Characterization of seasonal indoor and outdoor bioaerosols in the arid environment of El Paso, Texas.Introduction Bioaerosols are particles or chemicals of biological origin that occur naturally and are then suspended in the air (Pastuska, Paw, Lis, Wlazlo, & Ulfig, 2000), such as bacteria, fungi Fungi (fŭn`jī), kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites, symbionts, or saprobes (see saprophyte). , protozoa, pollen, and animal dander animal dander See Dander. (Law, Chau, & Chan, 2001). Studies have shown a positive relationship between bioaerosol concentrations and the presence of symptoms corresponding to sick building syndrome sick building syndrome n. An illness affecting workers in office buildings, characterized by skin irritations, headache, and respiratory problems, and thought to be caused by indoor pollutants, microorganisms, or inadequate ventilation. and building-related illness (Cooley, Wong, Jumper, & Straus, 1998; Curtis et al., 2000; Jaakkola et al., 2002; Jarvis & Morey, 2001; Meyer et al., 2003; Park, Schleiff, Attfield, Cox-Ganser, & Kreiss, 2004; Pommer et al., 2004; Toivola, Nevalainen, & Alm, 2004). Outdoor bioaerosol concentrations fluctuate greatly depending on the environment and are directly dependent on meteorological conditions Noun 1. meteorological conditions - the prevailing environmental conditions as they influence the prediction of weather environmental condition - the state of the environment like temperature, relative humidity relative humidity n. The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage. , wind speed, exposure to ultraviolet light Ultraviolet light A portion of the light spectrum not visible to the eye. Two bands of the UV spectrum, UVA and UVB, are used to treat psoriasis and other skin diseases. , and so on. The highest concentrations have been shown to occur during the summer and fall, and lower concentrations during the winter (Adhikari, Sen, Gupta-Bhattacharya, & Chanda, 2004; Wilson & Straus, 2002). For indoor bioaerosol concentrations, environmental conditions are more stable, although still influenced by building heating, ventilation, and air-conditioning. Currently available research provides limited information about indoor seasonal bioaerosol concentrations (Chew, Rogers, Burge, Muilanberg, & Gold, 2003; Hyvarinen, Meklin, Jantunen, Nevalainen, & Moschandreas, 2001; Jones & Harrison, 2004; Lin & Li, 2000; Lugauskas, Svestyle, & Uleviscius, 2003). Several studies have assessed bioaerosol concentrations in different settings and seasons of the year. Green and co-authors (2003) studied single-family residences for indoor fungal fungal /fun·gal/ (fun´g'l) fungous; pertaining to fungi. fun·gal or fun·gous adj. 1. Of, relating to, resembling, or characteristic of a fungus. 2. and bacterial bioaerosol concentrations across seasons. Shelton and co-authors (2002) examined indoor and outdoor samples from buildings of various types located across the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. during a three-year period from 1996 to 1998. A Tempe, Arizona Tempe (pronounced /tɛm.'piː/) is a city in Maricopa County, Arizona, USA, with a population of 169,712 according to 2006 Census Bureau estimates. , study (Zhu et al., 2003) of indoor and outdoor airborne bacterial concentrations was conducted from August to December, sampling one office building at different sites for indoors and outdoors. Medrela-Kuder (2003) performed a seasonal repeated-measure study of a single building in Poland to determine indoor and outdoor fungal concentrations. The Medrela-Kuder study reported a seasonal variation, although no statistical analysis was performed to assess this difference. The objective of our study was to describe indoor and outdoor bioaerosol concentrations in the arid desert environment of the El Paso El Paso (ĕl pă`sō), city (1990 pop. 515,342), seat of El Paso co., extreme W Tex., on the Rio Grande opposite Juárez, Mex.; inc. 1873. , Texas, area in each season. The aim of the study was to perform repeated measures on houses across the four seasons and determine the dynamics of bioaerosol concentrations with respect to season and size. Methods [FIGURE 1 OMITTED] This study replicated and expanded upon a methodology described in a study that was conducted in Cincinnati, Ohio “Cincinnati” redirects here. For other uses, see Cincinnati (disambiguation). Cincinnati is a city in the U.S. state of Ohio and the county seat of Hamilton County. (Green et al., 2003). Indoor and outdoor bioaerosol samples (bacterial and fungal) were collected from a randomized ran·dom·ize tr.v. ran·dom·ized, ran·dom·iz·ing, ran·dom·iz·es To make random in arrangement, especially in order to control the variables in an experiment. convenience sample of 50 houses in the El Paso area. We identified houses through a solicitation solicitation In criminal law, the act of asking, inducing, or directing someone to commit a crime. The person soliciting another becomes an accomplice to the crime. The term also refers to the act of obtaining bribes, as well as to the crime of a prostitute who offers sexual for study participation that was sent to faculty, staff, and students at the University of Texas School of Public Health The Texas Legislature authorized the creation of a school of public health in 1947, but did not appropriate funds for the school until 1967. The first class was admitted in the Fall of 1969, doubled in the second year and doubled again in the third year, with continued grwoth over the , El Paso Campus and the University of Texas at El Paso The University of Texas at El Paso, popularly known as UTEP, is a public, coeducational university, and it is a member of the University of Texas System. The school is located on the northern bank of the Rio Grande, in El Paso, Texas, and is the largest university in the ; therefore, houses were not randomly selected. An informed-consent form provided by UTSPH was completed in accordance with its human subject protocols. We collected bioaerosol samples during a single visit in each of the four different seasons of the year: spring (March to