Table II. Atmospheric Loss Rates for Aldehydes and Ketones 108k[OH], a
substrate
S-’
2.0=
CH3COCH3 CH3COCHzCH3 CH~COCHZCH(CH~)~ CHaCHO CPH&HO
quantum yield for dissociation under atmospheric conditions is only 0.21 (20),which implies an increased relative importance of OH reaction as a loss process for simple aldehydes.
108k
.-p1’
12.4
3.5 52.0
12.5 12.5d
64.0 84.0
39.3 43.3
[OH] = 4 X IO6 molecules ~ m - calculated ~ ; for solar zenith angle of 26’ (21). Calculation using solar flux data of Peterson ( 1 7 ) for solar zenith angle of 30‘. Using k(OH acetone) = 5 X cm3 molecule-’ s-l from ref
+
6. Assumed to be the same as methyl ethyl ketone.
compound together with a radical fragment. Reaction with 0 2 to produce a- or P-diketones does not compete with this decomposition. These data allow a reasonable model to be made for the mechanism of the OH-initiated degradation of typical ketonic solvents in ambient air. The rate constants for reaction of OH with MEK and MIK have also been determined. All carbonyl compounds absorb UV radiation near the short-wavelength cutoff of the solar spectrum a t ground level, and it is of interest to compare the rates of direct photolysis of these compounds with the rate of OH attack. Table I1 shows such a comparison for selected aldehydes and ketones using solar flux data (17)for a solar zenith angle of 30’ and a corresponding OH concentration of 4 X lo6 molecules ~ m - The ~ . photolysis rates, k , are calculated from the overlap of the solar spectrum with the absorption spectra of the substrate molecules ( 1 8 ) .The quantum yields for photodissociation in air a t 1 atm are not well known (19) and are arbitrarily assumed to be unity; the values of k , are therefore upper limits only. If this assumption is realistic, photolysis is the dominant atmospheric loss process for acetone and MEK, whereas MIK is removed primarily by OH reaction. For the simple aldehydes, OH reaction and photolysis apparently occur a t comparable rates. However recent work on CHsCHO photolysis indicates that the overall
Literature Cited (1) Demerjian, K. R.; Kerr, J. A,; Calvert, J. G. Adu. Environ. Sei. Technol. 1974,4, 1. (2) Baldwin, A. C.; Barker, J. R.; Golden, D. M.; Hendry, D. G. J . Phys. Chem. 1977,81, 2483. (3) Batt, L. Int. J . Chem. Kinet. 1979,11,977. (4) Golden, D. M. NBS Spec. Publ. (US.) 1979,557, 51. (5) Cox, R. A. J. Photochem. 1974,3,175;Int. J. Chem. Kinet. Symp. 1 1975,379. (6) Cox, R. A,; Derwent, R. G.; Williams, M. R. Environ. Sci. Technol. 1980, 14, 57. (7) Atkinson, R.; Darnall, I(. R.; Lloyd, A. C.; Winer, A. M.; Pitts, J. N., Jr. Adu. Photochem. 1979,11, 375. (8) Darnall, K. R.; Carter, W. P. L.; Winer, A. M.; Lloyd, A. C.; Pitts, J. N., Jr. J . Phys. Chem. 1976, do, 1948. (9) Batt, L.; McCulloch, R. M. Int. J. Chem. Kinet. 1976,8, 911. (10) Carter, W. P. L.;Lloyd, A. C.; Sprung, J. L.; Pitts, J. N., Jr. Int. J . Chem. Kinet. 1971,11, 45. (11) Cox, R. A,; Derwent, R. G.; Kearsey, S. V.; Batt, L.; Patrick, K. G. J . Photochem. 1980,13, 149. (12) Batt, L. In “Reactions of Alkoxy Radicals Relevant to Atmospheric Chemistry,” European Symposium on Physico-Chemical Behavior of Atmospheric Pollutants, Ispra, Oct 16-18, 1979. (13) Carter, W. P. L.; Darnall, K. R.; Lloyd, A. C.; Winer, A. M.; Pitts, J. N., Jr. Chem. Phys. Lett. 1976, 42, 22. (14) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. J . Phys. Chem. 1978,82, 132. (15) Winer, A. M.; Lloyd, A. C.; Darnall, K. R.; Pitts, J. N., Jr. J. Phys. Chem. 1976,80, 1635. (16) Solly, R. K.; Golden, D. M.; Benson, S. W. Int. J . Chem. Kinet. 1970,2, 381. (17) Peterson, J. T. Research Triangle Park, NC, June 1976, EPA Report EPA-600/4-76-025. (18) Calvert, J. G.; Pitts, J. N., J r . “Photochemistry”; Wiley: New York, 1966. (19) Llovd, A. C. ‘TroDosuheric Chemistrv of Aldehvdes’ in N B S Spec. Publ. (U.S.)1979,-557, 27. (20) Weaver, J.; Meagher, J.; Heicklein, J. J . Photochem. 1972, 6, 111. (21) Derwent, R. G.; Hov, 8. A.E.R.E. Report R 9434; H. M. Stationery Office: London, 1979.
