Population structure and environmental features often capture major axes of genetic variation in many species. Yet the impacts of human activity often remain unquantified. For domesticated species that rely on human activity for survival and dispersal, human movements and cultural differences may play key roles patterning genetic diversity. Maize is a staple crop of enormous cultural importance to indigenous peoples of the Americas, but cannot survive or disperse without farmers. Using publicly available genotyping and passport data from almost 2,000 traditional maize varieties, more than 500 whole genome sequences of humans from Mexico, and indigenous linguistic maps, we quantify anthropogenic effects on maize genetic diversity in the Americas. Maize shows very little overall structure, highlighting the effectiveness of indigenous farmers in moving and mixing maize populations. While principal components of maize diversity show meaningful correlations to human genetic diversity, our linear modeling suggests little additional impact of human population structure beyond shared geography. Though differences in maize diversity are often patterned by language locally, we find only weak genome-wide effects at larger spatial scales. Despite the relatively weak global signal of anthropogenic effects, linguistic GWAS, outlier FST analyses, and selection scans identified loci associated with specific languages. Leveraging landscape-level sequencing data, we highlight how anthropogenic factors have shaped patterns of maize genetic diversity across Mesoamerica. ### Competing Interest Statement The authors have declared no competing interest. U.S. National Science Foundation, https://ror.org/021nxhr62, 2305694, 2307175 CIMMYT

Introduction Priestia megaterium and P. aryabhattai are closely related bacteria of industrial relevance whose species status has been debated. Previous studies have not sufficiently resolved this taxonomic issue.Methods To clarify the taxonomy of these two species, we compared 190 publicly available genomes, including 12 new high-quality assemblies. In addition, metagenomic and phenotypic data were examined for species-level differences.Results Whole-genome phylogenies consistently resolved two monophyletic clades corresponding to the named taxa. Mean digital DNA-DNA hybridization between the clades was 64%, supporting separation at the species level, whereas the mean average nucleotide identity was 95.2%, indicative of an ambiguous boundary-range. Several newly isolated strains showed recombinant genomic signatures, suggesting gene flow during an ongoing speciation. Metagenomic surveys indicated distinct ecological patterns, with differences in abundance across tropical and temperate regions. Using complete assemblies, we identified species-specific loci and designed PCR primers capable of discriminating the two taxa.Discussion Our results support the taxonomic classification of P. megaterium and P. aryabhattai as distinct species and provide novel molecular markers to facilitate ecological, industrial, and diagnostic studies.

Background House dust mite (HDM) sensitization is a leading cause of allergic rhinitis and asthma worldwide, with Dermatophagoides pteronyssinus, Dermatophagoides farinae, and Blomia tropicalis being the primary allergenic species typically associated with indoor environments. Even effective multicomponent interventions creating an HDM-free indoor environment are often insufficient to prevent allergy, as HDM exposure may also occur outdoors. Objective To assess the potential for outdoor HDM exposure, we applied air biomass sequencing and metagenomic techniques to detect HDM DNA in both indoor and outdoor bioaerosols, offering an alternative to conventional dust sampling methods. Methods We used 2 data sets in this study: (1) a global data set comprising 1,171 outdoor air samples collected across 33 countries in open air environments and (2) a data set of indoor (n = 161) and outdoor (n = 156) air samples collected across 156 apartments from 106 locations in Singapore. All air samples were collected by drawing 24,000 to 36,000 L of air using SASS3100 air samplers; all samples were processed identically. Species-level taxonomic classification was performed using Kaiju software aligned to the National Center for Biotechnology Information nonredundant database, with a minimum threshold of 40 reads per taxon. Results Analysis of 1,171 global outdoor air samples revealed D pteronyssinus as the most prevalent HDM species; it was detected in 208 samples, with abundance increasing from temperate toward equatorial regions. In Singaporean households, D pteronyssinus was found in 58.4% of indoor samples and 21.2% of nearby outdoor samples, with high median DNA read counts outdoors suggesting that exposure to HDM is not limited to domestic environments. B tropicalis and D farinae were also detected in Singapore, albeit at lower frequencies. Conclusion Our findings highlight the need to expand environmental allergen surveillance beyond household dust to include ambient and outdoor air, particularly in tropical climates.

