Kelsey Babik - Academia.edu (original) (raw)

Papers by Kelsey Babik

Johns Hopkins University, Jun 9, 2021

We conducted a series of static and dynamic experiments in a fleet of passenger railcars and loco... more We conducted a series of static and dynamic experiments in a fleet of passenger railcars and locomotives for a large-scale, mass-transit company to measure the: (1) aerosol concentrations corresponding to respirable-sized/viral aerosols; (2) aerosol removal rates; and (3) air changes per hour (ACH) provided by the existing air handling systems. We evaluated the ventilation and air filtration (HVAC) systems effectiveness in a range of representative conditions to assess exposure risk. The risk of exposure to SARS-CoV-2 was assessed: (1) under standard conditions; (2) using minimum reported efficiency value (MERV) filters with increased filtration ratings; and (3) in the presence of a high-efficiency particulateabsorbing (HEPA)-scavenging system. The engineering controls evaluated included: (1) recirculated to fresh air ventilation ratio; (2) MERV filters filtration efficiency; and (3) use of an air purifier. Aerosols were generated in the 0.3-5.0 µm size range using a Collison Nebulizer. Real-time aerosol concentrations were measured at multiple locations using photodetector particle counters. The ACHs and removal rates were calculated using log-linear regression. An analysis of variance was used to compare the particle concentrations under the different experimental conditions while a multiple linear regression was used to identify which engineering control(s) impacted the particle concentrations. The risk of exposure was estimated using an approach developed by Miller et al. The recirculated to fresh air ratio had a minimal effect on particle air concentrations and on particle removal rates. The higher efficiency MERV13 filters significantly reduced particle concentrations (p<0.05) and significantly increased particle removal rates (p<0.01) compared to MERV8 filters. Compared to standard conditions, MERV13 filters reduced the exposure risk by 42%. Use of a HEPA-scavenger with a MERV13 filter causes a further reduction in risk (by 50%). The risk of exposure in the engine locomotives was much lower than in the passenger railcars due to much higher ACH values. These results show that a simple upgrade in the efficiency of the HVAC filters results in reductions of particle concentration and risk of exposure in public-transit vehicles. Widespread upgrading of HVAC filter iii efficiency in public-transit vehicles could reduce community-spread infectious respiratory diseases, protect transit workers, and slow disease spread. Primary Reader and Advisor: Gurumurthy Ramachandran Secondary Reader: Meghan Davis v DEDICATION This thesis is dedicated to my parents and Norac for planting a love of science within me at an early age. And to my teachers Mrs. Pessolano and Mrs. Ondriezek at St. Benedict School for fostering and cultivating that love and encouraging my curiosity. I also dedicate this work to little girls with big dreams who are told that they aren't good enough, smart enough, or tough enough to make the things they want happen. You are enough. vi Table of Contents ABSTRACT .

Journal of Occupational and Environmental Hygiene, 2018

In this study, we characterize the area and personal air concentrations of combustion byproducts ... more In this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21 st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.

Journal of Occupational and Environmental Hygiene

The bacterial OTUs that could not be assigned to a genus are represented as “Unclassifie... more The bacterial OTUs that could not be assigned to a genus are represented as “Unclassified” and are assigned to their family level. The grey line and arrows highlight the conversion in log2-fold change from negative to positive values. [A] Comparing Cheyenne Menthol Box (CMB) to Cheyenne Full Flavor (CFF) tobacco samples. A positive log2-fold change value denotes an OTU that is significantly higher in CFF, while a negative log2-fold change indicates an OTU that is significantly higher in CMB. [B] Comparing Swisher sweets cherry (SSC) to Swisher sweets original (SSO) tobacco samples. A positive log2-fold change value denotes an OTU that is significantly higher in SSO, while a negative log2-fold change indicates an OTU that is significantly higher in SSC. [C] Comparing Swisher sweets original (SSO) to Cheyenne Full Flavor (CFF) tobacco samples. A positive log2-fold change value denotes an OTU that is significantly higher in CFF, while a negative log2-fold change indicates an OTU that is significantly higher in SSO. [D] Comparing Cheyenne Menthol Box (CMB) to Cheyenne Full Flavor (CFF) wrapper samples. A positive log2-fold change value denotes an OTU that is significantly higher in CFF, while a negative log2-fold change indicates an OTU that is significantly higher in CMB.</p

