[ { "id": "authors:brdw0-qey65", "collection": "authors", "collection_id": "brdw0-qey65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200909-135124154", "type": "article", "title": "Coronavirus Disease 2019 Patients in Earlier Stages Exhaled Millions of Severe Acute Respiratory Syndrome Coronavirus 2 Per Hour", "author": [ { "family_name": "Ma", "given_name": "Jianxin", "clpid": "Ma-Jianxin" }, { "family_name": "Qi", "given_name": "Xiao", "clpid": "Qi-Xiao" }, { "family_name": "Chen", "given_name": "Haoxuan", "orcid": "0000-0001-8398-9093", "clpid": "Chen-Haoxuan" }, { "family_name": "Li", "given_name": "Xinyue", "orcid": "0000-0002-0822-4960", "clpid": "Li-Xinyue" }, { "family_name": "Zhang", "given_name": "Zheng", "clpid": "Zhang-Zheng" }, { "family_name": "Wang", "given_name": "Haibin", "clpid": "Wang-Haibin" }, { "family_name": "Sun", "given_name": "Lingli", "clpid": "Sun-Lingli" }, { "family_name": "Zhang", "given_name": "Lu", "clpid": "Zhang-Lu" }, { "family_name": "Guo", "given_name": "Jiazhen", "clpid": "Guo-Jiazhen" }, { "family_name": "Morawska", "given_name": "Lidia", "orcid": "0000-0002-0594-9683", "clpid": "Morawska-Lidia" }, { "family_name": "Grinshpun", "given_name": "Sergey A.", "orcid": "0000-0003-4339-927X", "clpid": "Grinshpun-Sergey-A" }, { "family_name": "Biswas", "given_name": "Pratim", "orcid": "0000-0003-1104-3738", "clpid": "Biswas-Pratim" }, { "family_name": "Flagan", "given_name": "Richard C.", "orcid": "0000-0001-5690-770X", "clpid": "Flagan-R-C" }, { "family_name": "Yao", "given_name": "Maosheng", "orcid": "0000-0002-1442-8054", "clpid": "Yao-Maosheng" } ], "abstract": "Coronavirus disease 2019 (COVID-19) patients exhaled millions of severe acute respiratory syndrome coronavirus 2 RNA copies per hour, which plays an important role in COVID-19 transmission. Exhaled breath had a higher positive rate (26.9%, n = 52) than surface (5.4%, n = 242) and air (3.8%, n = 26) samples.", "doi": "10.1093/cid/ciaa1283", "pmcid": "PMC7499537", "issn": "1058-4838", "publisher": "Oxford University Press", "publication": "Clinical Infectious Diseases", "publication_date": "2021-05-15", "series_number": "10", "volume": "72", "issue": "10", "pages": "e652-e654" }, { "id": "authors:npa4g-rjj03", "collection": "authors", "collection_id": "npa4g-rjj03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201027-093242333", "type": "article", "title": "Breath-, air- and surface-borne SARS-CoV-2 in hospitals", "author": [ { "family_name": "Zhou", "given_name": "Lian", "clpid": "Zhou-Lian" }, { "family_name": "Yao", "given_name": "Maosheng", "orcid": "0000-0002-1442-8054", "clpid": "Yao-Maosheng" }, { "family_name": "Zhang", "given_name": "Xiang", "orcid": "0000-0003-4462-3798", "clpid": "Zhang-Xiang" }, { "family_name": "Hu", "given_name": "Bicheng", "clpid": "Hu-Bicheng" }, { "family_name": "Li", "given_name": "Xinyue", "orcid": "0000-0002-0822-4960", "clpid": "Li-Xinyue" }, { "family_name": "Chen", "given_name": "Haoxuan", "orcid": "0000-0001-8398-9093", "clpid": "Chen-Haoxuan" }, { "family_name": "Zhang", "given_name": "Lu", "clpid": "Zhang-Lu" }, { "family_name": "Liu", "given_name": "Yun", "clpid": "Liu-Yun" }, { "family_name": "Du", "given_name": "Meng", "clpid": "Du-Meng" }, { "family_name": "Sun", "given_name": "Bochao", "clpid": "Sun-Bochao" }, { "family_name": "Jiang", "given_name": "Yunyu", "clpid": "Jiang-Yunyu" }, { "family_name": "Zhou", "given_name": "Kai", "clpid": "Zhou-Kai" }, { "family_name": "Hong", "given_name": "Jie", "clpid": "Hong-Jie" }, { "family_name": "Yu", "given_name": "Na", "clpid": "Yu-Na" }, { "family_name": "Ding", "given_name": "Zhen", "clpid": "Ding-Zhen" }, { "family_name": "Xu", "given_name": "Yan", "clpid": "Xu-Yan" }, { "family_name": "Hu", "given_name": "Min", "clpid": "Hu-Min" }, { "family_name": "Morawska", "given_name": "Lidia", "orcid": "0000-0002-0594-9683", "clpid": "Morawska-Lidia" }, { "family_name": "Grinshpun", "given_name": "Sergey