Abstract Background Emerging evidence suggests that maternal-prenatal gut microbiome disturbances shape offspring allergic outcomes through modulation of the in utero immune environment. Yet, no comprehensive clinical studies in human mother–offspring dyads have deconvoluted the maternal-prenatal gut microbiome and systemic immune-metabolome signatures underlying offspring allergic predisposition. Methods We performed a longitudinal nested case–control study involving 128 well-characterized mother–offspring dyads from defined cases (offspring with atopic dermatitis (AD); n = 64) and controls (offspring without AD; n = 64). Maternal stool and blood samples were collected at multiple time points during gestation for multi-omic profiling. Structural and functional gut microbiome composition was characterized via metagenomic sequencing, while systemic metabolome and serum immune milieu were profiled using targeted plasma metabolomics and Olink proximity extension assays, respectively. In offspring early-life, stool samples were collected longitudinally up to 6 months of age for gut microbiome and metabolome analyses. Results Mothers of AD infants exhibited longitudinal enrichments of gut Klebsiella pneumoniae, Roseburia intestinalis, Clostridioides difficile and Bilophila sp. 4_1_30, alongside depletions in gut Clostridium sp. CAG:678, Romboutsia timonensis, Akkermansia muciniphila, Blautia hansenii and Alistipes ihumii during pregnancy. These taxonomic shifts were associated with systemic metabolomic alterations, including elevated branched-chain amino acids and immune-related metabolites (e.g., creatine, ornithine), and a concurrent pro-inflammatory TH2-skewed immunological milieu marked by increased interleukin-4 (IL-4) and IL-5 and decreased CXCL11. In early life, AD infants harbored a dysbiotic gut microbiome characterized by persistent enrichments of potentially pathogenic Escherichia coli and K. pneumoniae, along with depletion of short chain fatty acid-producing Bacteroides species and beneficial colonizers. Integrated multi-omic analyses across the prenatal-postnatal axis indicated that the impaired establishment of gut microbiome in AD infants may, in part, be attributed to the (1) potential transmission of maternally originated Klebsiella and (2) immunomodulatory effects of a maternal-prenatal pro-inflammatory, TH2-skewed milieu during gestation. Conclusions Our study uncovers a distinct maternal-prenatal gut microbiome and systemic metabolome–immune signature that predisposes offspring to AD by disrupting early-life gut microbial establishment. These findings highlight the gestational period as a critical window for preventive strategies targeting the maternal microbiome or systemic immune-metabolic axes to mitigate allergic disease susceptibility in offspring. Trial registration This study is registered at ClinicalTrials.gov (NCT 03531658).

Genome sequencing of 1537 individuals from 139 ethnic groups reveals the genetic characteristics of understudied populations in North Asia and South America. Our analysis demonstrates that West Siberian ancestry, represented by the Kets and Nenets, contributed to the genetic ancestry of most Siberian populations. West Beringians, including the Koryaks, Inuit, and Luoravetlans, exhibit genetic adaptation to Arctic climate, including medically relevant variants. In South America, early migrants split into four groups—Amazonians, Andeans, Chaco Amerindians, and Patagonians—~13,900 years ago. Their longest migration led to population decline, whereas settlement in South America’s diverse environments caused instant spatial isolation, reducing genetic and immunogenic diversity. These findings highlight how population history and environmental pressures shaped the genetic architecture of human populations across North Asia and South America.