May), summer (June to August), fall (September to November), and winter (December to February), from March 2005 through February 2006. Seasons were designated according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the traditionally accepted start dates of each season for the northern hemisphere, and an effort was made not to sample houses within five days of the ending or beginning of each season. Meteorological me·te·or·ol·o·gy n. The science that deals with the phenomena of the atmosphere, especially weather and weather conditions. [French météorologie, from Greek observations, however, were not used to confirm the start of seasons. The study was restricted to one-story houses that used evaporative-cooling technology and had no basement or attic. Samples were collected individually at each house on different days so all 50 houses were not sampled simultaneously. Over the course of the study, the number of participating houses decreased (spring, N = 50; summer, N = 48; fall, N = 47; winter, N = 38); this reduction was due to the decision of individual homeowners not to continue. We collected samples at the convenience of the residents; however, we required that the collection of repeated samples for individual houses occur during one of two sampling blocks, which were morning (8 a.m. to 12 p.m.) or afternoon (1 p.m. to 5 p.m.). That is, to maintain consistency, we collected repeated samples for all houses in the same time block as the initial sample. We collected bioaerosol samples in duplicate inside and outside of each house using two-stage ambient culturable sampler sampler, sample piece of needlework or embroidery, of silk, cotton, or worsted, for the preservation of some pattern or as an example of the ability of a child or a beginner. In museums and private collections there are samplers dating from as early as 1643. systems (Model TE-10-860, Tisch Environmental, Inc., Cleves, Ohio Cleves is a village located on the Ohio River in western Hamilton County, Ohio, United States. The population was 2,790 at the 2000 census. The village is named for John Cleves Symmes who lived here, laid out the original town site, and sold lots. ) (Andersen, 1976). These samplers divide organisms into two stages with some overlap, which represents the fine and coarse size ranges of the organisms. The coarse-stage bioaerosols (<8 [micro]m) were captured in the bottom sampler stage, representing particles likely to reach human lungs The human lungs are the human organs of respiration. Humans have two lungs, with the left being divided into two lobes and the right into three lobes. Together, the lungs contain approximately 1500 miles (2,400 km) of airways and 300 to 500 million alveoli, having a total . Two two-stage samplers were placed upon a tripod inside the house in the main living area, and two more were placed outside the main entrance of each house at a distance of two meters from the door, with identical procedures for both indoor and outdoor samples. Samplers were at one meter above the floor surface to simulate the human breathing zone (Hyvarinen et al., 2001; Pastuska et al., 2000; Sterling & Lewis, 1998). The two-stage samplers were calibrated cal·i·brate tr.v. cal·i·brat·ed, cal·i·brat·ing, cal·i·brates 1. To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument): to 28.3 L/min prior to each sampling trip (Dacarro, Picco, Grisolil, & Rodolfi, 2003). All two-stage samplers were autoclaved between homes, and they were completely wiped with alcohol and allowed to dry prior to beginning the next sampling to reduce contamination on site between samples. Malt Extract Agar Agar, in the Bible Agar (ā`gər), the same as Hagar. agar, substance obtained from seaweed agar (ä`gär, ā`–, ăg`är) (MEA MEA Multiple endocrine adenomatosis. See Multiple endocrine neoplasia. ) was used to determine fungal growth and Trypticase Soy Agar Trypticase soy agar is a bacterial growth medium. The medium contains enzymatic digests of casein and soybean meal which provides amino acids and other nitrogenous substances making it a nutritious medium for a variety of organisms. Dextrose is the energy source. (TSA TSA See tax-sheltered annuity (TSA). ) was used for the collection of bacteria. Using a total of four two-stage samplers, two 15- and two 10-minute samples were taken for both bacteria and fungi at both indoor and outdoor sampling sites, with indoor and outdoor sampling performed simultaneously. Duplicate samples at two different time periods for each culture media at both the indoor and outdoor sampling site assured the maximum amount of organisms without resulting in overloaded sample plates. The colony-forming units In microbiology, colony-forming unit (CFU) is a measure of viable bacterial numbers. Unlike in direct microscopic counts where all cells, dead and living, are counted, CFU measures viable cells. By convenience the results are given as per cubic meter Noun 1. cubic meter - a metric unit of volume or capacity equal to 1000 liters cubic metre, kiloliter, kilolitre metric capacity unit - a capacity unit defined in metric terms (CFUs/[m.sup.3]) were calculated for each media at each site using the greatest countable (mathematics) countable - A term describing a set which is isomorphic to a subet of the natural numbers. A countable set has "countably many" elements. If the isomorphism is stated explicitly then the set is called "a counted set" or "an enumeration". plate. For example, if the 15-minute samples were countable, then they were used; if the 15-minute samples were not countable, then the 10-minute samples were used. Sampling periods were longer than usual; however, since organism recoveries were low in our unreported preliminary study, the longer sampling periods were necessary. All media was prepared fresh to help prevent desiccation des·ic·ca·tion n. The process of being desiccated. des  ic·ca during the longer
sampling periods. The minimum and maximum recoverable organisms ranged
from 2 CFUs/[m.sup.3] to 706 CFUs/[m.sup.3]. The numbers of organisms
recovered were in a low frequency, so no positive-hole correlation was
conducted.