[A] Relative abundance of top 20 bacterial genera present in tobacco and wrapper samples... more [A] Relative abundance of top 20 bacterial genera present in tobacco and wrapper samples. [B] Differential abundances of bacterial genera that were statistically significantly different (p < 0.05) between tobacco and wrapper samples. A positive log2-fold change value denotes an OTU that is significantly higher in tobacco, while a negative log2-fold change indicates an OTU that is significantly higher in wrapper. The grey line and arrows highlight the conversion in log2-fold change from negative to positive values.</p

Colors denotes the type of products: red- tobacco and blue- wrapper.</p

Violin plots showing alpha diversity (Observed number of species and Shannon Index) [A] ... more Violin plots showing alpha diversity (Observed number of species and Shannon Index) [A] across all samples using rarefied data to minimum sampling depth (red, tobacco; and blue; wrappers); and [B] by product (red, Cheyenne Full Flavor (CFF); green, Cheyenne Menthol Box (CMB); purple, Swisher sweets cherry (SSC); and blue, Swisher sweets original (SSO). [C] PCoA analysis plots of Bray-Curtis computed distances between tobacco products. Sample type is denoted by shapes: triangle, wrapper; and circle, tobacco. Ellipses are drawn at 95% confidence intervals for product brand.</p

PCoA analysis plots of Bray- Curtis computed distances between the lots of each brand an... more PCoA analysis plots of Bray- Curtis computed distances between the lots of each brand and type. Type of product is denoted by shapes: triangle- wrapper and circle- tobacco. Colors denote the different lot numbers within each brand.</p

Extent of the Marcellus Shale in Garret and Allegany Counties in Western Maryland.</p

List of Supplementary Figures and Tables. Figure S1. Rarefaction curves for each product. Figure ... more List of Supplementary Figures and Tables. Figure S1. Rarefaction curves for each product. Figure S2. PCoA analysis plots of weighted and unweighted Unifrac computed distances between cigarette products. Figure S3. Pseudomonas phylogenetic tree. Figure S4. Actinobacter phylogenetic tree. Figure S5. Stenotrophomonas phylogenetic tree. Figure S6. Anoxybacillus phylogenetic tree. Figure S7. Deinococcus phylogenetic tree. Figure S8. Vagococcus phylogenetic tree. Figure S9. Thermus phylogenetic tree. Figure S10. Proteus phylogenetic tree. Table S1. OTUs at statistically significantly different relative abundances between mentholated Camel King and non-mentholated Camel King. FC denotes fold change. (DOCX 1485 kb)

☯ These authors contributed equally to this work.

Journal of Occupational and Environmental Hygiene, 2018

Objective: Toxicology studies suggest that exposure to certain types of engineered nanomaterials ... more Objective: Toxicology studies suggest that exposure to certain types of engineered nanomaterials (ENMs) may cause adverse health effects, but little is known about the workforce in the United States that produces or uses these materials. In addition, occupational exposure control strategies in this industry are not well characterized. This study identified U.S. ENM manufacturers and users (other than carbon nanotubes and nanofibers, which have been characterized elsewhere), determined workforce size, characterized types and quantities of materials used, occupational exposure control strategies, and the feasibility of occupational ENM exposure studies. Methods: Eligible companies were identified and information was collected through phone surveys on nanomaterials produced or used, workforce size, location, work practices, and exposure control strategies. The companies were classified into groups for additional examinations. Results: Forty-nine companies producing or using ENMs in the...