Air quality monitoring typically overlooks the biological composition of airborne particles, despite its relevance to human health. This study evaluated the feasibility of using filters from high-volume air samplers, widely employed in air quality networks, to analyze bioaerosol content through shotgun metagenomic sequencing. We developed a DNA extraction method for ultra-low biomass samples and assessed the impact of sampling duration, particle size selection, and filter material on microbial diversity. Our findings show that prolonged continuous sampling reduces species detection, while larger particle size selectors capture a broader range of microbial content, particularly fungi. Comparisons with a dedicated bioaerosol sampler confirmed that these filters can yield comparable results. This work demonstrates that existing air quality infrastructure can be leveraged for airborne microbiome monitoring, offering a practical and cost-effective approach to integrate biological data into routine assessments and support a more comprehensive understanding of air quality and its implications for public health.

Amid escalating concerns regarding climate change and air pollution, the intricate interplay between climate dynamics and air microbiomes remains inadequately understood. Our research team is dedicated to an in-depth exploration of bioaerosol dynamics through metagenomic analysis. This will establish linkages between resultant environmental microbiomes and a spectrum of physico-chemical factors. We will further evaluate potential implications of climate driven bioaerosol dynamics on human health. Consequently, our research initiative entails a comprehensive analysis of bioaerosol dynamics across distinct climate regimes, encompassing alpine, temperate, and tropical environments. Using high-volumetric air sampling technologies, we have conducted environmental time series that offer high temporal and taxonomic resolution. In an interdisciplinary approach that integrates expertise from aerobiology, medicine, atmospheric physics, and climate modelling, we aim at assessing the impact of raising global temperatures on atmospheric bioaerosols and the global dispersal of airborne microorganisms. Our bioaerosol detection methodologies can be applied to both, historical and contemporary air samples, enabling to examine the bioaerosol dynamics preceding the current and most acute climate crisis. By integrating biological, chemical, and physical measurements collected from pristine alpine and metropolitan areas from temperate and tropical settings, we investigate the potential interconnections between climate-driven alterations in airborne microbial dynamics and their consequential effects on human and ecosystem health.

Centromeres are essential for chromosome function, yet their role in shaping genome evolution in polyploid plants remains poorly understood. Allopolyploidy, where post-hybridization genome doubling merges parental genomes that may differ markedly in chromosomal architecture, has the potential to increase centromeric complexity and influence genomic plasticity. We explore this possibility in carnivorous Caryophyllales, a morphologically and chromosomally diverse plant lineage encompassing sundews, Venus flytraps, and Nepenthes pitcher plants. Focusing on sundews ( Drosera ), we generated chromosome-scale assemblies of holocentric D. regia and monocentric D. capensis , which share an allohexaploid origin but have diverged dramatically in genome structure. D. regia retains ancestral chromosomal fusions, dispersed centromeric repeats, and conserved synteny, whereas D. capensis exhibits extensive chromosomal reorganization and regionally localized centromeres after a lineage-specific genome duplication. Phylogenomic evidence traces D. regia to an ancient hybridization between sundew- and Venus flytrap-like ancestors, setting it apart within its infrageneric context. Genus-wide satellite DNA repeat profiling reveals rapid turnover and species-level variation in centromere organization. Together, these results establish sundews as a natural system for investigating how centromere dynamics interact with recurrent polyploidization and episodes of ecological innovation to shape genomic resilience. ### Competing Interest Statement The authors have declared no competing interest.

