1.11 Museum Survey of Indoor PAN, Nitrogen Dioxide, Nitric Acid, Chlorinated Hydrocarbons, Sulfur Dioxide, and Total Reduced Sulfur
 

Daniel Grosjean and Associates
Daniel Grosjean
Mohamed W. M. Hisham
Edwin Williams
Sucha Parmer
Period of Activity: 6/87 to 4/89

Project Abstract
Peroxyacetyl nitrate (PAN), nitric acid (HNO3), and chlorinated hydrocarbons have never been monitored indoors. Nitrogen dioxide, sulfur dioxide, and total reduced sulfur have been measured but only in a few museum environments. Since all four pol lutants have serious materials damage potential, they were surveyed. Nitrogen dioxide will be the subject of a larger survey planned in the future since it is known to be more univer sally distributed both nationally and internationally than the other three pollutants.

Major Findings
(Reflected in two separate final reports, "Air Pollution in Southern California Museums: Nitrogen Dioxide, Peroxyacetyl Nitrate, Nitric Acid, and Chlorinated Hydrocarbons," and "Air Pollution in Southern California Museums: Sulfur Dioxide, Total Reduced Sulfur, Chlorinated Hydrocarbons, and Photochemical Oxidants.")

The air pollutants surveyed were ubiquitous and could be measured in indoor air at all nine locations. At all but one museum, indoor concentrations of NO2, PAN, and nitric acid were comparable to outdoor levels of these pollutants.

At six of the nine institutions surveyed, indoor levels of chlorinated hydrocarbons chlorinated hydrocarbons were higher than outdoor concentrations, thus pointing to indoor sources. At the three remain ing locations, indoor levels of chlorinated compounds were comparable to out door levels.

Indoor levels of NO2, PAN, nitric acid (all cases) and chlorinated hydrocarbons (in the absence of indoor sources) closely followed outdoor variations, thus indicating rapid in door-outdoor air exchange. Indoor concentrations thus reflected (a) outdoor air quality, with its spatial and diurnal changes, and (b) building air exchange characteristics.

In terms of air exchange characteristics, the structures surveyed can be divided into three groups: no air conditioning (HVAC) and unrestricted indoor/outdoor (I/O) air ex change (three museums), HVAC with some degree of I/O air exchange (three museums), and HVAC with carbon filtration (three museums). Not surprisingly, indoor levels of air pollu tants were essentially identical to outdoor ones in institutions lacking HVAC systems.

At institutions with HVAC, I/O ratios for NO2, PAN, and nitric acid were sub stantially higher than those measured earlier for ozone.

Our observations suggest that HVAC systems, which remove ozone substantially, may not be effective to remove NO2, PAN, chlorinated hydrocarbons, and perhaps other pollutants as well.

Of the four locations equipped with filtration equipment, only two yielded expected low indoor pollutant levels and correspondingly low indoor/outdoor ratios.

While outdoor and indoor levels of SO2 (and TRS ) were low at three museums exam ined, I/O ratios for SO2 were high and averaged 0.89. Of the three museums surveyed, one (Gene Autry Museum Gene Autry Museum;) was equipped with an HVAC and chemical filtration sys tem chemical filtration sys tem;. This system was not efficient at removing low levels of SO2 (<5ppb). H2S concentra tions were very low, 16-46 x 10-3 ppb at El Pueblo and <6 x 10-3 ppb at the other two museums.

Primary Publications
Hisham, M. W. M., and D. Grosjean, "Air Pollution in Southern California Museums: Nitrogen Dioxide, Peroxyacetyl Nitrate, Nitric Acid, and Chlorinated Hydro carbons," Final Report to the Getty Conservation Institute by Daniel Grosjean and Associates, April 1989.

ABSTRACT-Air pollution damage to museum collections has emerged as a major issue in art conservation. While outdoor air pollution including acid deposition has been recognized as a threat to cultural property for many years, damage to works of art due to exposure to indoor air pollution is now receiving increasing atten tion. Following Getty Conservation Institute (GCI)-sponsored studies of indoor ozone, formaldehyde, and particulate matter, we have carried out a comprehensive survey of the air pollutants nitrogen dioxide(NO2), peroxy acetyl nitrate (PAN), chlorinated hydrocarbons (methyl chloroform, carbon tetrachloride, tetrachloroethylene) and nitric acid (HNO3) at nine Southern California museums. These pollutants and the nine institutions surveyed were selected so as to en compass a broad range of situations, thus giving general applicability to the findings of our study.

Hisham, M. W. M., and D. Grosjean, "Indoor Air Pollutants in Southern California Museums," American Chemical Society, Division of Environmental Chemistry, Miami, Florida, September 10-15, 1989.

