or recommendations are given below.

2. Watch out: mg/m3 (micrograms per cubic meter) cannot be equated to ppm (parts per million) or ppb (parts per million or parts per billion) concentrations of a substance in air. Conversion between these measurement scales depends on the molecular weight of the substance as well as on the temperature and pressure in the environment being measured.

3. Details about converting concentrations of formaldehyde between mg/m3 and ppm and example calculations converting levels of formaldehyde between ppm and mg/m3 are found at CONVERT PPM - mg/m3 Bracketed numbers in the table above are calculated as shown at CONVERT PPM - mg/m3 assuming conditions of sea level pressure (1 ATM) and assuming a temperature of 25°C.

See FORMALDEHYDE HAZARDS for a table of "Common Concentrations of Formaldehyde (HCHO) in Indoor & Outdoor Air " - formaldehyde levels found outdoors and in buildings and a comparison of those levels with current residential exposure standards for formaldehyde.

Formaldehyde MSDS sheets: This FORMALDEHYDE MSDS [PDF] from Mallinckrodt Chemicals notes that typical composition of formaldehyde in industrial use is comprised of 37% formaldehyde, 10-15% methyl alcohol, and the remainder water. Synonyms for formaldehyde exposure are Formaldehyde 37%, Formalin, Morbicid Acid, Methylene Oxide, Methyl aldehyde, all bearing the CAS No.: 50-00-0 and expressed by the chemical formula HCHO and CH3OH in water.

Common industrial or workplace formaldehyde gas exposure limits or Recommendations

Formaldehyde is normally present at low levels in buildings, usually below 0.03 ppm both indoors and outdoors. However, buildings with high levels of pressed wood products can have higher indoor levels. For example, many manufactured homes have levels well above 0.03 ppm, due to their relatively small volume and large surface area of formaldehyde emitting materials.

U.S. Indoor Formaldehyde Exposure Limits, Recommendations, Regulatory Advisory Numbers

There are generally two different categories of exposure limits for formaldehyde (and other chemicals or contaminants in the workplace):

  1. Short-time exposure levels are used for preventing acute health effects of formaldehyde on individuals
  2. Long-term exposure levels are used for preventing the chronic health effects of formaldehyde. "Long term" exposure values are typically given as time weighted average (TWA) values for 8 or 24-hour time periods and are intended to protect people in the indoor environment from exposure to formaldehyde over a lifetime. (Salthammer et als., 2010).

Definitions of Common Exposure Limit Acronyms: EPERG, STEL, LC50, IDLH, REL, STEL, PEL

The following list of definitions of common exposure limit recommendations is excerpted from US EPA: Formaldehyde Hazard Summary. Notice that these are generally industrial or workplace environment measures.

Formaldehyde HCHO Limits / Recommendations in the European Union E.U.

In the E.U. formaldehyde use in household products and chemical outgassing from wood products has been more closely regulated since 2003 (Germany) or 2006 (elsewhere), and as The Times pointed out, in Japan it is home builders who are required to limit the overall formaldehyde levels in new construction. - op. cit. 3/11

Formaldehyde release from products is regulated in the E.U. for panel products such as un-faced cement-bonded particleboards, wet-processed un-faced fibreboard (when no formaldehyde emitting resin was added to the process) and for un-faced, coated or overlaid wood based panels (which might include laminate flooring) when glued with resins that emit either no formaldehyde or only negligible amounts of formaldehyde after production. The authors (Schwab et als) cite the use of isocyanate or phenolic glues as examples.

There are two formaldehyde outgassing level certification indicators used on products in the E.U.

  1. Germany, through the German Association of Producers of Fabricated Houses (BDF), specifies 0.03 ppm panel boards asserted as equivalent to Japan's formaldehyde emission class F
  2. "Blue Angel" labels indicate that the board has a formaldehyde outgas rate of 0.05 ppm (with changes or diminution over what lifetime is not stated)

In Europe there is one reference method and there are three or four derived methods for testing the level of formaldehyde in a building or in a material:

Reference Formaldehyde Testing Method: The E.U. Formaldehyde Testing Chamber method EN 717-1 with three different volume options.

The chamber method used in the E.U. involves a large-enough chamber that it can contain multiple structures of cabinetry or shelving or sheet goods. This method is illustrated and discussed by Schwab et als. (un-dated). Tested components are sealed in the test chamber for up to 28 days, permitting formaldehyde emission level measurements in ppm or mg/m3.

Derived Formaldehyde Testing Methods in the E.U.:

Formaldehyde Emission Limits for the E.U. were published by Schwab et als (cited below) and vary depending on the testing method used. The authors we cite provide a helpful chart from which we excerpt and adapt below. Please see the original for complete details.