Temporal Dynamics of Atmospheric Microbial Communities in the Alps: Insights from 11-Years of High-Altitude SamplingMarie Labat Saint Vincent1; Patrik Winiger2; Julian Weng2; Stephan C. Schuster3; Christoph Hueglin4; Sophie Darfeuil1; Pauline Bros-Rolere1; Patrick Ginot1; Claudia Mohr2,5; Jean-Luc Jaffrezo1; Imad El-Haddad2; Aurélien Dommergue1; Catherine Larose11: Institut des Géosciences de l’Environnement (IGE) CNRS, UGA, IRD, INRAE, Grenoble INP, 38058, Grenoble CEDEX, France2 : PSI Center for Energy and Environmental Sciences (PSI-CEES), Paul Scherrer Institute, Villigen, 5232, Switzerland3 : Singapore Centre for Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University Singapore, Singapore, Singapore4 : Swiss Federal Laboratories for Materials Science and Technology (EMPA), Dübendorf, 8600, Switzerland5 : Department of Environmental Systems Science, ETH Zurich, 8092 Zürich, Switzerland Atmospheric microbial communities play a significant role in biogeochemical cycles and serve as a key source of microorganisms deposited onto glacial surfaces, where they may be preserved for millennia. Understanding the dynamics of these communities and their responses to environmental factors is critical for assessing their transfer and preservation in glacial archives. In this study, we leverage a unique dataset collected by the Swiss National Air Pollution Monitoring Network (NABEL), consisting of 11 years (2010–2021) of atmospheric particulate samples from Jungfraujoch (3500m a.s.l., Switzerland). This sampling site provides a rare opportunity to unravel atmospheric microbial community dynamics at high altitude as well as providing information on the pool of microorganisms that can potentially be deposited onto glaciers in the Alps.DNA extraction and quantitative PCR (qPCR) were performed on atmospheric filters collected every four days (>1000 samples) to quantify microbial abundance. These data allow us to investigate the temporal trends in abundance in the Alpine atmosphere over more than a decade, highlighting seasonal variations over time. Additionally, correlations with geo-physico-chemical environmental parameters, like temperature, pollution events, and atmospheric composition, were carried out to identify key factors driving these dynamics.This time series represents one of the most comprehensive temporal datasets of atmospheric microbial dynamics at high altitude available. In addition to providing a unique opportunity to characterize the drivers of microbial communities in the atmosphere over longer time scales, this data also represents an important step towards understanding the processes governing microbial deposition and preservation in Alpine ice. This work lays the foundation to the broader goal of validating ice cores as reliable archives of past atmospheric microbial diversity and environmental conditions.

AbstractBlood meals are crucial for the reproductive cycle ofAedes aegyptiand represent the means by which arboviruses are transmitted to its hematophagy hosts. It also has been postulated that feeding on blood may modulate the mosquito microbiome, but the compositional shifts in microbial diversity and function remain elusive. In this paper, we analyzed the modulation of the midgut microbiome in 60 females ofAedes aegyptithroughout the digestive period, 12, 24, and 48 hours after blood or sugar meals using whole-genome shotgun sequencing. Microbial transstadial transmission between larvae and adults was also assessed. This approach provided a high coverage of the midgut metagenome, allowing microbial taxonomic assignments at the species level and gene-based functional profiling. Females at later hours post-feeding and larvae display low microbiome diversities and little evidence of transstadial transmission. However, a striking proliferation of Enterobacterales was observed during early hours of digestion in blood-fed mosquitoes. The compositional shift was concomitant with a predicted functional change in genes associated with carbohydrate and protein metabolism. The observed shifts in blood-fed females’ midguts are restored to a sugar-fed-like microbial profile after 48h, when blood digestion is completed. Conversely, as in all blood-fed females, a high abundance of the opportunistic human pathogenElizabethkingia anophelis(Flavobacteriales) takes place in this post-digestion stage. This bacterial species has also been described as a symbiont of mosquitoes of the genusAnopheles(Culicidae). This work is the first report of the adaptation of the midgut microbiomeof A. aegyptito a digestive role after a blood meal, at the expense of the proliferation of potential symbionts.Significance statementThe findings in this paper can contribute to a better understanding of the dynamics of the mosquito microbiome during digestion and its potential implications for host physiology and metabolism, also informing the future development of sustainable methods for insect-borne diseases control based on microbial components that might influence vectorial capacity and pathogen transmission byA. aegypti.