Received for review September 16,1980. Accepted January 13,1981. This work was sponsored by the U.K. Department of the Environment. K.F.P. thanks the S.R.C. for awarding a CASE studentship.
Room-to-Room Variations in Concentration of Respirable Particles in Residences Carole Ju Bureau of Environmental Epidemiology and Occupational Health, New York State Health Department, Albany, New York 12208
John D. Spengler” Department of Environmental Health Sciences, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts 02 1 15
Since individuals can spend from 60% to 90% of their time indoors (1, 2), indoor air quality is important in the assessment of the health effects of air pollution. With the growing national attention to energy conservation, methods to conserve fuel for home heating are being applied to private dwellings. These focus on sealing the home as tightly as possible, reducing the passage of air, and thus pollutants, in and out of the structure. In addition, the growing use of wood and possibly coal as home heating fuels will be reflected in a change in the type of particulates generated indoors. As part of the Harvard Six City Study ( 3 ) ,concentrations of mass respirable particles, SO2, NO*, and sulfates are being monitored inside and outside several residences and public buildings. The indoor residential environment is being mon592
EnvironmentalScience & Technology
itored in the room that is most used for family activities, usually the living room or den. Spengler et al. ( 4 )found that indoor mean levels were higher than outdoor means, with cigarette smoking a large contributor to indoor levels. They found large differences in indoor concentrations between cities and also within cities, reflecting the importance of indoor sources and ventilation rates of each structure. Myers ( 5 )addressed the question of whether, within a single home, concentrations of respirable particles are comparable from room to room. One might expect levels to be higher near sources of particles, for example, in the kitchen where meals are prepared, in rooms with fireplaces, or areas where people smoke. Also, the total suspended particulate, mostly of outdoor origin, has been measured to drop off in residences with 0013-936X/81/0915-0592$01.25/0
@
1981 American Chemical Society
Concentrations of respirable particles were measured in private homes to determine whether levels in different rooms were comparable. Four homes, each with an outdoor monitor and three to five indoor monitors, were tested for 24-h periods on 30 sampling days, Respirable particles were collected on preweighed Teflon filters with Harvard-EPRI sampling pumps equipped with 10-mm nylon cyclones. An analysis of variance was done on the indoor data for each home to detect variations between rooms. Two homes showed significant differences between rooms ( P < 0.05), and two other homes
showed no significant differences. However, the magnitudes of the between-room differences were small, and in all but one home the mean value for the living room approximated the mean of all indoor values to within 5%. Comparisons across the four homes by analysis of variance revealed that the outdoor concentrations were comparable but that indoor concentrations varied greatly, indicating the importance of indoor particulate sources and characteristics of individual structures in determining indoor levels.
increasing distances from doors and windows (6).With three to four monitors in each home, five homes were sampled on 7 days. Myers concluded that levels of respirable particles were similar in different rooms of the home, especially in homes without smokers. Because of the small sample size and the large variability in the flow rate of the sampling equipment used, confidence in these results was not great. The present study was undertaken to investigate the same question of whether concentrations of respirable particles vary between rooms of the home, using more accurate sampling equipment and an increased sample size. An attempt was made to monitor homes with different physical setups and indoor sources of particles (smokers, fireplaces, etc.).