Meteorological conditions (temperature, relative humidity, and barometric ba·rom·e·ter n. 1. An instrument for measuring atmospheric pressure, used especially in weather forecasting. 2. Something that registers or responds to fluctuations; an indicator: pressure) were measured at indoor and outdoor sampling sites with a portable weather station (Traceable Digital Barometer Module, Calibration Control Company, Friendswood, Texas Friendswood is a city located in the U.S. state of Texas, partially in Galveston County and Harris County, within the Houston–Sugar Land–Baytown Metropolitan Area. As of the 2000 U.S. Census, the city population was 29,037. ). After sampling, fungal plates were incubated at 25[degree]C and bacterial plates at 35 [degree]C. Counts were obtained at 24 and 48 hours, colonies were enumerated This term is often used in law as equivalent to mentioned specifically, designated, or expressly named or granted; as in speaking of enumerated governmental powers, items of property, or articles in a tariff schedule. for each plate, and the total number of culturable CFUs/[m.sup.3] was calculated (Green et al., 2003; Meklin, Reponen, & Toivola, 2002). Fungal plates were incubated until the 10th day and counted after 1, 2, 5, and 10 days, to allow complete growth (e.g. Stachybotrys chartarum Stachybotrys chartarum (obsolete: Stachybotrys alternans and Stachybotrys atra) is a greenish-black mold that is commonly found outdoors and sometimes found in damp or flooded homes. , a slow-growing mold). Concentration (CFUs/[m.sup.3]) was calculated for each type of identifiable fungi and for each plate overall. Quality assurance and quality control were maintained through the use of aseptic aseptic /asep·tic/ (-tik) free from infection or septic material. a·sep·tic adj. Of, relating to, or characterized by asepsis. techniques. We used Staphylococcus aureus Staphylococcus au·re·us n. A bacterium that causes furunculosis, pyemia, osteomyelitis, suppuration of wounds, and food poisoning. Staphylococcus aureus Staphylococcus pyogenes (ATCC ATCC American Type Culture Collection, see there 25923) as positive control for the TSA recovery media and Candida albicans Candida albicans, n a pathogenic yeast, which is the causal agent of thrush, vaginal infections, and systemic candidiasis. Candida albicans (ATCC 10231) for the MEA media. Negative controls were empty plates of the different recovery media taken to the sampling site during collection. We used SAS (1) (SAS Institute Inc., Cary, NC, www.sas.com) A software company that specializes in data warehousing and decision support software based on the SAS System. Founded in 1976, SAS is one of the world's largest privately held software companies. See SAS System. Version 9.1 (2006) GLM GLM Global Language Monitor GLM Global Marine (stock symbol) GLM Graduated Length Method (ski instruction) GLM Good Looking Mom (used in pediatric practices) GLM God Loves Me for all statistical analysis. Dependent variables were those of the different bioaerosol concentrations. Independent variables were the seasons, relative humidity, temperature, and barometric pressure. For statistical analysis, a repeated-measure analysis of variance test (ANOVA anova see analysis of variance. ANOVA Analysis of variance, see there ) was performed to determine the bioaerosols' distribution across seasons. Each house was a block, in which the measures were taken in a repeated manner by seasons. Repeated measure sampling allows for an analysis that takes into account the unique microbial microbial pertaining to or emanating from a microbe. microbial digestion the breakdown of organic material, especially feedstuffs, by microbial organisms. and meteorological conditions within each home, which in turn allows for seasonal comparisons that are not influenced by how high or low the baseline is for each home. We also analyzed covariance Covariance A measure of the degree to which returns on two risky assets move in tandem. A positive covariance means that asset returns move together. A negative covariance means returns vary inversely. to compare seasons, with meteorological conditions as covariables. A least-significant-difference t-test was used to determine potential significant variability between the four different seasons. Indoor-to-outdoor ratios were calculated and a least-significant-difference t-test was also performed to detect any variation across seasons. We calculated correlations coefficients to compare indoor to outdoor bioaerosol concentrations. We used a correlation coefficient Correlation Coefficient A measure that determines the degree to which two variable's movements are associated. The correlation coefficient is calculated as: to quantify the relationship among bioaerosol concentrations. We then compared all of the statistical analyses to significance at the .05 level. We performed an analysis of covariance to determine potential effects of different meteorological conditions taken during sampling: indoor temperature, outdoor temperature, indoor relative humidity, outdoor relative humidity, indoor barometric pressure, and outdoor barometric pressure. Results We evaluated every total bioaerosol concentration according to season and indoor/outdoor status (Figure 1). We found the same seasonal trends for both indoor and outdoor bioaerosol concentrations. Total bioaerosol concentrations were highest in winter and fall. Summer had the third-highest bioaerosol concentrations, and spring had the lowest bioaerosol concentrations. [FIGURE 1 OMITTED] Indoor and outdoor fine bacterial concentrations were the highest during winter and the lowest in spring (Table 1). We recovered the greatest concentrations of indoor and outdoor coarse-fungal concentrations during fall, and we recovered the smallest concentration in winter. Fall had the highest indoor and outdoor fine-fungal concentrations; spring and winter had the lowest concentrations. All bioaerosol concentrations, with the exception of coarse indoor fungi, were statistically different across the seasons. We calculated the indoor-to-outdoor ratio for the various organisms in each season (Table 1). Fine bacteria had the highest indoor-to-outdoor ratio. Fine and coarse fungi had a greater than one indoor-to-outdoor ratio only in winter. Indoor-to-outdoor bioaerosol ratios were not significantly different across seasons.
