Comparative Performance Testing of Respirator versus Surgical Mask Using a Water Droplet Spray Model

BACKGROUND

During the SARS-CoV-2 pandemic, there was shortage of the standard respiratory protective equipment (RPE). The aim of this study was to develop a procedure to test the performance of alternative RPEs used in the care of COVID-19 patients.

METHODS

A laboratory-based test was developed to compare RPEs by total inward leakage (TIL). We used a crossflow nebulizer to produce a jet spray of 1-100 µm water droplets with a fluorescent marker. The RPEs were placed on a dummy head and sprayed at distances of 30 and 60 cm. The outcome was determined as the recovery of the fluorescent marker on a membrane filter placed on the mouth of the dummy head.

RESULTS

At 30 cm, a type IIR surgical mask gave a 17.7% lower TIL compared with an FFP2 respirator. At 60 cm, this difference was similar, with a 21.7% lower TIL for the surgical mask compared to the respirator. When adding a face shield, the TIL at 30 cm was further reduced by 9.5% for the respirator and 16.6% in the case of the surgical mask.

CONCLUSIONS

A safe, fast and very sensitive test method was developed to assess the effectiveness of RPE by comparison under controlled conditions.

Assessment of exposure of gas station attendants in Sri Lanka to benzene, toluene and xylenes

Exposure to benzene, toluene and p-, m-, o-xylene (BTX) was studied in 29 gas station attendants and 16 office workers in Sri Lanka. The aim of this study was to assess the exposure level and identify potential exposure mitigating measures. Pre- and post-shift samples of end-exhaled air were collected and analysed for BTX on a thermal desorption gas chromatography mass spectrometry system (TD-GC-MS). Urine was collected at the same timepoints and analysed for a metabolite of benzene, S-phenyl mercapturic acid (SPMA), using liquid chromatography-mass spectrometry (LC-MS). Environmental exposure was measured by personal air sampling and analysed by gas chromatography flame ionization detection (GC-FID). Median (range) breathing zone air concentrations were 609 (65.1-1960) μg/m³ for benzene and 746 (<5.0-2770) μg/m³ for toluene. Taking into account long working hours, 28% of the measured exposures exceeded the ACGIH threshold limit value (TLV) for an 8-h time-weighted average of 1.6 mg/m³ for benzene. Xylene isomers were not detected. End-exhaled air concentrations were significantly increased for gas station attendants compared to office workers (p < 0.005). The difference was 1-3-fold in pre-shift and 2-5-fold in post-shift samples. The increase from pre-to post-shift amounted to 5-15-fold (p < 0.005). Pre-shift BTX concentrations in end-exhaled air were higher in smokers compared to non-smokers (p < 0.01). Exposure due to self-reported fuel spills was related to enhanced exhaled BTX (p < 0.05). The same was found for sleeping at the location of the gas station between two work-shifts. Benzene in end-exhaled air was moderately associated with benzene in the breathing zone (r = 0.422; p < 0.001). Median creatinine-corrected S-phenyl mercapturic acid (SPMA) was similar in pre- and post-shift (2.40 and 3.02 μg/g) in gas station attendants but increased in office workers (from 0.55 to 1.07 μg/g). In conclusion, working as a gas station attendant leads to inhalation exposure and occasional skin exposure to BTX. Smoking was identified as the most important co-exposure. Besides taking preventive measure to reduce exposure, the reduction of working hours to 40 h per week is expected to decrease benzene levels below the current TLV.

Intrusion of chlorinated hydrocarbons and their degradation products from contaminated soil. Measurement of indoor air quality and biomonitoring by analysis of end-exhaled air

