Characterise sources for exposure assessment of chemicals in indoor environment

It is well known that the airflow is instrumental in the transmission of airborne infectious diseases in indoor environments. The airflow pattern in indoor environment is affected by the ventilation airflow, thermal plume around human bodies, human respiration, human motion and other activities. In this study, the CFD approach was used to simulate airflow field and particle transport in a room to provide exposure assessment for a heated breathing manikin with and without rotational motion. The simulation results indicated that the rotation of the manikin significantly impacts the thermal plume of the body and the associated transport of particulates.

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An immunoassay for the measurement of (1→3)-β-D-glucans in the indoor environment

Mediators of Inflammation ◽

10.1080/09629359791578 ◽

1997 ◽

Vol 6 (4) ◽

pp. 257-262 ◽

Cited By ~ 9

Author(s):

Jeroen Douwes ◽

Gert Doekes ◽

Roy Montijn ◽

Dick Heederik ◽

Bert Brunekreef

Keyword(s):

Enzyme Immunoassay ◽

Exposure Assessment ◽

Calibration Curve ◽

Bovine Serum ◽

Indoor Environment ◽

Weight Basis ◽

Inhibition Curve

An inhibition enzyme immunoassay was developed for quantitation of (1→3)-β-D-glucans in the indoor environment. Immunospecific rabbit antibodies were produced by immunization with bovine serum albuminconjugated laminarin.The laminarin calibration curve ranged from 40 to 3000 ng/ml.Another (1→3)-β-D-glucan (curdlan) showed a similar inhibition curve, but was less reactive on a weight basis. Pustulan, presumed to be (1→3)-β-D-glucan, also showed immunoreactivity in the assay. Control experiments indicated that this was due to (1→3)-β-D-glucan structures. Other non-(1→3)-β-D-glucan polysaccharides did not react. (1→3)-β-Dglucan was detectable in dust from a variety of occupational and environmental settings. We conclude that the new assay offers a useful method for indoor (1→3)-β-Dglucan exposure assessment.

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Exposure assessment for airborne transmission of SARS-CoV-2 via breathing, speaking, coughing and sneezing

10.1101/2020.07.02.20144832 ◽

2020 ◽

Cited By ~ 2

Author(s):

Jack Schijven ◽

Lucie C. Vermeulen ◽

Arno Swart ◽

Adam Meijer ◽

Erwin Duizer ◽

...

Keyword(s):

Exposure Assessment ◽

Dose Response ◽

Indoor Environment ◽

Throat Swab ◽

Assessment Model ◽

Virus Concentration ◽

Infected Person ◽

Airborne Transmission ◽

Virus Particles ◽

Indoor Spaces

AbstractBackgroundEvidence for indoor airborne transmission of SARS-CoV-2 is accumulating. If SARS-CoV-2 also spreads via aerosols, this has implications for measures taken to limit transmission.ObjectivesThe aim of this study is to assess exposure to airborne SARS-CoV-2 particles from breathing, speaking, coughing and sneezing in an indoor environment.MethodsAn exposure assessment model was developed to estimate numbers of SARS-CoV-2 particles in aerosol droplets, expelled during breathing, speaking, coughing and sneezing by an infected person in an unventilated indoor environment, and subsequent inhalation by one or more persons. Scenarios encompass a range of virus concentrations, room sizes and exposure times.ResultsThe calculated total volume of expelled aerosol droplets was highest for a sneeze, followed by a cough and speaking for 20 minutes, and lastly breathing for 20 minutes. A few to as much as tens of millions of virus particles were expelled. Exposure probability strongly depends on the viral concentration in mucus, as well as on the scenario. Exposure probabilities were generally below 1% at a virus concentration in mucus below 105 per mL for all scenarios, increasing steeply at different higher concentrations. According to nose / throat swab data collected from patients, 75%, 50% and 5% of infected individuals carry an estimated number of SARS-CoV-2 per mL mucus of at least 105, 106 and 108, respectively.DiscussionExposure to SARS-CoV-2 via aerosols generated during breathing, speaking, coughing and sneezing in an unventilated indoor environment is possible. This study forms a basis to estimate probabilities of exposure to SARS-Cov-2 by airborne transmission in indoor spaces. As long as it is uncertain what fraction of the airborne virus particles is infectious and as long as a dose response relation is lacking, it is recommended to be precautious.

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Measuring “Language Access Profiles” in Deaf and Hard-of-Hearing Children With the DHH Language Exposure Assessment Tool

Journal of Speech Language and Hearing Research ◽

10.1044/2020_jslhr-20-00439 ◽

2020 ◽

pp. 1-25

Author(s):

Matthew L. Hall ◽

Stephanie De Anda

Keyword(s):

Cluster Analysis ◽

Exposure Assessment ◽

Hard Of Hearing ◽

Assessment Tool ◽

Communication Mode ◽

Developmental Potential ◽

Language Access ◽

Retest Reliability ◽

Language Exposure ◽

Test Retest Reliability

Purpose The purposes of this study were (a) to introduce “language access profiles” as a viable alternative construct to “communication mode” for describing experience with language input during early childhood for deaf and hard-of-hearing (DHH) children; (b) to describe the development of a new tool for measuring DHH children's language access profiles during infancy and toddlerhood; and (c) to evaluate the novelty, reliability, and validity of this tool. Method We adapted an existing retrospective parent report measure of early language experience (the Language Exposure Assessment Tool) to make it suitable for use with DHH populations. We administered the adapted instrument (DHH Language Exposure Assessment Tool [D-LEAT]) to the caregivers of 105 DHH children aged 12 years and younger. To measure convergent validity, we also administered another novel instrument: the Language Access Profile Tool. To measure test–retest reliability, half of the participants were interviewed again after 1 month. We identified groups of children with similar language access profiles by using hierarchical cluster analysis. Results The D-LEAT revealed DHH children's diverse experiences with access to language during infancy and toddlerhood. Cluster analysis groupings were markedly different from those derived from more traditional grouping rules (e.g., communication modes). Test–retest reliability was good, especially for the same-interviewer condition. Content, convergent, and face validity were strong. Conclusions To optimize DHH children's developmental potential, stakeholders who work at the individual and population levels would benefit from replacing communication mode with language access profiles. The D-LEAT is the first tool that aims to measure this novel construct. Despite limitations that future work aims to address, the present results demonstrate that the D-LEAT represents progress over the status quo.

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