A.", "orcid": "0000-0003-4339-927X", "clpid": "Grinshpun-Sergey-A" }, { "family_name": "Biswas", "given_name": "Pratim", "orcid": "0000-0003-1104-3738", "clpid": "Biswas-Pratim" }, { "family_name": "Flagan", "given_name": "Richard C.", "orcid": "0000-0001-5690-770X", "clpid": "Flagan-R-C" }, { "family_name": "Zhu", "given_name": "Baoli", "clpid": "Zhu-Baoli" }, { "family_name": "Liu", "given_name": "Wenqing", "clpid": "Liu-Wenqing" }, { "family_name": "Zhang", "given_name": "Yuanhang", "clpid": "Zhang-Yuanhang" } ], "abstract": "The COVID-19 pandemic has brought an unprecedented crisis to the global health sector. When discharging COVID-19 patients in accordance with throat or nasal swab protocols using RT-PCR, the potential risk of reintroducing the infection source to humans and the environment must be resolved. Here, 14 patients including 10 COVID-19 subjects were recruited; exhaled breath condensate (EBC), air samples and surface swabs were collected and analyzed for SARS-CoV-2 using reverse transcription-polymerase chain reaction (RT-PCR) in four hospitals with applied natural ventilation and disinfection practices in Wuhan. Here we discovered that 22.2% of COVID-19 patients (n = 9), who were ready for hospital discharge based on current guidelines, had SARS-CoV-2 in their exhaled breath (~10\u2075 RNA copies/m\u00b3). Although fewer surface swabs (3.1%, n = 318) tested positive, medical equipment such as face shield frequently contacted/used by healthcare workers and the work shift floor were contaminated by SARS-CoV-2 (3\u20138 viruses/cm\u00b2). Three of the air samples (n = 44) including those collected using a robot-assisted sampler were detected positive by a digital PCR with a concentration level of 9\u2013219 viruses/m\u00b3. RT-PCR diagnosis using throat swab specimens had a failure rate of more than 22% in safely discharging COVID-19 patients who were otherwise still exhaling the SARS-CoV-2 by a rate of estimated ~1400 RNA copies per minute into the air. Direct surface contact might not represent a major transmission route, and lower positive rate of air sample (6.8%) was likely due to natural ventilation (1.6\u20133.3 m/s) and regular disinfection practices. While there is a critical need for strengthening hospital discharge standards in preventing re-emergence of COVID-19 spread, use of breath sample as a supplement specimen could further guard the hospital discharge to ensure the safety of the public and minimize the pandemic re-emergence risk.", "doi": "10.1016/j.jaerosci.2020.105693", "pmcid": "PMC7557302", "issn": "0021-8502", "publisher": "Elsevier", "publication": "Journal of Aerosol Science", "publication_date": "2021-02", "volume": "152", "pages": "Art. No. 105693" }, { "id": "authors:52ynf-ke426", "collection": "authors", "collection_id": "52ynf-ke426", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150805-104915988", "type": "article", "title": "The particle trap impactor", "author": [ { "family_name": "Biswas", "given_name": "Pratim", "orcid": "0000-0003-1104-3738", "clpid": "Biswas-Pratim" }, { "family_name": "Flagan", "given_name": "Richard C.", "orcid": "0000-0001-5690-770X", "clpid": "Flagan-R-C" } ], "abstract": "The performance of virtual impactors with no flow through the impaction orifice was examined experimentally. An open cavity particle trap with an orifice diameter 1.9 times the jet diameter yielded sharp size cuts with a maximum collection efficiency of about 90 percent, with no degradation of performance at very high Stokes number. The suitability of the particle trap for operation with jet velocities up to the sonic limit and for use at elevated temperature was also demonstrated. In extended duration operation, the collection efficiency did not decrease until the trap was nearly filled.", "doi": "10.1016/0021-8502(88)90260-1", "issn": "0021-8502", "publisher": "Elsevier", "publication": "Journal of Aerosol