Air Samples Research Articles

Comparison of Operational Jet Fuel and Noise Exposure for Flight Line Personnel at Japanese and United States Air Bases in Japan

Flight line personnel are constantly exposed to noise and jet fuel while working on flight lines. Studies suggest that jet fuel in combination with noise affects hearing loss more than noise exposure alone. This study examined the combined effects of jet fuel and noise exposure on the hearing of flight line personnel stationed at Japan Air Self-Defense Force Air Bases (Hamamatsu, Matsushima, Hyakuri, Yokota, and Iruma) and US Air Force Air Bases (Kadena and Misawa) in Japan. Samples were collected from all participants, 97 flightline-exposed and 71 control volunteers, to measure their individual noise levels with a personal sound level meter and volatile organic chemicals (VOCs) with a chemical sampling pump during a single shift. Blood samples were collected post shift. Urine samples (entire void) were collected prior to the shift (morning first void) and post shift. VOCs were measured in air, blood, and urine. An audiometric test battery, consisting of immittance measurements, audiograms, distortion product otoacoustic emissions, and the auditory brain response, was conducted after the shift to examine the hearing of participants. Total VOCs in personal air samples were in the ppb range for each group. Tinnitus and temporary hearing loss were reported in audiological histories but were also present in some controls. Noise levels on the flight line were greater than the action level for requiring hearing protection and exceeded exposure limits, but all exposed subjects reported wearing hearing protection. Audiometric tests identified significant differences and trends between flight line and control personnel, indicating the potential for hearing disorders. In spite of very low levels of VOC exposure and wearing hearing protection for noise, there is still the potential for hearing issues in flight line personnel.

Wind Is a Primary Driver of Fungal Dispersal Across a Mainland-Island System.

Dispersal is one of the main processes shaping ecological communities. Yet, for species-rich communities in natural systems, the role of dispersal in community assembly remains relatively less studied compared to other processes. This is the case for fungal communities, for which predictable knowledge about where and how the dispersal propagules move across space is largely lacking. We sampled fungal communities at their dispersal stage in a lake mainland-island system in Finland, using a regular grid of 18 × 18 km, including sites on the mainland, islands and over the water. Fungal communities were screened by applying DNA barcoding to air samples. To assess the factors determining fungal dispersal, we modelled aerial fungal communities with a joint species distribution model, including spore traits, weather-related predictors, and spatial predictors. We found that the probability of occurrence of most species (and consequently species richness measured as the number of OTUs per sample) was lower in low-connectivity sites (water and isolated islands) compared to high-connectivity sites (mainland). There was a strong phylogenetic signal in how the fungal species responded to connectivity, indicating that some taxonomic groups are more dispersal limited than others, although such responses were not structured by their trophic guilds. Furthermore, wind speed influenced how species with different spore sizes responded to connectivity: in low-connectivity sites, species with large sexual spores were detected especially when wind was high, whereas, in high-connectivity sites, they were detected especially when wind was low. This study demonstrates that air fungal dispersal might be more predictable than previously considered and contributes to the mechanistic understanding of fungal air dispersal.

Critical Insights into Untargeted GC-HRMS Analysis: Exploring Volatile Organic Compounds in Italian Ambient Air

This study critically examines the workflow for untargeted analysis of volatile organic compounds (VOCs) in ambient air, from sampling strategies to data interpretation by using GC-HRMS. While untargeted approaches are well-established in liquid chromatography (LC) due to advanced-deconvolution tools and extensive metabolomic libraries, their application in gas chromatography (GC) remains less developed, particularly for VOCs. The high structural isomerism of VOCs and the relative novelty of GC-based untargeted methodologies present unique challenges, including limited software tools and reference libraries. Air samples from suburban and rural sites in central Italy were analyzed to explore chemical diversity and address methodological gaps. This study evaluates critical decisions, such as sampling strategies, extraction techniques, and data-processing workflows, highlighting the limitations of automated deconvolution tools and the need for manual validation. Results revealed distinct source contributions, with suburban areas showing higher levels of anthropogenic compounds and rural areas dominated by biogenic emissions. This work underscores the potential of GC-HRMS untargeted analysis to advance environmental chemistry, while addressing key pitfalls and providing practical recommendations for reliable application. By bridging methodological gaps, it offers a roadmap for future studies aiming to integrate untargeted and targeted approaches in air quality research.

Interpretation of indoor air surveillance for respiratory infections: a prospective longitudinal observational study in a childcare setting.

Sampling the air in indoor congregate settings, where respiratory pathogens are ubiquitous, may constitute a valuable yet underutilised data source for community-wide surveillance of respiratory infections. However, there is a lack of research comparing air sampling and individual sampling of attendees. Therefore, it remains unclear how air sampling results should be interpreted for the purpose of surveillance. In this prospective observational study, we compared the presence and concentration of several respiratory pathogens in the air with the number of attendees with infections and the pathogen load in their nasal mucus. Weekly for 22 consecutive weeks, we sampled the air in a single childcare setting in Belgium. Concurrently, we collected the paper tissues used to wipe the noses of 23 regular attendees: children aged zero to three and childcare workers. All samples were tested for 29 respiratory pathogens using PCR. Air sampling sensitively detected most respiratory pathogens found in nasal mucus. Some pathogens (SARS-CoV-2, Pneumocystis jirovecii) were found repeatedly in the air, but rarely in nasal mucus, whilst the opposite was true for others (Human coronavirus NL63). All three pathogens with a clear outbreak pattern (Human coronavirus HKU-1, human parainfluenza virus 3 and 4) were found in the air one week before or concurrent with the first detection in paper tissue samples. The presence and concentration of pathogens in the air was best predicted by the pathogen load of the most infectious case. However, air pathogen concentrations also correlated with the number of attendees with infections. Detection and concentration in the air were associated with CO2 concentration, a marker of ventilation and occupancy. Our results suggest that air sampling could provide sensitive, responsive epidemiological indicators for the surveillance of respiratory pathogens. Using air CO2 concentrations to normalise such signals emerges as a promising approach. KU Leuven; DURABLE project, under the EU4Health Programme of the European Commission; Thermo Fisher Scientific.