TABLE 1
Statistical Variation on Bioaerosol Concentrations (CFUs/[m.sup.3]),
by Season, After Adjustment for Meteorological Conditions
Bioaerosol Spring Mean Summer Mean Fall Mean
Concentrations (SD) Concentrations Concentrations
(SD) (SD)
Coarse
bacteria
Indoor [47.sub.b]([+ or -]60) [58.sub.b] [77.sub.ab]
([+ or -]75) ([+ or -]78)
Outdoor [95.sub.b]([+ or -]108) [78.sub.b] [88.sub.b]
([+ or -]105) ([+ or -]90)
Indoor/outdoor 0.92 ([+ or -]1.15) 1.48 1.75
ratio ([+ or -]2.58) ([+ or -]4.11)
Fine bacteria
Indoor [185.sub.c] [231.sub.c] [331.sub.b]
([+ or -]126) ([+ or -]190) ([+ or -]209)
Outdoor [118.sub.c] [208.sub.b] [257.sub.ab]
([+ or -]74) ([+ or -]227) ([+ or -]187)
Indoor/outdoor 2.05 ([+ or -]2.02) 2.02 1.80
ratio ([+ or -]2.75) ([+ or -]1.69)
Coarse fungi
indoor 8 ([+ or -]9) 11 22
([+ or -]15) ([+ or -]52)
Outdoor [18.sub.b] ([+ or -]23) [19.sub.b] [45.sub.a]
([+ or -]17) ([+ or -]79)
Indoor/outdoor 0.79 ([+ or -]1.94) 0.74 0.63
ratio ([+ or -]0.84) ([+ or -]0.89)
Fine fungi
Indoor [56.sub.c] ([+ or -]48) [105.sub.b] [156.sub.a]
([+ or -]101) ([+ or -]134)
Outdoor [60.sub.c] ([+ or -]53) [110.sub.b] [232sub.a]
([+ or -]85) ([+ or -]218)
Indoor/outdoor 1.09 ([+ or -]0.90) 1.01 0.80
ratio ([+ or -]0.58) ([+ or -]0.38)
Bioaerosol Winter Mean Concentrations (SD) p-Value
Coarse bacteria
Indoor [104.sub.] ([+ or -]133) p<.05
Outdoor [173.sub.a] ([+ or -]198) p<.05
Indoor/outdoor ratio 1.92 ([+ or -]6.34) p=.62
Fine bacteria
Indoor [426.sub.a] ([+ or -]207) p<.05
Outdoor [327.sub.a] ([+ or -]216) p<.05
Indoor/outdoor ratio 2.10 ([+ or -]2.17) p=.92
Coarse fungi
indoor 11 ([+ or -]28) p=.15
Outdoor [13.sub.b] ([+ or -]9) p<.05
Indoor/outdoor ratio 1.58 ([+ or -]5.34) p=.38
Fine fungi
Indoor [78.sub.bc] ([+ or -]103) p<.05
Outdoor [70.sub.bc] ([+ or -]49) p<.05
Indoor/outdoor ratio 1.25 ([+ or -]1.52) p=.14
Note: Adjustments were made for temperature, humidity, and
barometric pressure. Means with different subscripts within each row
differ significantly at [ALPHA] = .05
Our study examined the potential impact of meteorological factors on the various bioaerosol concentrations (Table 2). As expected, temperature was highest in summer and lowest in winter. Barometric pressure was highest during winter indoor and outdoor samples. Relative humidity was lowest in winter and highest in summer. We calculated ANOVA p-values to determine the level of variability for each meteorological condition across seasons. There was statistical significance in all of the meteorological conditions.