Procedure Since a large number of samples were to be collected in each home, homes were chosen so that one member of the household could be responsible for changing the filters and running the sampling equipment. The four homes were in the Boston, MA, metropolitan communities of Brighton, Newton, Waltham, and Watertown. Brighton is a community in the city of Boston; Newton and Watertown are suburbs contiguous to Brighton; Waltham is a more western suburb. Although located in four different communities, all of the homes are within a circle of 6-mi diameter. None of the homes was near any major point sources. The homes were located in residential sections of these towns and not approximate to commercial districts or roads with heavy traffic. Home locations are shown in Figure 1,and the four homes are described in Table I. A target of 30 sampling days per home was chosen. Samples were collected for 24 h every other day so that all days of the week would be represented. The sampling period was the winter months from late November 1979 to early February 1980. A schedule was set up in mid-November so that all homes would be monitored on the same 30 days, except for interruptions due to travel plans and holidays. The Harvard-EPRI personal sampling pumps (7) with 10-mm nylon cyclones were used to collect 24-h samples of respirable particles; the pumps were operated by being plugged into household power sockets. The cyclones conform to the criteria of the American Conference of Governmental Industrial Hygienists (AGGIH) (8) for respirable particles, collecting no particles of >10 pm, 25% of 5-pm particles, 50% of 3.5-pm particles, and 90% of particles of 5 2 pm. Each home was supplied with a rotameter that had been calibrated with an NBS-certified bubble meter and a table of flow rates for each rotameter reading. Pumps were adjusted to a flow rate of -1.7 pm a t the beginning of each 24-h sampling period (ca. 8 a.m.). Ending flow rates were taken after sampling, and a linear decrease in flow was assumed for volume calculation. Samples were collected onto Fluoropore FALPO 3700 filters with 1-pm pores. Net weight gains on filters were determined on Cahn electrobalances according to the protocol of the Harvard Six City Study (9). Errors in particle mass concentrations from the weighing procedure and flow measurement were experimentally determined to be 8-11% (10).
I, 2. 3. 4.
Watertown Brighton Woltham Newton
Figure 1. Home
d
b , = 1 ku
locations.
Data f o r Individual Homes The data from the four homes are summarized in Table 11. The complete data set is available as supplementary material. (See paragraph a t end of text regarding supplementary material.) In all homes the indoor average concentrations of respirable particles were higher than the outdoor mean values. The mean difference ranged from a low of 4 pg/m3 for the large Victorian Watertown home to a high of 15 pg/m3 for the wood-burning home in Waltham which had an occasional pipe smoker. The mean ratio of the indoor averaged concentration to the outdoor concentration was between 2.03 and 2.3 for three homes but was only 1.57 for the Watertown home. For the 106 home sample days, only 6 days had outdoor values exceeding the indoor averaged concentrations. All homes had at least 1 day when the indoor-to-outdoor ratio exceeded 5. Before turning to the analysis of the data, it is interesting to look at the data from the individual homes to see the effects of unusual occurrences against the background of normal daily patterns. For the Watertown home, December 24,1979, was the day before Christmas and several of the occupants were away. The dining room was not used, no meals were cooked, and the second-floor bedroom was unoccupied. For this day, the uniformity of room concentrations is remarkable. The indoor concentrations ranged from 20.8 to 22.8 pglm3. The outdoor concentration was 22.7 pg/m3 and the I / O ratio was 0.96. On the same day (December 24, 19791, for the Newton residence indoor respirable particle concentrations were much higher than normal. The home was occupied for 4.5 h with 30 Volume 15, Number 5, May 1981 593
Table I. Characteristics of Homes Monitored residence (voi of unit)
characteristics
smoking
monitor locations
Watertown (30 000 ft3) (5 adults)
3-story house gas heat gas stove 2 fireplaces woodstove in 2nd-floor bedroom
no
front porch (outside) kitchen living room dining room 2nd-floor bedroom 3rd-floor hall
Brighton (6500 ft3) (2 adults)
4-rOOm apartment (1st floor) electric heat electric stove
no
outside living room kitchen living room bedroom
Waltham (15 000 ft3) (2 adults)
2-story house oil heat electric stove woodstove in dining room
5 pipefulls/day
Newton (20 000 ft3) (2 adults, 2 children)
2-story house gas heat electric stove fireplace in living room
2 cig/daya
outside kitchen living room dining room 2nd-floor bedroom side p o k h (outside) kitchen living room 2nd-floor bedroom
a
Smoker was required to smoke only next to an open chimney flue.