Science", "publication_date": "1988-02", "series_number": "1", "volume": "19", "issue": "1", "pages": "113-121" }, { "id": "authors:0b7hx-tfy98", "collection": "authors", "collection_id": "0b7hx-tfy98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150630-170058965", "type": "article", "title": "Distortion of Size Distributions by Condensation and Evaporation in Aerosol Instruments", "author": [ { "family_name": "Biswas", "given_name": "Pratim", "orcid": "0000-0003-1104-3738", "clpid": "Biswas-Pratim" }, { "family_name": "Jones", "given_name": "Carol L.", "clpid": "Jones-Carol-L" }, { "family_name": "Flagan", "given_name": "Richard C.", "orcid": "0000-0001-5690-770X", "clpid": "Flagan-R-C" } ], "abstract": "Aerosols that contain volatile species or condensable vapors may be altered by changes in temperature, pressure, and vapor concentration. When such changes occur within aerosol sampling instruments, the measured size distribution can be distorted significantly. The distortion of particle size distributions in a number of commonly used aerosol instruments, including cascade impactors, both conventional and low pressure instruments, and optical particle counters, is explored both theoretically and experimentally in this paper. Ammonium sulfate aerosols in humid atmospheres have been used to test the instruments. In a low pressure impactor in which the pressure is intentionally reduced to facilitate the collection of small particles, a water containing particle may shrink due to evaporation as the pressure is reduced. However, if the sample flow is also accelerated to high velocities, aerodynamic cooling can lead to condensation of water vapor and particle growth. Either of these competing effects may lead to erroneous estimates of the particle size distribution. Optical particle counters generally use a recirculated sheath airflow. Pumps and electrical dissipation heat this air, leading to a temperature increase that shifts the vapor equilibrium, causing a decrease in particle size due to evaporation. Modifications\nhave been made to avoid this distortion in measured size distributions.", "doi": "10.1080/02786828708959161", "issn": "0278-6826", "publisher": "American Association for Aerosol Research", "publication": "Aerosol Science and Technology", "publication_date": "1987-02", "series_number": "2", "volume": "7", "issue": "2", "pages": "231-246" }, { "id": "authors:8vy5q-rgk39", "collection": "authors", "collection_id": "8vy5q-rgk39", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150630-105755532", "type": "article", "title": "High-Velocity Inertial Impactors", "author": [ { "family_name": "Biswas", "given_name": "Pratim", "clpid": "Biswas-Pratim" }, { "family_name": "Flagan", "given_name": "Richard C.", "orcid": "0000-0001-5690-770X", "clpid": "Flagan-R-C" } ], "abstract": "Cascade impactors with large pressure drops across individual stages are useful for classifying submicron aerosols even though the flow becomes compressible when the ratio of the downstream to upstream stagnation pressure falls below r = 0.95 and sonic when r < 0.53 (for air). The variation of collection efficiency with pressure ratio is examined experimentally. The cutoff Stokes number does not exhibit significant dependence on the pressure ratio in the range from r = 0.97 (incompressible flow) to r = 0.19 (choked flow). The impactor stage pressure ratio may be estimated by modeling the stage as a nonideal, compressible flow nozzle with a discharge coefficient which is well correlated with the jet Reynolds number divided by the nozzle throat aspect ratio. Predictions of the variation of the cutoff diameter with flow rate, temperature, and inlet pressure are presented for impactors with high Mach number jets.", "doi": "10.1021/es00126a009", "issn": "0013-936X", "publisher": "American Chemical Society", "publication": "Environmental Science and Technology", "publication_date": "1984-08", "series_number": "8", "volume": "18", "issue": "8", "pages": "611-616" } ]