A historic soil contamination of chlorinated hydrocarbons from a former dry cleaning shop caused intrusion of vapors into a building currently used as bookshop. The aim of this study was to determine the indoor air quality and the uptake of soil contaminants and their degradation products. Samples of indoor air were collected over one week in the warm and one week in the cold season. Pre-shift and post-shift samples of end-exhaled air were collected from two employees. Chlorinated hydrocarbons were analyzed in indoor air and exhaled air samples using thermal desorption gas chromatography mass spectrometry (TD-GC-MS). Tetrachloroethylene (PER), and its degradation products trichloroethylene (TRI), 1,1-dichloroethylene (1,1-DCE), 1,2-cis-dichloroethylene (1,2-cis-DCE), 1,2-trans-dichloroethylene (1,2-trans-DCE), methylene chloride (MC) and vinyl chloride (VC) were determined in ambient air. PER was the prime contaminant with a week average (±sd) of 805.2 ± 598.6 μg/m³ in June 2016 and 1031 ± 499.3 μg/m³ in December 2017. MC, 1,2-cis-DCE and TRI were detected at concentrations below 2.3 μg/m³. 1,1-DCE and VC were not detected. In exhaled air PER, 1,1-DCE, and MC were detected in both June and December, whereas TRI, 1,2-cis-DCE and 1,2-trans-DCE were only detected on one or two days in the cold season. VC was not detected in exhaled air. For PER, the mean concentrations (±sd) in end-exhaled air increased from a five days (Mon-Fri) average pre-shift value of 22.2 ± 8.0 to a post-shift value of 52.6 ± 15.5 ng/L in the male shop owner (p < 0.01) and in the female cashier these values were 26.0 ± 3.6 and 63.6 ± 12.7 ng/L, respectively (p < 0.01). Intrusion of chlorinated soil contaminants resulted in contamination of indoor air above the current accepted indoor air level for PER of 250 μg/m³. For PER in end-exhaled air an accumulation over the workweek was not observed.

Influence of combined dust reducing carpet and compact air filtration unit on the indoor air quality of a classroom

Primary schools mostly rely on natural ventilation but also have an interest in affordable technology to improve indoor air quality (IAQ). Laboratory tests show promising results for dust reducing carpets and compact air filtration systems but there is no information available on the performance of these interventions in actual operating classrooms. An exploratory study was performed to evaluate a combination of the two systems in a primary school. Measurements of PM-10 and PM-2.5 were performed by filter sampling and aerosol spectrometry. Other IAQ parameters included black smoke (BS), volatile organic compounds (VOC), nitrogen dioxide (NO2) and formaldehyde. Both interventions were introduced in one classroom during one week, using another classroom as a reference. In a second week the interventions were moved to the other classroom, using the first as a reference (cross-over design). In three remaining weeks the classrooms were compared without interventions. Indoor IAQ parameters were compared to the corresponding outdoor parameters using the indoor/outdoor (I/O) ratio. When the classrooms were occupied (teaching hours) interventions resulted in 27-43% reductions of PM-10, PM-2.5 and BS values. During the weekends the systems reduced these levels by 51-87%. Evaluations using the change in I/O ratios gave comparable results. Levels of VOC, NO2 and formaldehyde were rather low and a contribution of the interventions to the improvement of these gas phase IAQ parameters was inconclusive.

Estrogenic and androgenic activities in total plasma measured with reporter-gene bioassays: relevant exposure measures for endocrine disruptors in epidemiologic studies?

Measurements of estrogenic and androgenic activities in total plasma with Chemically Activated LUciferase gene eXpression (CALUX®) bioassays could provide biologically relevant measures for exposure to endocrine disruptors in epidemiologic studies. The objective of this study was to explore the effects of a variety of sources of potential endocrine disruptors on estrogenic and androgenic activities in total plasma measured by CALUX®. Plasma samples and interview data on sources of potential endocrine disruptors were collected from 108 men with different exposures profiles. CALUX® measurements (BioDetection Services) involved human U2-OS cell lines controlled by the estrogen receptor alpha and the androgen receptor. Mean differences (beta) in 17β-estradiol equivalents (EEQs) and dihydrotestosterone equivalents (AEQs) between exposure groups were estimated using general linear models. Mean plasma AEQs and EEQs were 9.1×10(-1)ng/ml and 12.0pg/ml, respectively. Elevated AEQs were found in smokers (beta 1.9 (95%CI 0.1-3.6)×10(-1)ng/ml) and heavy drinkers (1.4 (0.2-3.1)×10(-1)ng/ml), and in men occupationally exposed to disinfectants (1.6 (0.3-3.5)×10(-1)ng/ml) or welding/soldering fumes (1.4 (-0.2-2.9)×10(-1)ng/ml). Occupational exposure to pesticides, disinfectants, and exhaust fumes seemed to be associated with increased plasma EEQs: 1.5 (-0.2-3.2)pg/ml, 2.1 (0.2-3.9)pg/ml, and 2.9 (0.6-5.2)pg/ml, respectively. Moderate to high plasma dioxin levels, measured in a subgroup by the dioxin-responsive CALUX®, were accompanied by a 20% increase in AEQs. This is the first study in which CALUX® was used to assess hormone activities in total plasma. Although the results are not yet readily interpretable, they indicate that these measurements can be valuable for epidemiologic studies on endocrine disruptors and give direction for further research.

