Dieterich, M.F., Gieseler, M.E., Short, D.B., and Signorelli, R.T.

AbstractFormaldehyde , a group 1 carcinogen is a component of indoor air and may be used to assess overall indoor air quality. Measurements of formaldehyde were taken with a portable meter at various sites and compared. Levels ranging from 0.01 ppm to 0.18 ppm formaldehyde were recorded.

IntroductionFormaldehyde (CH2O) is a group 1 carcinogen and is categorized in the same group as benzene, arsenic, asbestos, and ionizing radiation. CH2O is a pungent, colorless, possible carcinogenic gas that occurs naturally and from man-made sources. Man-made sources of CH2O include adhesives, paint, plastics, textiles, pressed wood products (particle board, plywood panels), and fertilizers. It is also formed during the burning of organic materials and is found in tobacco smoke [1].  The toxic effects of formaldehyde exposure can be classified as follows: irritation of mucous membrane, contact dermatitis, teratogenicity, and carcinogenicity [1]. Irritating effects of CH2O exposure such as chest pain and coughing begin at 0.4 ppm. There are currently no national standards for indoor exposure in residential homes and businesses. The California Air Resources Board (CARB) has highly recommends that residential levels of CH2O remain well below 0.02 ppm. and the American Society for Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) recommend a level not to exceed 0.1 ppm.  In homes and offices, a major contributing source of CH2O is cleaning products. CH2O is found in cleaning products as a biocide, or is formed as a reaction product when Volatile Organic Compounds (VOCs) react with ozone in the surrounding atmosphere [2]. This study measures formaldehyde in various buildings and compares the results to other studies.

Field SamplingIndoor measurements of CH2O were collected in various locations at Robert Morris University, including an anatomy lab, and at one off-campus household. The sampling device used was a Formaldemeter htV by ENMET Corporation.

MethodA commercially available data logging electrochemical CH2O detector called the Formaldemeter 400 was employed to evaluate the domestic levels of formaldehyde indoors.

This device uses electrochemical sensing technology to measure airborne formaldehyde concentration, as well as ambient temperature and humidity levels. The formaldehyde concentrations were measured in parts per million (ppm) ranging from 0 to 10.00 ppm with resolution of 0.01 [3].

The Formaldemeter 400 uses a sampling frequency of 1 to 3 minutes, and analyzes the samples within 60 seconds. After each sample was collected, the device was turned off for a duration of 3-5 minutes to allow the detector to recover in between measurements (as specified by manufacturer’s manual). The device operates with a precision of 10%.

DiscussionIndoor air samples were collected at various buildings on RMU campus, at an off-campus home, and in the laboratory after a cat was dissected. The greatest number of samples was measured at the off-campus house and CH2O concentrations ranged from 0.01 to 0.18 ppm (see Table 1), with an average level of 0.64 ppm. The mean measurement recorded at the campus buildings was 0.02 ppm, and the mean measurement recorded after the cat was dissected in the laboratory was 0.74. The background level of CH2O for all sample sites ranged from 0.01-0.02 ppm. At the off-campus house, the levels of CH2O spiked after cleaning products were used. Our average CH2O level would have been approximately 0.04 ppm if not affected by the cleaning products. This average is comparable to a similar study that found a mean measurement 0.02 ppm CH2O in 179 homes [4].

This increase in CH2O levels may be due to either (i) presence of biocide, (ii) oxidation of VOCs, or (iii) a possible interference from phenols, alcohols, or aldehydes with the monitor [5]. If this study were conducted in the future, the chemicals in the cleaning products would have to be researched to determine if interfering agents are present.

References[1] Hess-Kosa, K. (2002) Indoor Air Quality. Lewis Publishers, April 2012.  [2] Hahn, S.  ,Schneider, K., Gartiser, S., Heger, W., and Mangelsdorf, I. (2010) Consumer exposure to biocides-identification of relevant sources and evaluation of possible health effects. Environmental Health: A Global Access Science Source, Vol. 9, No. 1 Article number 7.  [3] ENMET Formaldemeter htV: http://www.enmet.com/pdf/Formalda_htVManual.pdf, April 2012.

[4] Sekine, Y.,Fukuda, M.,Takao, Y., ,Ozano, T.,Sakuramoto, H., and Wang, K.W. (2011) Simultaneous removal of formaldehyde and benzene in indoor air with a combination of sorption-and decomposition-type air filters. Environmental Technology, Volume 32, Issue 16, 1, pp. 1983-1989, April 2012.

[5] NIOSH Formaldehyde Short Term Study: http://www.cdc.gov/nceh/ehhe/trailerstudy/pdfs/Formaldehyde%20Instrument%20Report_331-05b.pdf, April 2012.

ResultsTable 1 shows the measurements of CH2O in each room, ranging from minimum to maximum levels. Figure 2 compares the average concentrations of CH2O for all three locations.

Table 1: Highest levels of CH2O are indicated by the triangle symbols and lowest levels are indicated by the square symbol.

Figure 1: Mean concentration of CH2O at each location