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EU Formaldehyde limits on types of panels & boards

Australia & New Zealand Formaldehyde HCHO Emission Standards, Limits & Regulations

Australian Standards, labelling and product certification, are available at Engineered Wood Products Association of Australasia website at:

Australian, E.U. & U.S. Formaldehyde Emission Standards & Testing References:

Canadian Formaldehyde Exposure Standards

"The risk of developing cancer from formaldehyde levels found in Canadian homes ... is essentially zero" - Health Canada

Table of Formaldehyde Exposure Recommendations, World Wide

The following table is excerpted from Salthammer, Tunga, Sibel Mentese, and Rainer Marutzky. "Formaldehyde in the indoor environment." Chemical Reviews 110, no. 4 (2010): 2536-2572. More work by these authors is cited at REFERENCES.

[Click to enlarge any image]

In comparing the recommended exposure limits for formaldehyde in various countries around the world as given in the table below note that the conversions from ppm are given in micrograms: ug per m-3 NOT milligrams: mg/m3 (micrograms per cc rather than milligrams per cubic meter).

Table of formaldehyde exposure recommendations from around the world - Salthammer et als (2010) cited in this article

Calculate Conversions Between PPM and mg/m3

How & When to Convert Exposure Limits in ppm to mg/m3 for Formaldehyde or other Substances

Concentrations of chemicals in air are typically measured in units of the mass of chemical (milligrams, micrograms, nanograms, or picograms) per volume of air (cubic meter or cubic feet). However, concentrations may also be expressed as parts per million (ppm) or parts per billion (ppb) by using a conversion factor. The conversion factor is based on the molecular weight of the chemical and is different for each chemical. Also, atmospheric temperature and pressure affect the calculation. - Boguski (2006)

Only concentrations of substances that exist as a gas or vapor in air at "normal" room temperatures and pressures can be expressed as parts per million. In order to be able to express exposure limits in a consistent manner across a variety of materials, including metals, salts or other substances that are not airborne as vapors, occupational exposure limits are typically given as milligrams per cubic meter of air or mg/m3 of a substance in air. Still other substances such as airborne asbestos or fiberglass fibers may be expressed as fibers / cc but we warn that "fibers" needs to be more carefully defined since the size of particles of these materials can vary significantly and as health implications may also vary by particle size.

The Canadian Centre for Occupational Health and Safety (CCOHS) ( and the ACGIH ("Threshold Limit Values TLVs™) discuss both threshold limit values (TLVs™) and Biological Exposure Indices (BEIs™) and give formulas for TLVs in both ppm and in mg/m3 assuming that these measurements are made at 25C and 1 atmosphere of pressure (1 ATM = 760 torr = 760 mm Hg = 406.64355 inches of water).

One Gram Molecular Weight or GMW or "mole" can be defined as the quantity of a substance whose weight in grams is equal to the molecular weight of that substance

Moles or molecular weights of any substance are calculated as

Atomic Weight of a Substance (from the periodic chart of its comprising elements expressed in atomic mass units) x number of atoms of each element present = the formula weight of the substance. So any GMW or mole calculations for any substance require that you know the atomic weight of its individual comprising atoms as well as the number of atoms making up substance. The atomic weights of elements are found in a periodic table or in tables maintained by NIST.

Formulas for Converting Concentration of a Substance Between ppm and mg/M3

Assuming a pressure of 1 ATM and a temperature of 25C, we can write equations to convert between concentrations of a substance in parts per million (ppm) to concentration of the same substance in mg/M3 as follows: - Boguski (2006)

To convert ppm to mg/m3

Concentration of X (mg/m3) = 0.0409 x concentration of X (ppm) x molecular weight of X

To convert mg/m3 to ppm

Concentration (ppm) = 24.45 x concentration (mg/m3) ÷ molecular weight of X

Formaldehyde's atomic weight is 30.02598

To avoid confusion between milligrams per cubic meter and micrograms per cubic meter: 1.0 mg/m3 = 1000.0 ug/m3

Examples of Formaldehyde Concentration Conversions between ppm and mg/M3 at 1 ATM and 25°C

Formaldehyde Level in ppm Formaldehyde Level in mg/m3 Notes
3 ppm 3.684 mg/M3  
1 ppm 1.23 mg/M3  
0.5 ppm 0.6 mg/M3  
0.1 ppm 0.123 mg/M3 Checkpoint with table 5 from Salthammer quoting Chemical Reviews and given above
0.01 ppm 0.0123 mg/M3  
325.72 ppm 400 mg/M3

ppm calculated per Example 2 in Notes below,

or 303 ppm using Lenntech's calculator
at converter-parts-per-million.htm

165.3 ppm 203 mg/M3  


Use these formulas to convert between ppm and mg/m3 assuming that the measurement is made at 1 ATM and 25°C (These numbers will be incorrect at other temperatures or pressures. )

0.0409 x concentration of Formaldehyde (in ppm) x molecular weight of Formaldehyde = Concentration of Formaldehyde in (mg/m3)

Example#1: convert 3 ppm of formaldehyde to mg/m3

0.0409 x 3ppm HCHO x 30.02598-HCHO = 3.68418775 mg/m3

Using the molecular weight of formaldehyde = 30.02598

Example #2: convert 400 mg/m3 of formaldehyde to ppm

24.45 x concentration 400 (mg/m3) ÷ 30.02598 molecular weight of Formaldehyde = 325.7179283 Concentration (ppm)

If you are working in micrograms per cubic meter (ug/m3) instead of milligrams per cubic meter (mg/m3) you can use these same equations to obtain parts per billion (ppb) instead of parts per million (ppm).