Research on triethylene glycol (TEG) use to disinfect airborne microorganisms have been conducted in non-realistic chamber settings. This study assesses how air temperature, humidity, HVAC settings, and filtration impact TEG's effectiveness in deactivating a common SARS-CoV-2 substitute, MS2 bacteriophage, in a simulated non-occupied office-sized chamber. The chamber was served by a dedicated HVAC system operating at 22.0, 23.5 and 25.0oC, at 40, 55 and 70% relative humidity, at 0, 3 and 6 air change per hour (ACH) recirculation, at 0.8, 2.5 and 5.0 ACH outdoor ventilation and at no, MERV8 and MERV14 filtration status. Airborne MS2 log10 reductions in the presence of TEG increased linearly over time and we noted a higher MS2 inactivation rate with higher TEG concentration. The estimated TEG concentration needed for a one-log inactivation of the MS2 within an hour was 0.44mg/m3. The efficacy of TEG declined with the increase in temperature from 22.0 to 25.0oC, peaked at 55% RH, increased with higher recirculation rates but decreased with increasing ventilation rates and higher efficiency filters. The results of our study suggest that the optimum environmental and building conditions for TEG performance is at 22.0 or 23.5oC air temperature, 55% relative humidity, 0.8 ACH ventilation rate and 6 ACH recirculation rate. By conducting experiments in simulated office conditions, this study closes significant knowledge gaps in TEG performance application.

Blood-feeding is crucial for the reproductive cycle of the mosquito Aedes aegypti, as well as for the transmission of arboviruses to hosts. It is postulated that blood meals may influence the mosquito microbiome but shifts in microbial diversity and function during digestion remain elusive. We used whole-genome shotgun metagenomics to monitor the midgut microbiome in 60 individual females of A. aegypti throughout digestion, after 12, 24, and 48 h following blood or sugar meals. Additionally, ten individual larvae were sequenced, showing microbiomes dominated by Microbacterium sp. The high metagenomic coverage allowed for microbial assignments at the species taxonomic level, also providing functional profiling. Females in the post-digestive period and larvae displayed low microbiome diversities. A striking proliferation of Enterobacterales was observed during digestion in blood-fed mosquitoes. The compositional shift was concomitant with enrichment in genes associated with carbohydrate and protein metabolism, as well as virulence factors for antimicrobial resistance and scavenging. The bacterium Elizabethkingia anophelis (Flavobacteriales), a known human pathogen, was the dominant species at the end of blood digestion. Phylogenomics suggests that its association with hematophagous mosquitoes occurred several times. We consider evidence of mutually beneficial host-microbe interactions raised from this association, potentially pivotal for the mosquito's resistance to arbovirus infection. After digestion, the observed shifts in blood-fed females' midguts shifted to a sugar-fed-like microbial profile. This study provides insights into how the microbiome of A. aegypti is modulated to fulfil digestive roles following blood meals, emphasizing proliferation of potential symbionts in response to the dynamic midgut environment.

Air pollution is a key global environmental problem raising human health concern. It is essential to comprehensively assess the long-term characteristics of air pollution and the resultant health impacts. We first assessed the global trends of fine particulate matter (PM2.5) during 1980-2020 using a monthly global PM2.5 reanalysis dataset, and evaluated their association with three types of climate variability including El Niño-Southern Oscillation, Indian Ocean Dipole and North Atlantic Oscillation. We then estimated PM2.5-attributable premature deaths using integrated exposure-response functions. Results show a significant increasing trend of ambient PM2.5 during 1980-2020 due to increases in anthropogenic emissions. Ambient PM2.5 caused a total of ∼ 135 million premature deaths globally during the four decades. Occurrence of air pollution episodes was strongly associated with climate variability, which were associated with up to 14 % increase in annual global PM2.5-attributable premature deaths.

