Naomichi Yamamoto

Fungi are ubiquitous in outdoor air, and their concentration, aerodynamic diameters and taxonomic composition have potentially important implications for human health. Although exposure to fungal allergens is considered a strong risk factor for asthma prevalence and severity, limitations in tracking fungal diversity in air have thus far prevented a clear understanding of their human pathogenic properties. This study used a cascade impactor for sampling, and quantitative real-time PCR plus 454 py

Adequate ventilation or air exchange rate (AER) for an indoor environment is important for human health and comfort, and relevant to building design and energy conservation and efficiency considerations. However, residential AER data, especially measured by more accurate non-toxic tracer gas methodologies, are at present quite limited worldwide, and are insufficient to represent the variations across regions and seasons within and between homes, including apartments and condominiums in more dens

This study quantifies the influence of ventilation and indoor emissions on concentrations and particle sizes of airborne indoor allergenic fungal taxa and further examines geographical variability, each of which may affect personal exposures to allergenic fungi. Quantitative PCR and multiplexed DNA sequencing were employed to count and identify allergenic fungal aerosol particles indoors and outdoors in seven school classrooms in four different countries. Quantitative diversity analysis was comb

Fungi are ubiquitous in indoor and outdoor environments, and many fungi are known to cause allergic reactions and exacerbate asthma attacks. This study established--by modifying an existing--a wipe sampling method to collect fungi in floor dust followed by real-time quantitative PCR (qPCR)-based detection methodologies. Results from this combined laboratory and field assessment suggested the methodology's potential to inform larger human exposure studies for fungal pathogens and allergens in hou

Indoor visible mold growths are known to be associated with allergies and respiratory illnesses. However, a question remains of their compositions and diversities. Using swab sampling and high-throughput DNA sequencing, this study analyzed taxonomic compositions and diversities of fungi on indoor surfaces laden with visible mold growths in residential apartments in South Korea. The sequencing results showed low species diversities with Shannon indices ranging from 0.14 to 2.29 (mean = 1.11). Sev

Next-generation DNA sequencing has enabled a rapid expansion in the size of molecular fungal ecology studies employing the nuclear internal transcribed spacer (ITS) region. Many sequence-processing pipelines and protocols require sequence clustering to generate operational taxonomic units (OTUs) based on sequence similarity as a step to reduce total data quantity and complexity prior to taxonomic assignment. However, the consequences of ITS sequence clustering in regard to sample taxonomic cover

Japanese cedar pollinosis (JCP) is an important illness caused by the inhalation of airborne allergenic cedar pollens, which are dispersed in the early spring throughout the Japanese islands. However, associations between pollen exposures and the prevalence or severity of allergic symptoms are largely unknown, due to a lack of understanding regarding personal pollen exposures in relation to indoor and outdoor concentrations. This study aims to examine the relationships among indoor, outdoor, and

We compared the status of carbonaceous aerosols in Tokyo before and after the implementation of a diesel vehicle regulation intended to reduce the quantity of particulate carbon from diesel engines in one of the largest scale ever attempts at vehicle exhaust control. Radiocarbon (14C) in elemental carbon (EC) and total carbon (TC) were analyzed to identify fossil fuel carbonaceous particles emitted from diesel-powered vehicles. One-sided paired-month t-tests showed no distinct difference in the