Endotoxin, cat, and house dust mite allergens in electrostatic cloths and bedroom dust

Passive Bioaerosol Samplers: A Complementary Tool for Bioaerosol Research. A Review

Bioaerosols consist of airborne particles of biological origin. They play an important role in our environment and may cause negative health effects. The presence of biological aerosol is typically determined using active samplers. While passive bioaerosol samplers are used much less frequently in bioaerosol investigations, they offer certain advantages, such as simple design, low cost, and long sampling duration. This review discusses different types of passive bioaerosol samplers, including their collection mechanisms, advantages and disadvantages, applicability in different sampling environments, and available sample elution and analysis methods. Most passive samplers are based on gravitational settling and electrostatic capture mechanism or their combination. We discuss the agar settle plate, dustfall collector, Personal Aeroallergen Sampler (PAAS), and settling filters among the gravity-based samplers. The described electrostatics-based samplers include electrostatic dust cloths (EDC) and Rutgers Electrostatic Passive Sampler (REPS). In addition, the review also discusses passive opportunity samplers using preexisting airflow, such as filters in HVAC systems. Overall, passive bioaerosol sampling technologies are inexpensive, easy to operate, and can continuously sample for days and even weeks which is not easily accomplished by active sampling devices. Although passive sampling devices are usually treated as qualitative tools, they still provide information about bioaerosol presence and diversity, especially over longer time scales. Overall, this review suggests that the use of passive bioaerosol samplers alongside active collection devices can aid researchers in developing a more comprehensive understanding of biological presence and dynamics, especially over extended time scales and multiple locations.

Effect of air filtration on house dust mite, cat and dog allergens and particulate matter in homes

Background

Methods

Results

Conclusions

Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin, PM10, and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners in the homes of children age 6-12 years with asthma in the Yakima Valley, Washington. All families received asthma education while intervention families also received two HEPA cleaners (child's bedroom, living room). We collected 14-day integrated samples of endotoxin in settled dust and PM₁₀ and PM_10-2.5 in the air of the children's bedrooms at baseline and one-year follow-up, and used linear regression to compare follow-up levels, adjusting for baseline. Seventy-one families (36 HEPA, 35 control) completed the study. Baseline geometric mean (GSD) endotoxin loadings were 1565 (6.3) EU/m² and 2110 (4.9) EU/m² , respectively, in HEPA vs. control homes while PM₁₀ and PM_10-2.5 were 22.5 (1.9) μg/m³ and 9.5 (2.9) μg/m³ , respectively, in HEPA homes, and 19.8 (1.8) μg/m³ and 7.7 (2.0) μg/m³ , respectively, in control homes. At follow-up, HEPA families had 46% lower (95% CI, 31%-57%) PM₁₀ on average than control families, consistent with prior studies. In the best-fit heterogeneous slopes model, HEPA families had 49% (95% CI, 6%-110%) and 89% lower (95% CI, 28%-177%) PM_10-2.5 at follow-up, respectively, at 50th and 75th percentile baseline concentrations. Endotoxin loadings did not differ significantly at follow-up (4% lower, HEPA homes; 95% CI, -87% to 50%).

Comparison of ERMI results for dust collected from homes by an electrostatic cloth and by the standard vacuum method

The Environmental Relative Moldiness Index (ERMI) is a scale used to compare mold contamination levels in U.S. homes. To create the ERMI scale, a nationally representative set of U.S. homes was selected (n = 1,096). From each of these homes, a standard vacuum-dust sample was collected and then 36 common molds, the 26 Group 1 and 10 Group 2 molds, as grouped for forming the ERMI metric, were quantified using quantitative PCR assays. However, in investigations of mold in homes, it is not always practical or even possible to collect dust using the standard vacuum method. Therefore, we performed a comparative study of dust samples collected in the same homes (n = 151) by the standard vacuum method and by an electrostatic cloth (EC) method. First, floor dust was collected by vacuuming a 2 m² area in the living room and a 2 m² area in a bedroom, directly adjacent to the sofa or bed, for 5 min each with a Mitest sampler-fitted vacuum. Second, immediately after the collection of the vacuum dust sample, an EC dust sample was collected by wiping above-floor horizontal surfaces in the living room and bedroom. Then, the ERMI analysis of each sample was performed by a commercial laboratory. The results showed the average concentrations of 33 of the 36 ERMI molds were not significantly different in the vacuum and EC samples. Also, the average summed logs of the Group 1 molds, Group 2, or ERMI values were significantly (p < 0.001) correlated between the vacuum and EC samples. Logistic regression indicated that an EC sample could identify homes in the highest ERMI quartile 96% of the time by using the same ERMI value cutoff as vacuum sample ERMI value cutoff and 35% of samples proved to be false positives. When it is not practical to obtain the standard vacuum-dust sample, an EC sample can provide a useful practical alternative for ERMI analyses.