Background Heat-inactivated probiotics (HPs) may provide an effective alternative to live probiotics (P) by avoiding their risks (eg, probiotic sepsis) while retaining the benefits. We assessed the safety and efficacy of a HP in very preterm (VP: gestation <32 weeks) infants. Methods VP infants were randomly allocated to receive a HP or P mixture ( Bifidobacterium breve M-16V, Bifidobacterium longum subsp. infantis M-63, Bifidobacterium longum subsp. longum BB536, total 3×10 9 CFU/day) assuring blinding. Primary outcome was faecal calprotectin (FCP) levels were compared after 3 weeks of supplementation. Secondary outcomes included faecal microbiota and short chain fatty acid (SCFA) levels. Results 86 VP infants were randomised to HP or P group (n=43 each). Total FCP and SCFA were comparable between HP and P groups within 7 days (T1) and between day 21 and 28 (T2) after supplementation. At T2, median (range) FCP was 75 (8–563) in the HP group and 80 (21–277) in the P group (p=0.71). Propionate was significantly raised in both groups, while butyrate was significantly raised in the HP group (all p<0.01). Bacterial richness and diversity increased but was comparable between HP and P (p>0.05). Beta diversity showed similar community structures in both groups (all p>0.05). Changes in faecal Actinobacteria, Bacteroidetes and Bifidobacteriacae levels were comparable in both groups at T1 and T2. There was no probiotic sepsis. Conclusions HP was safe and showed no significant difference in FCP as compared with a live probiotic. Adequately powered trials are needed to assess the effects of HP on clinically significant outcomes in preterm infants. Trial registration number ACTRN12618000489291.

This study investigates the diel cycle of airborne microorganisms indoors and its role as a proxy for indoor air quality. Using metagenomic analysis, 124 air samples were collected and analyzed on phylum, genus, and species level classifications. The study includes samples from two offices (Office 1 and Office 2) and an outdoor setting, each taken over six days and nights. Results show a clear day-night cycle for indoor bioaerosols in Office 1, distinct from the outdoor environment, with human-associated taxa dominating during the day. Office 2, considered polluted with mold, displays a divergent taxonomic profile lacking bacterial taxa. The study highlights the influence of mechanical ventilation on indoor bioaerosol dynamics, with night-time infiltration of outdoor air leading to the equilibration of indoor and outdoor air microbiomes. Furthermore, the study examines the effect of outdoor temperature on indoor air microbiome composition, observing disruptions in the outdoor diel cycle during a period of unusually low temperatures. Finally, the efficacy of mold removal and sanitation efforts is confirmed through follow-up air sampling, indicating significant reductions in Aspergillus versicolor and airborne fungal copy numbers. This comprehensive metagenomic survey sheds light on the role of indoor bioaerosol dynamics in instigating health related issues. Inclusion of such highly-resolved bioaerosol monitoring effort into the currently established air quality standards shall provide invaluable insights on improving indoor air quality through ventilation and sanitation efforts.

Blood meals are crucial for the reproductive cycle of Aedes aegypti and represent the means by which arboviruses are transmitted to its hematophagy hosts. It also has been postulated that feeding on blood may modulate the mosquito microbiome, but the compositional shifts in microbial diversity and function remain elusive. In this paper, we analyzed the modulation of the midgut microbiome in 60 females of Aedes aegypti throughout the digestive period, 12, 24, and 48 hours after blood or sugar meals using whole-genome shotgun sequencing. Microbial transstadial transmission between larvae and adults was also assessed. This approach provided a high coverage of the midgut metagenome, allowing microbial taxonomic assignments at the species level and gene-based functional profiling. Females at later hours post-feeding and larvae display low microbiome diversities and little evidence of transstadial transmission. However, a striking proliferation of Enterobacterales was observed during early hours of digestion in blood-fed mosquitoes. The compositional shift was concomitant with a predicted functional change in genes associated with carbohydrate and protein metabolism. The observed shifts in blood-fed females’ midguts are restored to a sugar-fed-like microbial profile after 48h, when blood digestion is completed. Conversely, as in all blood-fed females, a high abundance of the opportunistic human pathogen Elizabethkingia anophelis (Flavobacteriales) takes place in this post-digestion stage. This bacterial species has also been described as a symbiont of mosquitoes of the genus Anopheles (Culicidae). This work is the first report of the adaptation of the midgut microbiome of A. aegypti to a digestive role after a blood meal, at the expense of the proliferation of potential symbionts. Significance statement The findings in this paper can contribute to a better understanding of the dynamics of the mosquito microbiome during digestion and its potential implications for host physiology and metabolism, also informing the future development of sustainable methods for insect-borne diseases control based on microbial components that might influence vectorial capacity and pathogen transmission by A. aegypti . ### Competing Interest Statement The authors have declared no competing interest.