ABSTRACT-Damage to works of art resulting from exposure to air pollutants has received increasing attention from museum curators and art conservation scientists. Recent studies have documented the presence of ozone in museum air and the corre sponding fading of organic colorants exposed in the dark to 0.3 ppm of ozone. Another potentially damaging air pollutant, formaldehyde, has been the object of a recent survey. Very little is known regarding the nature and levels of other air pollu tants in museum settings. Thus, a survey of nine institutions was carried out during the summer of 1988 and involved intensive measurements of the following air pollutants:

nitrogen dioxide (NO2)

peroxyacetyl nitrate (PAN, CH3C(O)OONO2)

nitric acid (HONO2)

the chlorinated hydrocarbons, carbon tetrachloride (CCl4), methyl chloroform (1,1,1-trichloroethane, CH3CCl3), and tetra chloro ethylene (Cl2C=CCl2)

The nine organizations surveyed included several art museums, a natural history museum, a major library, an archaeological museum, and historical buildings including adobe structures. These organizations were selected to include a diversity of collections, of outdoor-indoor air exchange characteristics, and of locations within the Southern California area, which exhibits a strong air pollution gradient from coastal to inland regions. At each organization, measurements were carried out over a two-week period and included (a) round-the-clock measurements, using a gas chromatograph (GC) outfitted with two sampling lines and two injection loops, of indoor and outdoor levels of PAN and of chlorinated hydrocarbons, (b) round-the-clock measurements of indoor and outdoor levels of NO2 using a chemiluminescent NOx analyzer, and (c) off-line collection of indoor and outdoor samples and subsequent liquid chromatography analysis for NO2 ; (as nitrite after collection on trietha nolamine-coated cartridges trietha ), and for nitric acid (as nitrate following collection on nylon filters). A limited number of formaldehyde and acetaldehydemea surements were also carried out by liquid chromatographyfollowing collec tion on DNPH-coated cartridges. At each museum, GC measurements were carried out at a single location, while off-line samples were collected at 8-12 different locations.

Hisham, M. W. M., and D. Grosjean, "Indoor Air Levels of Nitrogen Dioxide, Peroxyacetyl Nitrate (PAN), Nitric Acid, and Chlorinated Hydrocarbons in Southern California Museums," 1989 Pacific Conference on Chemistry and Spectroscopy, Division of Atmospheric Chemistry, Pasadena, California, October 18-21.

ABSTRACT-Measurements were made concerning the concentration levels of NO2, PAN, HNO3, CCl4, CH3CCl3, and C2Cl4 in nine museums. The pollutants were ubiquitous in indoor air at all locations. At six of the nine museums surveyed, indoor concentrations of chlorinated hydrocarbons (but not PAN, NO2, or HNO3) exceeded outdoor levels, thus indicating indoor sources for these compounds. Highest indoor recorded levels during our study were 120 ppb for NO2, 14 ppb for PAN, and 10 ppb for HNO3. Actual indoor/outdoor (I/O) ratios reflected the buildings' air exchange characteristics: Indoor levels of air pollutants were essentially identical to outdoor ones at locations lacking air conditioning (HVAC). At institutions with HVAC systems, some degree of air exchange (I/O range 0.6-0.8 for PAN) was observed. Of the three locations equipped with HVAC with carbon filters only one yielded the expected low indoor pollutant levels and correspondingly low I/O ratios (e.g. I/O = 0.08 for PAN). For the other two build ings the I/O ratio is somewhat high (e.g. 0.7 for PAN).

Hisham M. W. M., and D. Grosjean, "Air Pollution in Southern California Museums: Sulfur Dioxide, Total Reduced Sulfur, Chlorinated Hydrocarbons, and Photochemical Oxidants," Final Report to the (Conservation at the Getty) Institute prepared by Daniel Grosjean and Associates, Inc., March 1990.

ABSTRACT-A survey of the indoor and outdoor concentrations of air pollutants has been carried out at three Southern California museums: El Pueblo State Historical Park, Southwest Museum, and the Gene Autry Western Heritage Museum. At the three museums, sulfur dioxide (SO2)and total reduced sulfur (TRS, total reduced sulfur which includes hydrogen sulfide (H2S), mercaptans, sulfides, carbonyl sulfide, and carbon disulfide) were measured using continuous analyzers (SO2 and TRS), off-line samples collected for 24 hours (SO2 and TRS), and passive badges (H2S). As an extension of our previous survey (see above, "Air Pollution in Southern California Museums: Nitrogen Dioxide, Peroxyacetyl Nitrate, Nitric Acid, and Chlorinated Hydrocarbons"), the air pollutants measured at the newly constructed Gene Autry Museum also included ozone, nitrogen dioxide, peroxyacetyl nitrate (PAN), and the chlorinated hydrocarbons, methylchloroform (CH3CCl3) and tetrachloro ethylene (C2Cl4).