Building and Environment, 2021

Abstract Household air pollution due to solid fuel (biomass) combustion is widely prevalent in ru... more Abstract Household air pollution due to solid fuel (biomass) combustion is widely prevalent in rural households in the developing world. Providing adequate ventilation can be a potential method to reduce exposures to residents. Previous cookstove studies in rural areas around the world have estimated the ventilation air changes per hour (ACH) values to be of the order of >20. These studies use a one-compartment model to estimate the ACH from the decay of the pollutant released very near to the cookstove. While the one-box compartmental model is appropriate for estimating exposures farther away from emission sources, a multi-compartment (e.g., a 2-box model) may be more appropriate for distinguishing between exposures of the cook versus other occupants in the house, as well as estimating ventilation rates in the house. In the present study, we use a two-compartment model to estimate the ACH. Field based particulate matter measurements were carried out in 40 Bangladesh rural households in kitchen and living room. The overall Geometric Mean (Geometric Standard Deviation) of ACH across households were found to be 0.43 (4.3) in the kitchen and 0.32 (2.7) in the living room. Obtaining the air changes per hour or ventilation rates from the decay curve of concentrations in the near vicinity of the pollutant source will lead to significant over-estimates. Our findings indicate that there is currently a substantial over-estimate based on using an incorrect model to derive the ACH values.

Frontiers in Microbiology, 2019

Despite their potential importance with regard to tobacco-related health outcomes, as well as the... more Despite their potential importance with regard to tobacco-related health outcomes, as well as their hypothesized role in the production of tobacco-specific N-nitrosamines, bacterial constituents of tobacco products lack characterization. Specifically, to our knowledge, there has been no comprehensive characterization of the effects of storage conditions on the bacterial communities associated with little cigars and cigarillos. To address this knowledge gap, we characterized the bacterial community composition of the tobacco and wrapper components of the following four products: Swisher Sweets Original; Swisher Sweets, Sweet Cherry; Cheyenne Cigars Full Flavor 100's; and Cheyenne Menthol Box. Each product was stored under three different conditions of temperature and relative humidity to mimic different user storage conditions: room (20 • C 50% RH), refrigerator (5 • C 18% RH) and pocket (25 • C 30% RH). On days 0, 5, 9 and 14, subsamples were collected, the wrapper and tobacco were separated, and their total DNA was extracted separately and purified. Resulting DNA was then used in PCR assays targeting the V3 V4 region of the bacterial 16S rRNA gene, followed by sequencing using Illumina HiSeq 300bp PE. Resulting sequences were processed using the Quantitative Insights Into Microbial Ecology (QIIME) software package, followed by analyses in R using the Phyloseq and Vegan packages. A single bacterial phylum, Firmicutes, dominated in the wrapper subsamples whereas the tobacco subsamples were dominated by Proteobacteria. Cheyenne Menthol Box (CMB) samples were characterized by significant differential abundances for 23 bacterial operational taxonomic units (OTUs) in tobacco subsamples and 27 OTUs in the wrapper subsamples between day 0 and day 14 under all conditions. OTUs from the genera Acinetobacter and Bacillus significantly increased in the CMB tobacco subsamples, and OTUs from Bacillus, Streptococcus, Lactobacillus, and Enterococcus significantly increased in the CMB wrapper subsamples over time. These initial results suggest that the bacterial communities of little cigars and cigarillos are dynamic over time and varying storage conditions.