BACKGROUND:Sensitisation to Aspergillus fumigatus is linked to worse outcomes in patients with COPD; however, its prevalence and clinical implications in domestic (residential) settings remains unknown. METHODS:Individuals with COPD (n=43) recruited in Singapore had their residences prospectively sampled and assessed by shotgun metagenomic sequencing including indoor air, outdoor air and touch surfaces (a total of 126 specimens). The abundance of environmental A. fumigatus and the occurrence of A. fumigatus (Asp f) allergens in the environment were determined and immunological responses to A. fumigatus allergens determined in association with clinical outcomes including exacerbation frequency. Findings were validated in 12 individuals (31 specimens) with COPD in Vancouver, Canada, a climatically different region. RESULTS:157 metagenomes from 43 homes were assessed. 11 and nine separate Aspergillus spp. were identified in Singapore and Vancouver, respectively. Despite climatic, temperature and humidity variation, A. fumigatus was detectable in the environment from both locations. The relative abundance of environmental A. fumigatus was significantly associated with exacerbation frequency in both Singapore (r=0.27, p=0.003) and Vancouver (r=0.49, p=0.01) and individuals with higher Asp f 3 sensitisation responses lived in homes with a greater abundance of environmental Asp f 3 allergens (p=0.037). Patients exposed and sensitised to Asp f 3 allergens demonstrated a higher rate of COPD exacerbations at 1-year follow-up (p=0.021). CONCLUSION:Environmental A. fumigatus exposure in the home environment including air and surfaces with resulting sensitisation carries pathogenic potential in individuals with COPD. Targeting domestic A. fumigatus abundance may reduce COPD exacerbations.

Background: Airway mycobiomes in COPD demonstrating increased Aspergillus, Curvularia and Penicillium associated with poorer clinical outcomes, however, their relationship to environmental exposure in the home remains unexplored. Methods: Patients with stable COPD (n=43) and healthy participants (n=28) were prospectively recruited and underwent clinical data collation and home studies including deep shotgun metagenomic assessment of host (sputum), indoor air (bedroom), outdoor air (balcony) and surface dust (fan or air-conditioner filter) (4 metagenomes per home; Total 284 metagenomes). Results: Shotgun metagenomics reveals increased Aspergillus fumigatus, Pseudomonas alcaligenes and Brevibacterium luteolum in indoor air (bedroom) and Malassezia restrica and Aspergillus spp. in surface dust and outdoor air (balcony) in the homes of individuals with COPD. Relative abundance of indoor air Aspergillus fumigatus positively correlates with exacerbation frequency in COPD (r=0.4, p=0.009) however no differences were observed in symptom burden or lung function. Conclusion: Aspergillus spp., present at increased levels in the home environment is associated to COPD exacerbations. Environmental exposures in the home represent a source of Aspergillus-related outcomes in COPD. Funding: Singapore Ministry of Health's NMRC under its Clinician Scientist Award (CSA) (MOH-000710) (S.H.C) & Singapore Ministry of Education under its AcRF Tier 1 Grant (RT1/22) (S.H.C).