The survey yielded some 600 data points each for ozone, NO2, PAN, and the chlorinated hydrocarbons, which were present in indoor and outdoor air at all locations. Indoor and outdoor SO2 and TRS were below the 5 ppb detection limits of the con tinuous analyzers, but could be detected using off-line samples. Indoor maxima were 175 ppb for NO2, 77 ppb for ozone, 0.7 ppb for PAN, 1.2 ppb for C2Cl4, <6.3 ppb for CH3CCl3, 2.5 ppb for SO2, 1.4 ppb for TRS (both from 24 hr. samples), and 46 x 10-3 ppb for H2S (from 6-7 month samples).

The overall data set was further examined in terms of diurnal variations diurnal variations;, indoor/outdoor (I/O) concentration ratios, and museum I/O air exchange characteristics including HVAC and chemical filtration. The experimental data are consistent with the following conclusions:

a. While outdoor and indoor levels of SO2 (and TRS) were low at all three museums, I/O ratios for SO2 were high and averaged 0.89. Of the three museums surveyed, one (Gene Autry Museum) was equipped with HVAC and chemical filtration system. This system was not efficient in removing low levels of SO2 (<5ppb). H2S concentrations were very low, 16-42 x 10-3ppb at El Pueblo and <6 x 10-3 ppb at the other two museums.

b. Indoor levels and I/O ratios for chlorinated hydrocarbons pointed out to significant indoor sources, as we have already observed at six of the nine institutions included in our previous study.

c. I/O ratios for the air pollutants with outdoor sources, i.e., ozone, PAN, and NO2, showed considerable variations, from low values of 0.02-0.33 at locations without influx of outdoor air to high values of 0.85-0.88 at locations experiencing high influx of outdoor air, e.g. the Gene Autry Museum buffer zone area. Segregation of the buffer zone data into "door open" and "door closed" subsets clearly show an in crease in indoor levels of ozone and NO2 when the door has been opened and a corresponding decrease (by dilution) for the chlorinated hydrocarbons. The same effect was observed, though to a smaller extent, in the nearby Conservation Room.

d. Using PAN as an example of outdoor pollutant, I/O ratios obtained in this study have been compared to those measured in our previous survey. Of the ten institutions surveyed in Southern California to date, eight exhibit high I/O ratios of 0.60-1.00. Of the four museums equipped with HVAC and chemical filtration, only two, Huntington's Scott Gallery (one location) and the Gene Autry Museum (two loca tions) yielded the expected low I/O ratios.

e. While the adverse effects of ozone, SO2, and to some extent NO2 on museum collections are documented, no data are available regarding possible damage due to PAN or chlorinated hydrocarbons. The very low concentrations of H2S measured in this study indicate that there were no significant sources of H2S at the three museums sur veyed, of that H2S emissions, if any, were offset by rapid removal to indoor surfaces.

 

Grosjean, D., E. L. Williams II, and M. W. M. Hisham, "Removal of Air Pollutants by Carbon and Permanganate-Alumina Filtration Systems in Museums: A Case Study," Final Report to the (Conservation at the Getty) Institute by Daniel Grosjean and Associates, Inc., [4526 Telephone Road, Suite 205, Ventura, California 93003]. September 1990.

ABSTRACT-Because of the significant difference in operating costs between car bon and permanganate-alumina filtration systems, and considering the lack of consensus regarding the relative performance of the two types of sorbents, this study compares the efficiency of carbon and permanganate-alumina under identical, "real-world" conditions. This case study was carried out at the Gene Autry Western Heritage Museum, which had been included in our previous studies. and whose chem ical filtration system includes both carbon and permanganate-alumina. The pollutants measured were ozone, nitrogen dioxide, peroxyacetyl nitrate (PAN), and two chlorinated hydrocarbons. The results of this study indicate that carbon and per manganate-alumina had similar efficiencies for removal of the air pollutants studied: indoor/outdoor pollutant concentration ratios indicated that both sorbents performed well for removal of ozone and PAN, moderately well for removal of nitrogen dioxide, and rather poorly for the removal of the two chlorinated hydrocarbons. The database compiled in this study does not indicate an advantage in using the more ex pensive permanganate-alumina instead of, or in addition to, activated carbon for the control of airborne gaseous pollutants.

Hisham, M. W. M., and D. Grosjean, "Air Pollution in Southern California Museums: Indoor and Outdoor Levels of Nitrogen Dioxide, Peroxyacetyl Nitrate, Nitric Acid, and Chlorinated Hydrocarbons," Environmental Science and Technology, Vol. 25, N 5, 1991, pp. 857-862.

ABSTRACT-See abstract to the Final Report cited above.

Hisham, M. W. M., and D. Grosjean, "Sulfur Dioxide, Hydrogen Sulfide, Total Reduced Sulfur, Chlorinated Hydrocarbons and Photochemical Oxidants in Southern California Museums," Atmospheric Environment, Vol. 25a, N 8, 1991, pp. 1497-1505.

ABSTRACT-See abstract to the Final Report cited above.