Michael L. Muilenberg

Dustborne and airborne fungal propagules represent a different spectrum of fungi with differing relations to home characteristics

Background: Exposure to fungi is often assessed by culturing floor dust or air samples. Our objective was to evaluate the relationships between dustborne and airborne fungi and to identify factors that modify these relationships.

Monthly measurements of indoor allergens and the influence of housing type in a northeastern US city

Background: We examined seasonal variation of dust‐mite (Der f 1 and Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergens in Boston, while adjusting for other covariates. Limited data are available on seasonal patterns of indoor allergen concentrations for different geographic regions in the USA. Understanding within‐home seasonal variation of allergens is important epidemiologically and clinically.

Mold and Endotoxin Levels in the Aftermath of Hurricane Katrina: A Pilot Project of Homes in New Orleans Undergoing Renovation

Background After Hurricane Katrina, many New Orleans homes remained flooded for weeks, promoting heavy microbial growth. Objectives A small demonstration project was conducted November 2005–January 2006 aiming to recommend safe remediation techniques and safe levels of worker protection, and to characterize airborne mold and endotoxin throughout cleanup. Methods Three houses with floodwater lines between 0.3 and 2 m underwent intervention, including disposal of damaged furnishings and drywall, cleaning surfaces, drying remaining structure, and treatment with a biostatic agent. We measured indoor and outdoor bioaerosols before, during, and after intervention. Samples were analyzed for fungi [culture, spore analysis, polymerase chain reaction (PCR)] and endotoxin. In one house, real-time particle counts were also assessed, and respirator-efficiency testing was performed to establish workplace protection factors (WPF). Results At baseline, culturable mold ranged from 22,000 to 515,000 colony-forming units/m3, spore counts ranged from 82,000 to 630,000 spores/m3, and endotoxin ranged from 17 to 139 endotoxin units/m3. Culture, spore analysis, and PCR indicated that Penicillium, Aspergillus, and Paecilomyces predominated. After intervention, levels of mold and endotoxin were generally lower (sometimes, orders of magnitude). The average WPF against fungal spores for elastomeric respirators was higher than for the N-95 respirators. Conclusions During baseline and intervention, mold and endotoxin levels were similar to those found in agricultural environments. We strongly recommend that those entering, cleaning, and repairing flood-damaged homes wear respirators at least as protective as elastomeric respirators. Recommendations based on this demonstration will benefit those involved in the current cleanup activities and will inform efforts to respond to future disasters.

Differential effects of outdoor versus indoor fungal spores on asthma morbidity in inner-city children.

BACKGROUNDnAlthough sensitization to fungal allergens is prevalent in inner-city children with asthma, the relationship between fungal exposure and morbidity is poorly understood.nnnOBJECTIVEnWe examined relationships between fungal sensitization, exposure, and asthma morbidity in inner-city children.nnnMETHODSnParticipants were 5 to 11 years old and enrolled in the Inner-City Asthma Study. This report includes the subset of children with at least 1 positive skin test (PST) response to a fungal allergen extract; for these children, indoor and outdoor airborne culturable fungi levels were measured at baseline and throughout the 2-year study. Asthma morbidity measures were collected prospectively. The primary outcome was symptom days per 2 weeks.nnnRESULTSnAt baseline, children with a PST response to a fungal allergen extract had significantly more symptom days compared with those without a PST response to any fungal allergen extract (6.3 vs 5.7 days per 2 weeks, P = .04). During the study, increases in total fungal exposure and indoor Penicillium species exposure were associated with increases in symptom days and asthma-related unscheduled visits. Indoor exposures to total fungi and to Penicillium species were associated with significant increases in unscheduled visits, even after controlling for outdoor fungal levels. Adverse effects associated with exposure to a specific fungus were stronger among children with PST responses to that fungal allergen extract compared with those seen in children with negative skin test responses.nnnCONCLUSIONnOutdoor fungal exposure is primarily associated with increased asthma symptoms and increased risk of exacerbations in this population.

Mouse allergens in urban elementary schools and homes of children with asthma

BACKGROUNDnThe association between allergens in schools and childhood asthma has not been well studied, particularly in the United States.nnnOBJECTIVEnTo investigate allergen exposure in schools compared with homes with a specific focus on children with asthma.nnnMETHODSnDust samples were collected from 46 rooms in 4 urban elementary schools (northeastern United States) and from 38 student bedrooms. Samples were analyzed for cat (Fel d 1), dog (Can f 1), cockroach (Bla g 2), dust mites (Der f 1/Der p 1), and mouse urinary protein (MUP). Questionnaires identified students with physician-diagnosed asthma.nnnRESULTSnCat and dog allergens were detectable in most school samples (96% and 78%, respectively), but at low levels. Cockroach allergen was detectable in only 11% of school samples. Mouse allergen was detectable in 89% of school samples, with 68% having MUP levels greater than 0.5 microg/g. In contrast, MUP was detectable in only 26% of bedroom samples. Matched classroom and home samples from 23 asthmatic students showed higher geometric mean MUP levels in the classroom vs the home (6.45 microg/g vs 0.44 microg/g, P < .001). However, there were lower geometric mean dust mite (Der f 1) levels in the classroom vs the home (0.04 microg/g vs 0.66 microg/g, P < .001).nnnCONCLUSIONSnThere are significantly higher levels of MUP but lower levels of Der f 1 in schools vs homes. It is important to recognize that children with asthma may encounter varying levels of allergens in environments outside the home, such as schools.