If you are working in concentrations of chemical substances in water the usual measurements are in mg/L or ug/L.

Just to keep our decimal places straight, if you are converting between ppm and ppb, 1 ppm = 1,000 ppb. A milligram is 1/1000 of a gram or 0.001 grams; a nanogram is 1/1,000,000,000 grams or a billionth of a gram, or 0.000000001 grams.

Definition & Composition of the molecular mass (popularly "weight") of Formaldehyde

The molecular mass of any substance is the sum of the mass of its constituent atoms. To have a useful meaning, all atomic mass units are expressed relative to the isotope 12C which is defined to have a mass of 12. Formaldehyde has an atomic weight expressed in atomic mass units or molar mass of 30.02598 computed as follows:

What is the atomic mass of Formaldehyde?

A molecule of formaldehyde is made up of a combination of atomic elements written as CH2O (or HCHO)

Atomic mass of H, Hydrogen = 1.00794

Atomic mass of C, Carbon = 12.0107

Atomic mass of O, Oxygen = 15.9994

These atomic mass units or popularly, "atomic weights"are given in the atomic table. Adding these for CH2O = (H + H + C + O) = (1.00794+1.00794+12.0107+15.9994) = 30.02598

What is one gram molecular weight of Formaldehyde? What is one mole of Formaldehyde?

One gram Molecular Weight (GMW) of any substance is defined as the amount of the substance whose weight in grams is numerically identical to the molecular weight of that substance.

One gram molecular weight (1 GMW) of formaldehyde = 30.02598 grams.

How many grams of formaldehyde are in one mole of that substance? The same. The term "mole" is a synonym for "gram molecular weight". One mole of CH2O = 30.02598 grams.

Or inversely, one gram of formaldehyde = 0.0333044916436 moles.

How Gram Molecular Weight is used in TLV (Threshold Limit Value) calculations

Threshold limit values (TLVs), if we know the GMW of a substance, can let us easily convert between ppm and mg/m3 with the warning that the measurements assume that environment where the measurement is made is at 1ATM of pressure (sea level) and at 25°C. At other pressures and temperatures more adjustments need to be made to the simplified calculations shown below.

Any TLV expressed in mg/m3 = (gram molecular weight of substance) x (TLV in ppm) / 24.45

Any TLV expressed in ppm = 24.45 x (TLV in mg/m3) / (gram molecular weight of substance)

where 24.5 is a constant that equals the volume in liters of one mole (or one GMW) of a gas or vapor at 1 ATM of pressure at a temperature of 25C. For other temperatures the molecular weight must be re-calculated using the gas laws: V=(RT/P) where V=volume, R is the ideal gas constant, T is temperature in Kelvins, P is pressure in mm of hg.

Background about Gram Molecular Weight, Moles, Avogrado's Constant, and Fork Union Military Academy's Captain Peterson

In high school chemistry at Fork Union Military Academy Captain Peterson (ca 1959-1960) taught us that

Avogrado's number, 6.0221413 x 1023

is defined as the mass of one mole (one gram molecular weight) of any substance. He also used as an equivalent term "gram molecule" or "gram molecular weight" for "mole" but Peterson is long retired and gram-molecule has lost popularity to a somewhat different term "gram atom".

One gram-atom or "gat.", a somewhat different idea, is the quantity of any substance that contains Avogrado's number of atoms.

Peterson, when he, along with the science teacher, was not busy building a still in the top floor chemistry lab, was an exciting teacher who was inclined put a little more lycopodium powder into a can with a candle (bigger boom) or to cut a little larger piece of raw sodium metal to toss into the Fork Union sewer drain (which was tremendously exciting). When a spider was slowly spinning its way down over his desk, Peterson calmly opened a cylinder of raw chlorine gas that he had handy - just a little squirt, that's all. The spider turned white and the students, choking on chlorine, all jumped out of the classroom windows.

Online calculator converts among μg/L, μg/m3, ppmV and % concentrations

The U.S. EPA provides "EPA On-Line Tools for Site Assessment Calculation" at including a calculator that converts measurements among various scales such as μg/L, μg/m3, ppmV and %. However regrettably formaldehyde is not among the gases included in the EPA's calculator. We have asked that the EPA add that substance.


Formaldehyde Outgassing from Clothing & Soft goods: Exposure Limits

According to the New York Times, the most stringent (but voluntary) industry standards for exposure to formaldehyde were established in Japan, as follows:

References: is an independent publisher of building, environmental, and forensic inspection, diagnosis, and repair information for the public - we have no business nor financial connection with any manufacturer or service provider discussed at our website.

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