PLOS ONE, 2019

Despite their potential importance with regard to infectious and chronic diseases among tobacco u... more Despite their potential importance with regard to infectious and chronic diseases among tobacco users, microbial constituents of tobacco products lack characterization. Specifically, to our knowledge, there are no data describing the bacterial diversity of little cigars or cigarillos. To address this knowledge gap, we tested four brands of little cigars and cigarillos. Tobacco and wrapper subsamples (n = 132) were separately subjected to DNA extraction, followed by PCR amplification of the V3V4 hypervariable region of the 16S rRNA gene, and sequencing using Illumina HiSeq. Sequences were analyzed using QIIME and Phyloseq implemented in R. We identified 2,681 operational taxonomic units across all products. Significant differences in alpha and beta diversity were observed between Swisher Sweets and Cheyenne products. Alpha and beta diversity was also significantly different between tobacco and wrapper subsamples within the same product. Beta diversity analyses of only tobacco samples identified no significant differences in the bacterial microbiota of different lots of the same products; however, the microbiota in the wrapper differed significantly across lots for all brands. Overall, Firmicutes were found to dominate in the wrapper, whereas Proteobacteria were most abundant in the tobacco. At the genus level, Bacillus and Lactobacillus dominated in the wrappers, and Staphylococcus and Pseudomonas dominated in the tobacco. Our findings suggest that the bacterial microbiota of little cigars and cigarillos is diverse and differs significantly between the tobacco and the wrapper, and across brands. Future work is necessary to evaluate the potential public health implications of these findings.

Journal of Occupational and Environmental Hygiene, 2018

Supplemental Table 1. Recommended Data Elements from ACGIH-AIHA Joint Task Group Data Element Def... more Supplemental Table 1. Recommended Data Elements from ACGIH-AIHA Joint Task Group Data Element Definition A. Facility/Site Information A-1* Company/Organization Name of the company or organization that operates or is directly responsible for the facility (work establishment, work site, or premises). A-2* Facility Name Legal name of facility (work establishment, work site, or premises). A-3* Facility Address Facility street, city, state/province, and zip code/postal code. A-4* SIC Code Four-digit Standard Industrial Classification code for the facility (work establishment, site, or premises). Seven-digit SIC code may be used when available. A-5* Industrial Category Text description of the overall purpose(s), product(s), service(s), and activity(ies) of the facility (work establishment, site, or premises). Information supplements the more generic SIC code as recorded above. A-6* Contractor Information If survey involves contractor employees inside a larger facility (e.g., construction or maintenance contractors), record name, type, and SIC of contractor, and name of main contractor if necessary. A-7* Number of Employees Total number of employees in facility (establishment, site). If contractor in a larger workplace, also record number of contractor employees. B. Survey Tracking Information B-1* Survey Number (Reference Number) A unique number for tracking the survey and any associated report(s). B-2* Survey Date Date(s) survey was performed. B-3* Person Performing Survey Name, unique identifier (e.g., SSN, employee number), and position of the person responsible for the survey. B-4 Report Number Link to report with conclusions and recommendations of the survey. B-5 Is Follow-up Required? Do survey results or observations require follow-up? Coded: Yes, follow-up is required. No, follow-up is not required. B-6 Follow-up Summary Text summarizing the specific follow-up action(s) required or recommended (e.g., routine monitoring, protective equipment, installation of controls, medical surveillance, etc.). B-7 Person(s) Responsible for Follow-up Name, position, and SSN or employee number of the person(s) responsible for followup. Supplemental Table 1. Recommended Data Elements from ACGIH-AIHA Joint Task Group, continued Data Element Definition B-8 Date Follow-up Completed The date(s) when follow-up action(s) were completed. B-9* Quality Control Review Name, position, and SSN or employee number of the person who reviewed the survey data for accuracy and completeness. B-10* Date of Quality Control Review The date the quality control review was performed. B-11 General Survey Comments Additional comments. C. Work Area Information C-1* Building/Zone A distinct part of the facility (work establishment, work site). May be a building or a distinct zone within the facility (work establishment, work site). It is possible to have multiple building zones for a mobile employee. C-2* Room/Area Specific room or area within the building or zone. It is possible to have multiple rooms/areas for a mobile employee. C-3* Department Organizational or functional assignment of work area (e.g., assembly department, shipping and receiving department). Note that department may or may not represent a distinct physical area. C-4* Type of Work Area Type of work area. Coded: Open air. Enclosed indoor space (e.g., typical workroom or walled work area). Confined space (restricted space with reduced ventilation). Describe with text. Equipment cab (e.g., crane, bulldozer). Other. Describe with text.