TABLE 2
Indoor/Outdoor Mean and Standard Deviation of Various Seasonal
Meteorological Conditions, 2005-2006
Meteorological Condition Spring
Temperature ([degrees]C)
Indoor [23.94.sub.b] ([+ or -]4.42)
Outdoor [25.04.sub.b] ([+ or -]6.81)
Barometricpressure (mmHg)
Indoor [877.12.sub.b] ([+ or -]6.06)
Outdoor [877.18.sub.b] ([+ or -]5.96)
Relative humidity (%RH)
Indoor [30.84.sub.c] ([+ or -]9.07)
Outdoor [27.00.sub.b] ([+ or -]7.35)
Meteorological Summer Fall
Condition
Temperature
([degrees]C)
Indoor [26.35.sub.a] [22.49.sub.c]
([+ or -]2.49) ([+ or -]2.95)
Outdoor [31.56.sub.a]([+ or -]4.68) [22.94.sub.b]
([+ or -]5.93)
Barometricpressure
(mmHg)
Indoor [878.10.sub.b] [881.91.sub.a]
([+ or -]10.70) ([+ or -]5.89)
Outdoor [878.sub.b] ([+ or -]10.69) [881.79.sub.a]
([+ or -]5.93)
Relative humidity
(%RH)
Indoor [52.04.sub.a] [38.11.sub.b]
([+ or -]12.59) ([+ or -]10.23)
Outdoor [35.74.sub.a] [32.62.sub.a]
([+ or -]12.88) ([+ or -]8.67)
Meteorological Condition Winter p-Value
Temperature ([degrees]C)
Indoor [19.45.sub.d]([+ or -]2.26) p<.05
Outdoor [16.50.sub.c]([+ or -]7.45) p<.05
Barometricpressure (mmHg)
Indoor [883.05.sub.a] ([+ or -]7.74) p<.05
Outdoor [883.05.sub.a] ([+ or -]7.74) p<.05
Relative humidity (%RH)
Indoor [27.37.sub.c] ([+ or -]3.77) p<.05
Outdoor [27.13.sub.b] ([+ or -]4.47) p<.05
Note: Means with different subscripts within each row differ
significantly at [alpha] = .05.
The analysis evaluated the potential effect that meteorological conditions had on the bioaerosol concentration with respect to household and season. The result showed that the several meteorological conditions had no effect on bioaerosol concentrations in this study. This study does not include an interaction or potential combined effect of two factors together. Most meteorological conditions demonstrated no relationship with the different bioaerosol concentrations. Barometric pressure for indoor and outdoor samples correlated to indoor coarse bacteria (p = .02). The study found a relationship between outdoor coarse bacterial concentrations and outdoor barometric pressure (p = .04) after adjusting for all of the meteorological conditions. Indoor temperature had a significant correlation with indoor fine bacteria (p = .03). No fungal concentrations demonstrated a significant relationship with the meteorological conditions. Table 3 describes the correlation of indoor and outdoor bioaerosol concentrations across seasons in CFUs/[m.sup.3] with correlations coefficients and the p-values. In spring, fine fungi and coarse fungi reported a statistically significant correlation between indoor and outdoor bioaerosol concentrations. In summer, most bioaerosols, with the exception of coarse bacteria, reported a significant correlation coefficient between indoor and outdoor concentrations. Fall had a significant correlation in fine fungi and bacteria. Winter had no statistically significant correlation. TABLE 3 Correlation of Indoor and Outdoor Bioaerosol Concentrations Across [Seasons.sub.a] Organism Spring Summer Fall Winter Coarse 0.22 (p 0.48 (p 0.33 0.28 (p bacteria = .13) < .05) (p < = .09) .05) Fine 0.39 (p 0.62 (p 0.58 0.06 (p bacteria < .05) < .05) (p < = .70) .05) Coarse 0.57 (p 0.77 (p 0.30 0.10 (p fungi < .05) < .05) (p < = .55) .05) Fine 0.71 (p 0.91 (p 0.88 0.33 (p fungi < .05) < .05) (p < < .05) .05) (a) Correlation coefficient is reported with p-values inside the parentheses. Discussion Our study builds upon the Green and coauthors (2003) study that was conducted in Cincinnati, Ohio, by utilizing similar methodologies while incorporating outdoor samples, size differentiation, and repeated measures. Our study found that organism size (i.e., fine and coarse) plays an important role in the results provided. Seasonality was a key factor in our study, which demonstrated that bioaerosol concentrations were different across the seasons. This result was similar to that of the Green and co-authors study; however, Green speculated that his study underestimated the effect of seasonality. In our study, summer had the highest significant correlation between indoor and outdoor samples. This is reasonable, since some individuals in El Paso open The El Paso Open was a golf tournament on the Nationwide Tour. It ran from 1990 to 1991. It was played at Coronado Country Club in El Paso, Texas. In 1991 the winner earned $25,000. windows so that evaporative evaporative pertaining to evaporation. evaporative loss loss of body water by evaporation of water from the body to the air; a heat control mechanism and a factor in water balance studies. coolers can reduce the temperature. This allows a greater interaction between indoor and outdoor bioaerosol concentrations. Differences in methodology between our study and the Shelton and co-authors study (2002) could explain the differences in results. Shelton and co-authors did not evaluate residences independently; instead, all building types were pooled into the common sample and analyzed together. The majority of the buildings that participated in the Shelton and co-authors study reported health complaints, visible fungal growth, and water damage, while the houses sampled in our study reported no health complaints or other problems associated with the home. Shelton and co-authors did not utilize