Table II. Mean Levels of Respirable Parficles (pg/m3) in Four Homes a residence
no. of days
Watertown
25
11.5 (2.4-22.7)
Brighton Waltham
30 30
Newton
30
10.9 (2.4-18.3) 19.4 (7.2-67.6) 19.9 (7.4-68.9) 23.3 (8.1-80.7) 12.5 (4.8-24.0)* 25.6 (7.2-61.1) 28.8 (9.4-64.6) 27.9 (6.0-59.1) 27.6 (1 1-59.9) 10.3 (3.7-21.6) 16.8 (6.3-49.0) 17.3 (6.7-57.2) 19.6 (9.3-79.3)
a
outdoor
kitchen
17.5 (8.2-36.2)
The concentration range is in parentheses.
livlng room
12.7 (5.6-23.6)
Room-to-Room Variations T o extrapolate indoor exposures from a 24-h measurement in a single location, we tested the assumption that respirable particles are well mixed within a home. Our null hypothesis was that concentrations do not vary from room to room. T o test this hypothesis for each home, we used a two-way analysis of variance with replacement of missing values by the leastsquares technique of Yates ( 1 1 ) . The statistical analysis is summarized in Table 111. For all homes the day-to-day variation was highly significant ( P < 0.01). For the first two homes, the probability that the room-to-room variations were due to chance is 0.05) that the differences are due to chance, and for the Newton household this probability is -5% ( P = 0.05). Environmental Science & Technology
bedroom
3rd floor
indoor av
13.4 (3.7-23.4)
15.2 (8.4-23.0) 20.9 (7.6-72.4) 27.5 (8.4-60.3) 17.9 (7.6-61.8)
21 samples only.
people enjoying a party. The higher levels reflect activities such as cooking, smoking, and use of the fireplace. The indoor concentrations ranged between 49 and 80 pg/m3 while the outdoor level was 24.5 pg/m3. For the Waltham household, December 2,1979, stands out for its high values. On this day the house was occupied by about a dozen people, including several smokers, and a turkey was roasted for several hours. With an outdoor level of 15.7 pg/m3, the indoor concentrations averaged 60 pg/m3 and ranged between 59 and 63 pg/m3. This home is heated in the winter almost exclusively by a wood stove in the dining room. However, on December 7,1979, the wood stove was not used a t all, and no smoking occurred in the house all day. Concentrations in all rooms were unusually low on this day. The outdoor concentration was 5.1 pg/m3 and the indoor concentrations ranged from 6 to 11pg/m3.
594
dining room
16.9 (6.3-29.6) 15.2 (8.1-22.9)
Table 111. Analysis of Variance of Between-Room Differences in Concentrations of Respirable Particles a residence
no. of days
no. of samples
Watertown
25
125
11.1