NanoImpact, 2018

Improvement of methods to quantify the release and characterization of engineered nanomaterials (... more Improvement of methods to quantify the release and characterization of engineered nanomaterials (ENMs) from nano-enabled products is essential to enhance the accuracy and usability of environmental health and safety evaluations. An anticorrosive coating containing multi-wall carbon nanotubes (MWCNTs) was analyzed for nano-scale material and workplace exposure potential. Worker breathing zone measurements for elemental carbon (EC) and electron-microscopy-based structure counts showed negligible MWCNT exposure to workers during laboratory and spray-painting operations over the course of two 8-hour shifts (arithmetic mean inhalable EC and electron microscopy structure count concentrations were 6.47 μg/m 3 and 0.084 structures/cm 3 respectively). UV weathering prior to abrasion testing increased the nano-size fraction of released material as measured by a fast mobility particle sizer (FMPS) and visual inspection by SEM indicated increased presence of exposed MWCNTs embedded in the polymer matrix. However, no free MWCNTs were identified, despite evidence of MWCNTs embedded in airborne particles. TiO 2 , used as a pigment in the coating and not anticipated as a candidate for nano-specific scrutiny, contained a small fraction (3.5% in number) of nano-sized constituents (< 100 nm). This work emphasizes need for rigorous characterization of additive materials to properly assess potential health hazards and to better our understanding of what qualifies as "nano".

Journal of occupational and environmental hygiene, 2018

Despite substantial financial and personnel resources being devoted to occupational exposure moni... more Despite substantial financial and personnel resources being devoted to occupational exposure monitoring (OEM) by employers, workers' compensation insurers, and other organizations, the United States (U.S.) lacks comprehensive occupational exposure databases to use for research and surveillance activities. OEM data are necessary for determining the levels of workers' exposures; compliance with regulations; developing control measures; establishing worker exposure profiles; and improving preventive and responsive exposure surveillance and policy efforts. Workers' compensation insurers as a group may have particular potential for understanding exposures in various industries, especially among small employers. This is the first study to determine how selected state-based and private workers' compensation insurers collect, store, and use OEM data related specifically to air and noise sampling. Of 50 insurers contacted to participate in this study, 28 completed an online ...

Microbiome, Feb 15, 2017

There is a paucity of data regarding the microbial constituents of tobacco products and their imp... more There is a paucity of data regarding the microbial constituents of tobacco products and their impacts on public health. Moreover, there has been no comparative characterization performed on the bacterial microbiota associated with the addition of menthol, an additive that has been used by tobacco manufacturers for nearly a century. To address this knowledge gap, we conducted bacterial community profiling on tobacco from user- and custom-mentholated/non-mentholated cigarette pairs, as well as a commercially-mentholated product. Total genomic DNA was extracted using a multi-step enzymatic and mechanical lysis protocol followed by PCR amplification of the V3-V4 hypervariable regions of the 16S rRNA gene from five cigarette products (18 cigarettes per product for a total of 90 samples): Camel Crush, user-mentholated Camel Crush, Camel Kings, custom-mentholated Camel Kings, and Newport Menthols. Sequencing was performed on the Illumina MiSeq platform and sequences were processed using th...

Johns Hopkins University, Jun 9, 2021

Journal of Occupational and Environmental Hygiene, 2018

Journal of Occupational and Environmental Hygiene

Colors denotes the type of products: red- tobacco and blue- wrapper.</p

Extent of the Marcellus Shale in Garret and Allegany Counties in Western Maryland.</p

☯ These authors contributed equally to this work.

Journal of Occupational and Environmental Hygiene, 2018

Building and Environment, 2021

Frontiers in Microbiology, 2019

PLOS ONE, 2019

Journal of Occupational and Environmental Hygiene, 2018

NanoImpact, 2018

Journal of occupational and environmental hygiene, 2018

Microbiome, Feb 15, 2017