repeated measure of the sample sites or size distribution of bioaerosols. Furthermore, they had a lower sample size (N ~ 15) for the southwest region. The Shelton and co-authors study reported that throughout the United States, fall and summer had the highest concentrations, and spring and winter had the lowest (Shelton et al., 2002). Our study found that winter had the greatest outdoor and indoor bioaerosol concentrations. This result also differs from a number of other studies conducted in non-arid locations (Boston [Chew et al., 2003], Finland [Hyvarinen et al., 2001], and Lithuania [Lugauskas et al., 2003]). The Shelton and co-authors study demonstrated fungal variability by seasons, which coincides with our study. The two studies also verified the degree of variability of bioaerosol concentrations by seasons, although the studies differed on the degree of seasonal variability. Even though the meteorological conditions for Tempe, Arizona are similar to those found in El Paso, the bacterial concentrations found in the Zhu and co-authors (2003) study were higher than those found in our study. However, Zhu and co-authors did not evaluate seasonality or differentiate bioaerosol size ranges. Zhu and co-authors (2003) concluded that relative humidity had the most influence on the outdoor bacterial concentration (Zhu et al., 2003). Our study contradicts the results from the Zhu and co-authors study due to the lack of statistical significance when the different meteorological conditions were added to the ANOVA analysis. We could account for this lack of significance in our study with the blocking analysis that we conducted, since the block-design analysis used a comparison among seasons after adjusting for the meteorological conditions within each house. In several studies, the results demonstrated that meteorological conditions had a major impact on the different constituents that comprise bioaerosol concentrations (Green et al., 2003; Shelton et al., 2002; Zhu et al., 2003). Many studies described relative humidity as a significant factor in bioaerosol concentrations. Several studies reported that a higher relative humidity favors microbial and fungal growth (Green et al., 2003; Lee & Jo, 2005; Ren, Jankun, Belanger, Bracken bracken or brake, common name for a tall fern (Pteridium aquilinum) with large triangular fronds, widespread throughout the world, often as a weed. , & Leaderer 2001; Shelton et al., 2002; Zhu et al., 2003). The majority of these studies did not sample using the same location across the seasons. Repeated-measure sampling allows for an analysis that takes into account the unique microbial and meteorological conditions within each home, which in turn allows for seasonal comparisons that are not influenced by how high or low the baseline is for each home. Differences in these various studies could be due to drastic meteorological changes between seasons with humid hu·mid adj. Containing or characterized by a high amount of water or water vapor: humid air; a humid evening. See Synonyms at wet. summers and freezing winters. El Paso has a very dry climate; the changes between seasons are not as radical when compared to the environmental conditions of other studies. Lee and co-authors (2006) investigated the culturability of airborne fungi from indoor and outdoor samples across three different seasons (spring, fall, and winter). The samples were taken from six different houses in the Cincinnati area. The study calculated indoor-to-outdoor ratios and correlations for the fungal concentrations. Lee and co-authors showed that winter was the only season to demonstrate higher indoor concentrations than outdoor concentrations of culturable fungi. By contrast, our study found this occurred a number of times across seasons and types of bioaerosols. The Lee and co-authors study found a statistically significant correlation between indoor and outdoor culturable fungi. Their study is comparable to our study because repeated measures were taken in both. The samples taken in their study demonstrated similar fungal concentrations to ours in that the highest concentrations were outdoors during fall. In our study, all of the seasons except winter demonstrated a significant correlation between indoor and outdoor fungal concentrations. The findings of our study demonstrate a difference from previous studies in which the samples were not taken as a repeated measure. Our study shows that seasonal variation plays an important role in the results. The main limitation of our study was the use of convenience sampling to obtain houses, which could have created a selection bias. It is possible that participants enrolled because of concerns regarding an existing issue that they did not disclose, and this could overestimate o·ver·es·ti·mate tr.v. o·ver·es·ti·mat·ed, o·ver·es·ti·mat·ing, o·ver·es·ti·mates 1. To estimate too highly. 