Metagenomic Characterization of Indoor Dust Bacterial and Fungal Microbiota in Homes of Asthma and Non-asthma Patients Using Next Generation Sequencing

Background

The exposure of house occupants to indoor air pollutants has increased in recent decades. Among microbiological contaminants, bacterial and fungal aerosols remain poorly studied and the debate on the impact of these aerosols on respiratory health is still open. This study aimed to assess the diversity of indoor microbial communities in relationship with the health of occupants.

Methods

Measurements were taken from dwellings of 2 cohorts in Brittany (France), one with children without any pathology and the other with children and adults with asthma. Thirty dust samples were analyzed by next generation sequencing with a 16S and 18S targeted metagenomics approach. Analysis of sequencing data was performed using qiime 2, and univariate and multivariate statistical analysis using R software and phyloseq package.

Results

A total of 2,637 prokaryotic (589 at genus level) and 2,153 eukaryotic taxa were identified (856 fungal taxa (39%) and 573 metazoa (26%)). The four main bacterial phyla were identified: Proteobacteria (53%), Firmicutes (27%), Actinobacteria (11%), Bacteroidetes (8%). Among Fungi, only 136 taxa were identified at genus level. Three main fungal phyla were identified: Ascomycota (84%), Basidiomycota (12%) and Mucoromycota (3%). No bacterial nor fungal phyla were significantly associated with asthma versus control group. A significant over representation in control group versus asthma was observed for Christensenellaceae family (p-value = 0.0015, adj. p-value = 0.033). Besides, a trend for over representation in control group was observed with Dermabacteraceae family (p-value = 0.0002, adj. p-value = 0.815).

Conclusions

Our findings provide evidence that dust samples harbor a high diversity of human-associated bacteria and fungi. Molecular methods such as next generation sequencing are reliable tools for identifying and tracking the bacterial and fungal diversity in dust samples, a less easy strategy for the detection of eukaryotes at least using18S metagenomics approach. This study showed that the detection of some bacteria might be associated to indoor air of asthmatic patients. Regarding fungi, a higher number of samples and sequencing with more depth could allow reaching significant signatures.

Reliability and Correlation Between Indoor Allergen Concentrations from Vacuumed Surface Samples and Electrostatic Dust Collectors

OBJECTIVES

Most studies on indoor allergen exposure used vacuumed surface samples for quantification. One alternative is electrostatic dust collectors (EDCs), which sample previously airborne settled dust. The aim of this study was to compare allergen quantification using two different sampling methods, with respect to repeatability, and to determine how well the results agree with one another.

METHODS

Four times a year, measurements were made from samples that were either collected from the vacuuming of surfaces, or from EDCs, from 20 German day-care centers totaling 167 rooms. Overall, 504 vacuumed samples collected from smooth floors, 435 samples from carpets, 291 samples from upholstered furniture and beds, and 605 EDC samples were analyzed using six fluorescence enzyme immunoassays recognizing Fel d 1, Can f 1, Mus m 1, domestic mite (DM), Dermatophagoides pteronyssinus (Dp), and Tyrophagus putrescentiae (Tp) antigens. Variances and correlations among the repeat measurements over the course of the year within each sample type, and the correlations between surface samples and the corresponding EDC samples were calculated.

RESULTS

Repeat measurements over the year correlated significantly with one another. However, only Fel d 1, Can f 1, and DM in the EDC samples; DM, Dp, Tp, and Fel d 1 in the upholstered furniture samples; and DM in the carpet samples show representative results of single measurements according to their variance ratios (within-room/between-room variance <1). The highest correlation between surface and EDC samples was found for Fel d 1 on the upholstered furniture (r 0.52), followed by Can f 1 on the upholstered furniture and Can f 1 on carpets (r 0.47 and 0.45, respectively). The maximum correlation for mite antigens was between carpet samples and EDC (DM r 0.27, Dp r 0.33). Mus m 1 and Tp antigens for the most part did not correlate to the EDC results.

CONCLUSIONS

Both vacuumed dust from upholstered furniture and EDC samples were suitable for repeatable quantification of several allergens in day-care centers within a year. However, there was little agreement among the different collection methods, especially for Mus m 1 and certain mite antigens. Therefore, the method and location used for collection may greatly influence allergen exposure assessment and study results.