The School Inner-City Asthma Study: Design, Methods, and Lessons Learned

Background. Children spend a significant amount of time in school. Little is known about the role of allergen exposure in school environments and asthma morbidity. Objectives. The School Inner-City Asthma Study (SICAS) is a National Institutes of Health (NIH)-funded prospective study evaluating the school/classroom-specific risk factors and asthma morbidity among urban children. Methods/results. This article describes the design, methods, and important lessons learned from this extensive investigation. A single center is recruiting 500 elementary school-aged children, all of whom attend inner-city metropolitan schools. The primary hypothesis is that exposure to common indoor allergens in the classroom will increase the risk of asthma morbidity in children with asthma, even after controlling for home allergen exposures. The protocol includes screening surveys of entire schools and baseline eligibility assessments obtained in the spring prior to the academic year. Extensive baseline clinical visits are being conducted among eligible children with asthma during the summer prior to the academic school year. Environmental classroom/school assessments including settled dust and air sampling for allergen, mold, air pollution, and inspection data are collected twice during the academic school year and one home dust sample linked to the enrolled student. Clinical outcomes are measured every 3 months during the academic school year. Conclusion. The overall goal of SICAS is to complete the first study of its kind to better understand school-specific urban environmental factors on childhood asthma morbidity. We also discuss the unique challenges related to school-based urban research and lessons being learned from recruiting such a cohort.

Projected Carbon Dioxide to Increase Grass Pollen and Allergen Exposure Despite Higher Ozone Levels

One expected effect of climate change on human health is increasing allergic and asthmatic symptoms through changes in pollen biology. Allergic diseases have a large impact on human health globally, with 10–30% of the population affected by allergic rhinitis and more than 300 million affected by asthma. Pollen from grass species, which are highly allergenic and occur worldwide, elicits allergic responses in 20% of the general population and 40% of atopic individuals. Here we examine the effects of elevated levels of two greenhouse gases, carbon dioxide (CO2), a growth and reproductive stimulator of plants, and ozone (O3), a repressor, on pollen and allergen production in Timothy grass (Phleum pratense L.). We conducted a fully factorial experiment in which plants were grown at ambient and/or elevated levels of O3 and CO2, to simulate present and projected levels of both gases and their potential interactive effects. We captured and counted pollen from flowers in each treatment and assayed for concentrations of the allergen protein, Phl p 5. We found that elevated levels of CO2 increased the amount of grass pollen produced by ∼50% per flower, regardless of O3 levels. Elevated O3 significantly reduced the Phl p 5 content of the pollen but the net effect of rising pollen numbers with elevated CO2 indicate increased allergen exposure under elevated levels of both greenhouse gases. Using quantitative estimates of increased pollen production and number of flowering plants per treatment, we estimated that airborne grass pollen concentrations will increase in the future up to ∼200%. Due to the widespread existence of grasses and the particular importance of P. pratense in eliciting allergic responses, our findings provide evidence for significant impacts on human health worldwide as a result of future climate change.

Exposures to Molds in School Classrooms of Children with Asthma

Students spend a large portion of their day in classrooms which may be a source of mold exposure. We examined the diversity and concentrations of molds in inner‐city schools and described differences between classrooms within the same school.

Efficacy of integrated pest management in reducing cockroach allergen concentrations in urban public housing.

The efficacy of residential interventions to reduce cockroach allergens in public housing developments was evaluated over months of follow-up. Repeated measurements were collected from 39 apartments, with longitudinal analyses used to evaluate changes over time. Bla g 1 kitchen concentrations were reduced 71% and bed concentrations 53% (86% and 70% for Bla g 2, respectively) by 6 months post-intervention, after which concentrations began to increase. Apartments with higher concentrations were usually in poorer condition and benefited most from pest management efforts. Intensive interventions can significantly reduce the allergen burden in public housing apartments, but intervention efforts must be sustained.

Predictors of indoor exposure to mouse allergen in urban and suburban homes in Boston

Background:u2002 Mouse allergen exposure is prevalent among urban children with asthma. Little is known about mouse allergen exposure in children at risk for the development of allergic diseases.