2. To esteem too greatly. bioaerosol concentrations for our population. Another limitation was that some study participants discontinued dis·con·tin·ue v. dis·con·tin·ued, dis·con·tin·u·ing, dis·con·tin·ues v.tr. 1. To stop doing or providing (something); end or abandon: participation, especially during the last sampling period, which was winter. This resulted in a decreased power for statistical analysis. Conclusion Our study demonstrated the significance of seasonal variability among the bioaerosol concentrations in the El Paso region. During all of the seasons except winter, there was a significant correlation between indoor and outdoor bioaerosols concentrations. Our study contradicts other studies that have shown winter to have the lowest organism concentration, as our study found that concentrations were actually highest in winter. We also showed the importance of repeated measures when bioaerosol concentrations are sampled. Using this repeated measure, several meteorological conditions were not significant when analyzed. Acknowledgements: Our research was partially funded by Hot Projects, an initiative of the Paso del Norte Del Norte can refer to multiple things:
Flores (flōrəs), town (1990 est. pop. 2,200), capital of Petén department, N Guatemala. Flores was built on an island in the southern part of Lake Petén Itzá and on the site of the and Carla Alvarado at the University of Texas School of Public Health. Editorial support was provided by Susan Navarro and the Hispanic Health Disparities
Health disparities (also called health inequalities in some countries) refer to gaps in the quality of health and health care across racial, ethnic, and socioeconomic groups. Research Center (P20 MD000548-01 NIH/NCMHD). The authors do not have a competing financial interest in this work. Corresponding author: Shawn G. Gibbs, Assistant Professor, University of Texas Health Science Center, School of Public Health, 1100 N. Stanton, Suite 110C, El Paso, TX 79902. E-mail: shawn.g.gibbs@uth.tmc.edu. REFERENCES Adhikari, A., Sen, M.M., Gupta-Bhattacharya, S., & Chanda, S. (2004). Airborne viable, non-viable, and non-viable, and allergenic Allergenic A substance capable of causing an allergic reaction. Mentioned in: Echinococcosis fungi in a rural agricultural area of India: a 2-year study at five outdoor sampling stations. Science and the Total Environment, 326, 123-141. Andersen Samplers Inc: Operating Manual for Andersen Sampler Inc. (1976). Viable Particle Sizing Sampler, Atlanta, GA. Chew, G.L., Rogers, C., Burge, H.A., Muilenberg, M.L., & Gold, D. (2003). Dustborne and airborne fungal propagules represent a different spectrum of fungi with differing relations to house characteristics. Allergy, 58, 13-20. Cooley, J.D., Wong, W.C., Jumper, C.A., & Straus, D.C. (1998). Correlation between the prevalence of certain fungi and sick building syndrome. Occupational and Environmental Medicine, 55, 579-584. Curtis, L., Scheff, P.A., Hryhorczuk, D.O., Ramakrishnan, V., Wadden, R.A., & Perskkys V.W. (2000). Association of asthma symptoms and severity with indoor bioaerosols. Allergy, 55, 705-711. Dacarro, C., Picco, A.M., Grisolil, P., & Rodolfi, M. (2003). Determination of aerial microbiological contamination in scholastic sports environments. Journal of Applied Microbiology microbiology: see biology. microbiology Scientific study of microorganisms, a diverse group of simple life-forms including protozoans, algae, molds, bacteria, and viruses. , 95, 904-912. Green, C.F., Scarpino, P.V., & Gibbs, S.G. (2003). Assessment and modeling of indoor fungal and bacterial bioaerosol concentrations. Aerobiologia, 19, 159-169. Hyvarinen, A., Meklin, M.T., Jantunen, M., Nevalainen, A., & Moschandreas, D. (2001). Temporals and spatial variation of fungal concentrations in indoor air. Aerosol Science Aerosol Science Aerosols are characterized by a particle size distribution function (PSD). Most natural aerosols have a lognormal distribution. Aerosol formation and growth consists of 3 processes:
Jaakkola, M.S., Nordman, H., Piipari, R., Uitti, J., Laitinen, J., Karjalainen, A., Hahtola, P., & Jaakkola, J.K. (2002). Indoor dampness and molds and development of adult-onset asthma: a population based incident case-control study case-control study, n an investigation employing an epidemiologic approach in which previously existing incidents of a medical condition are used in lieu of gathering new information from a randomized population. . Environmental Health Perspectives, 110, 543-547. Jarvis, J.Q., & Morey, P.R. (2001). Allergic respiratory disease Noun 1. respiratory disease - a disease affecting the respiratory system respiratory disorder, respiratory illness adult respiratory distress syndrome, ARDS, wet lung, white lung - acute lung injury characterized by coughing and rales; inflammation of the and fungal remediation in a building in a subtropical sub·trop·i·cal adj. Of, relating to, or being the geographic areas adjacent to the Tropics. subtropical Adjective of the region lying between the tropics and temperate lands climate. Applied Occupational Environmental Hygiene, 16, 380-388. Jones, A.M., & Harrison, R.M. (2004). The effects of meteorological factors on atmospheric bioaerosol concentrations-a review. Science and the Total Environment, 326, 151-180. Law, A.K.Y., Chau, C.K., & Chan, G.Y.S. (2001). Characteristics of bioaerosol profile in office buildings in Hong Kong Hong Kong (hŏng kŏng), Mandarin Xianggang, special administrative region of China, formerly a British crown colony (2005 est. pop. 6,899,000), land area 422 sq mi (1,092 sq km), adjacent to Guangdong prov. . Build Environment, 36, 