Determination of exposure to benzene, toluene and xylenes in Turkish primary school children by analysis of breath and by environmental passive sampling

Benzene, toluene, m/p-xylene and o-xylene (BTX) are toxic volatile organic compounds and ubiquitous air pollutants. Smoking and consumer products are indoor sources of BTX, whereas traffic and industrial activities are primary sources contributing to outdoor levels of BTX. The aim of this study was to characterize exposure of children to BTX by personal air sampling using diffusive samplers and by analysis of end-exhaled air. For this study, 101 children of 10-11 years of age were recruited from four primary schools in Southern Turkey during the warm season (May 2008). Two schools were situated in a residential area near primary and secondary iron and steel works (Payas) and two schools were located in a non-industrialized city (Iskenderun). The children and their parents were visited at home for an interview and to identify possible sources of BTX in the residence. Median concentrations of benzene determined by diffusive samplers were higher in Payas (4.1 microg/m(3)) than in Iskenderun (2.7 microg/m(3), p<0.001). For toluene, no differences were observed, whereas for xylene isomers air concentrations tended to be lower for children living in Payas. The median end-exhaled air concentrations were 8.2, 29, 3.8, and 5.7 pmol/L for benzene, toluene, m/p-xylene and o-xylene, respectively (Payas), and 6.9, 25, 4.9, and 6.0 pmol/L, respectively (Iskenderun). Concentrations of toluene in end-exhaled air were 50% higher in children living with household members who smoked indoors (p<0.05) and benzene in end-exhaled air was more than 3-fold higher for those children who were exposed to tobacco smoke inside a vehicle (p<0.001). End-exhaled concentrations of benzene were also higher in children living in a residence with an attached garage (p<0.05). These exposure modifying factors were not identified when using the results obtained with diffusive samplers.

Characterisation of exposure to total and hexavalent chromium of welders using biological monitoring

Inhalation exposure to total and hexavalent chromium (TCr and HCr) was assessed by personal air sampling and biological monitoring in 53 welders and 20 references. Median inhalation exposure levels of TCr were 1.3, 6.0, and 5.4 microg/m(3) for welders of mild steel (MS, <5% alloys), high alloy steel (HAS, >5% alloys), and stainless steel (SS, >26% alloys), respectively. The median exposures to HCr compounds were 0.23, 0.20, and 0.08 microg/m(3), respectively. Median concentrations of TCr in urine, blood plasma and erythrocytes were elevated in all welders, compared with the corresponding median concentrations in the reference group (p<0.005). The TCr levels observed in plasma were two-fold higher in welders of SS and HAS than in welders of MS (p<0.01). Exposure to HCr as indicated by median total content of Cr in erythrocytes was 10 microg/L in welders of SS, MS and HAS. Uptake of TCr during the shift was confirmed for welders of SS by a median increase of urinary TCr from pre- to post-shift of 0.30 microg/g creatinine. For welders of MS and HAS as a group TCr was not increased.

Exposure to dust and particle-associated 1-nitropyrene of drivers of diesel-powered equipment in underground mining

A field study was conducted in two mines in order to determine the most suitable strategy for ambient exposure assessment in the framework of a European study aimed at validation of biological monitoring approaches for diesel exhaust (BIOMODEM). Exposure to dust and particle-associated 1-nitropyrene (1-NP) was studied in 20 miners of black coal by the long wall method (Czech Republic) and in 20 workers in oil shale mining by the room and pillar method (Estonia). The study in the oil shale mine was extended to include 100 workers in a second phase (main study). In each mine half of the study population worked underground as drivers of diesel-powered trains (black coal) and excavators (oil shale). The other half consisted of workers occupied in various non-diesel production assignments. Exposure to diesel exhaust was studied by measurement of inhalable and respirable dust at fixed locations and by personal air sampling of respirable dust. The ratio of geometric mean inhalable to respirable dust concentration was approximately two to one. The underground/surface ratio of respirable dust concentrations measured at fixed locations and in the breathing zones of the workers was 2-fold or greater. Respirable dust was 2- to 3-fold higher in the breathing zone than at fixed sampling locations. The 1-NP content in these dust fractions was determined by gas chromatography-mass spectrometry/mass spectrometry and ranged from 0.003 to 42.2 ng/m(3) in the breathing zones of the workers. In mine dust no 1-NP was detected. In both mines 1-NP was observed to be primarily associated with respirable particles. The 1-NP concentrations were also higher underground than on the surface (2- to 3-fold in the coal mine and 10-fold or more in the oil shale mine). Concentrations of 1-NP in the breathing zones were also higher than at fixed sites (2.5-fold in the coal mine and 10-fold in the oil shale mine). For individual exposure assessment personal air sampling is preferred over air sampling at fixed sites. This study also suggests that particle-associated 1-NP much better reflects the ambient exposure to diesel exhaust particles than dust concentrations. Therefore, measurement of particle-associated 1-NP is preferred over measurement of dust concentrations by gravimetry, when linking ambient exposure to biomonitoring outcomes such as protein and DNA adducts and excretion of urinary metabolites of genotoxic substances.

BIOMarkers for occupational diesel exhaust exposure monitoring (BIOMODEM)--a study in underground mining

Methods for the assessment of exposures to diesel exhaust were evaluated, including various biomarkers of internal exposure and early biological effects. The impact of possible biomarkers of susceptibility was also explored. Underground workers (drivers of diesel-powered excavators) at an oil shale mine in Estonia were compared with surface workers. Personal exposures to particle-associated 1-nitropyrene (NP) were some eight times higher underground than on the surface. Underground miners were also occupationally exposed to benzene and polycyclic aromatic hydrocarbons, as indicated by excretion of urinary metabolites of benzene and pyrene. In addition, increased O(6)-alkylguanine DNA adducts were detected in the white blood cells of underground workers, suggesting higher exposure to nitroso-compounds. However, no differences between underground and surface workers were observed in the levels of other bulky DNA adducts determined by 32P-postlabelling, or in DNA damage. The study indicated that smoking, diet and residential indoor air pollution are important non-occupational factors to consider when interpreting biomonitoring results.

Postulating a dermal pathway for exposure to anti-neoplastic drugs among hospital workers. Applying a conceptual model to the results of three workplace surveys

Dermal exposure to anti-neoplastic drugs has been suggested as a potentially important route of exposure of hospital workers. Three small-scale workplace surveys were carried out in several hospitals focusing on contamination by leakage from IV infusion systems; contamination by spilled urine of patients treated with anti-neoplastic drugs and particulate phase anti-neoplastic drugs in the air of outpatient and nursing clinics. A new visual scoring technique using a fluorescent tracer was developed. The method showed a very low limit of detection (0.02 microl of contamination) and a very high inter-observer agreement (ICC=0.99). Evaluation of IV systems and connectors showed distinct differences between the systems. It was estimated that 0.5-250 microg of a drug can become available for contamination during each infusion. Differences in average contamination between nurses were negligible in the experimental set-up. Widespread and frequent contamination due to spillage of contaminated urine was revealed and appeared not to be restricted to the patient's room. Airborne particulate concentrations went undetected for 80% of the measurements. However, in a few cases concentrations up to 2 ng/m(3) of cyclophosphamide were measured predominantly in a room of a patient treated with this anti-neoplastic drug. Based on these results and a recently proposed conceptual model for dermal exposure a most likely exposure scenario was postulated both for nurses involved in administering drugs and nurses caring for treated patients. Estimation of all relevant mass transport rates will be a challenge for the near future.