527-541. Lee, J.H., & Jo, W.K. (2005). Exposure to airborne fungi and bacteria while commuting in passenger cars and public buses. Atmospheric Environment The envelope of air surrounding the Earth, including its interfaces and interactions with the Earth's solid or liquid surface. , 39, 7342-7350. Lee, T., Grinshpun, S.A., Martuzevicius, D., Adhikari, A., Crawford, C.M., & Reponen, T. (2006). Culturability and concentration of indoor and outdoor airborne fungi in six single-family houses. Atmospheric Environment, 40, 2902-2910. Lin, W-H, & Li, C-S C-S Civil-Structural C-S Cheek-Shoulder (ASL) . (2000). Associations of fungal aerosols, air pollutants pollutants see environmental pollution. and meteorological factors. Aerosol Science and Technology, 32, 359-368. Lugauskas, A., Svestyte, L., & Ulevicius, V. (2003). Concentration and species diversity of airborne fungi near busy streets in Lithuanian urban areas. Annals an·nals pl.n. 1. A chronological record of the events of successive years. 2. A descriptive account or record; a history: "the short and simple annals of the poor" of Agricultural and Environmental Medicine, 10, 233-239. Medrela-Kuder, E. (2003). Seasonal variations in the occurrence of culturable airborne fungi in outdoor and indoor air in Cracow. International Biodeterioration & Biodegradation Biodegradation The destruction of organic compounds by microorganisms. Microorganisms, particularly bacteria, are responsible for the decomposition of both natural and synthetic organic compounds in nature. , 52, 203-205. Meklin, T., Reponen, T., Toivola, M., Koponen, V., Husman, T., Hyvarinen, A., & Nevalainen, A. (2002). Size distributions of airborne microbes in moisture-damaged and reference school buildings of two construction types. Atmospheric Environment, 36, 6031-6039. Meyer, H.W., Wurtz, H., Suadicani, P., Valbjorn, O., Sigsgaard, T., Gyntelberg, E & Members of a working group under the Danish mould mould, n See mold. mould mold. in buildings program (DAMIB). (2004). Molds in floor dust and building-related symptoms in adolescent school children. Indoor Air, 14, 65-72. Park, J.H., Schleiff, P.L., Attfield, M.D., Cox-Ganser, J.M., & Kreiss, K. (2004). Building-related respiratory symptoms can be predicted with semi-quantitative indices of exposure to dampness and mold. Indoor Air, 14, 425-433. Pastuska, J.S., Paw, U.K.T., Lis, D.O., Wlazlo, A., & Ulfig, K. (2000). Bacterial and fungal bioaerosol in indoor environment in Upper Silesia Upper Silesia See Silesia. , Poland. Atmospheric Environment, 34, 3833-3842. Pommer, L., Fick, J., Sundell, J., Nilsson, C., Sjostrom, M., Stenberg, B., & Andersson, B. (2004). Class separation of buildings with high and low prevalence of SBS See Small Business Server. by principal component analysis. Indoor Air, 14, 16-23. Ren, P., Jankun, T.M., Belanger, K., Bracken, M.B., & Leaderer, B.P. (2001). The relation between fungal progagules in indoor and house characteristics. Allergy, 56, 419-424. SAS Institute SAS Institute Inc., headquartered in Cary, North Carolina, USA, has been a major producer of software since it was founded in 1976 by Anthony Barr, James Goodnight, John Sall and Jane Helwig. . (2006). SAS (Version 9.1) [Computer software]. Cary, NC: SAS Institute, Inc. Shelton, B., Kirkland, K., Flanders, W., & Morris, G. (2002). Profiles of airborne fungi in buildings and outdoor environments in the United States. Applied Environmental Microbiology Environmental microbiology is the study of the composition and physiology of microbial communities in the environment. The environment in this case means the soil, water, air and sediments covering the planet and can also include the animals and plants that inhabit these areas. , 68, 1743-1753. Sterling, D.A., & Lewis, R.D. (1998). Pollen and fungal spores indoor and outdoor of mobile houses. Annals of Allergy, Asthma & Immunology immunology, branch of medicine that studies the response of organisms to foreign substances, e.g., viruses, bacteria, and bacterial toxins (see immunity). Immunologists study the tissues and organs of the immune system (bone marrow, spleen, tonsils, thymus, lymphatic , 80, 279-285. Toivola, M., Nevalainen, A., & Alm, S. (2004). Personal exposure to particles and microbes in relation to microenvironmental concentrations. Indoor Air, 14, 351-359. Wilson, S.C., & Straus, D.C. (2002). The presence of fungi associated with sick building syndrome in North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. zoological institutions. Journal of Zoo and Wildlife Medicine, 33(4), 322-327. Zhu, H., Phelan, P.E., Duan, T., Raupp, G.B., Fernando, H.J.S., & Che, F. (2003). Experimental study of indoor and outdoor airborne bacterial concentrations in Tempe, Arizona, USA. Aerobiologia, 19, 201-211. Did you know You can still register for NEHA's Annual Educational Conferences & Exhibition in Tucson, Arizona Tucson (pronounced /ˈtusɑn/, Spanish: Tucsón [tuk'son] , June 22-25. To register, please visit neha.org. For more information on the conference, please check out pages 7-22 in this issue of the Journal. Linda C. Mota, M.P.H. Shawn G. Gibbs, M.S., Ph.D. Christopher F. Green, M.S., Ph.D. Fernanda Payan Patrick M. Tarwater, M.S., Ph.D. Melchor Ortiz, M.S., Ph.D. |
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