Investigating the respiratory and systemic effects of exposure to BTEX among municipal solid waste workers.

Workers at municipal solid waste (MSW) facilities may be exposed to a range of volatile organic compounds (VOCs). This study aimed to evaluate the potential systemic and respiratory effects, as well as to conduct cancer and non-cancer health risk assessments, associated with exposure to an important group of VOCs-Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX)-among MSW workers. For this purpose, 48 air samples were collected from an MSW facility (36 samples from the landfill and 12 samples from the transfer station) and from a green space serving as the control area (n=6), located in Hamedan, in the west of Iran, during the spring and summer of 2019. Additionally, 60 individuals (30 in the exposure group and 30 in the control group) underwent testing for inflammatory markers, blood factors, and respiratory function. The highest levels of all BTEX compounds were detected at the transfer station, while the lowest concentrations were found at the green space. The mean concentrations of total BTEX compounds were 127μg/m³, 42μg/m³, and 4μg/m³ for air samples collected from the transfer station, the landfill, and the green space, respectively, with Toluene being the dominant pollutant at all sampling sites. While all BTEX compound concentrations remained below the Reference Concentration (RfC) and Threshold Limit Value (TLV), high lifetime cancer risks (LCRs) for Benzene and Ethylbenzene were observed at certain sampling locations, particularly at the transfer station and the active zone of landfill, with LCR values exceeding acceptable thresholds. Biological monitoring of workers indicated that working at sites with higher concentrations of BTEX adversely impacted blood biomarkers and respiratory function. This emphasizes the need for more effective protective strategies to minimize exposure and address associated occupational hazards.

The identification of synthetic drug laboratories based on the detection of precursors.

The Netherlands is a small country but large in terms of production and trade in synthetic drugs, especially amphetamines and MDMA. In fact, Dutch criminals are global leaders, with networks and business practices all over the world. It's a billion dollar business, that forms a shadow economy with great appeal. Production of these drugs takes place at remote locations, in barns connected to farmhouses but also in residential areas where production locations are hidden in cellars and attics. In this study we developed a method that may be helpful to detect such illegal synthetic drug laboratories in suspected areas. An SPME sampler is used to passively collect air samples which are then analyzed for benzyl methyl ketone (BMK) and piperonyl methyl ketone (PMK), the precursors of respectively amphetamines and MDMA. The detection limit was 0.01 ng absolute for both compounds which means that BMK and PMK can be detected at concentrations comparable to other airborne VOCs with a sampling time of less than 10 min. Environmental conditions have only a limited influence on the uptake of BMK and PMK. In measurements in and around a simulated synthetic drug laboratory BMK and PMK could easily be detected inside the facility and even outside at distances up to 5 m. In a training laboratory facility of the police, BMK as well as PMK could be detected even while these compounds were no longer present in this facility. The identification of BMK and PMK was selective which was confirmed by measurements at 40 unsuspected locations where BMK and PMK were not detected in the presence of other compounds. The method can help to confirm the identification of illegal synthetic drug laboratories or a storage facility in suspected locations. While analysis in this study was done in the laboratory, analysis in practice may be possible using a mobile GC/MS system.

Scant Evidence for Long-Range Atmospheric Transport of Particle-Bound Benzotriazole Ultraviolet Stabilizers.

Despite benzotriazole UV stabilizers (BT-UVs) being widely used since the 1960s, few empirical data on their atmospheric presence exist. UV-328 was added to the Stockholm Convention on Persistent Organic Pollutants, based in part on model calculations indicating atmospheric long-range transport potential. We investigated the atmospheric occurrence of BT-UVs at multiple sites that differ greatly in their proximity to potential sources. UV-P, UV-328, UV-234, UV-326, UV-329, and UV-327 were quantified in active air samples collected in suburban Toronto, on Saturna Island in the Salish Sea, at Point Petre on Lake Ontario, and in Alert, Nunavut, as well as in XAD-resin based passive air samplers deployed at sites in British Columbia and Quebec. As the most volatile BT-UV, UV-P was present in the gas phase across all sampling locations, with higher concentrations in urban areas. The five less volatile BT-UVs were present only in active air samples from suburban Toronto and were not found above detection limits (0.03-1.7 pg·m-3) anywhere else. Empirical evidence thus does not support model predictions of long-range atmospheric transport of particle-bound BT-UVs. Predictions based on simple model calculations should be supported by empirical data if they are to be used as the basis for regulatory decisions.

P-2176. Validation of Air Sampling and Real-Time Quantitative Polymerase Chain Reaction for Measles Virus Surveillance: A Single-Center, Preliminary Assessment

Abstract Background During the early months of Chicago’s 2024 measles outbreak, many patients were admitted to local hospitals due to a lack of isolation housing in congregate settings. While the infection control potential of air sampling for viral pathogens is well described for viruses such as SARS-CoV-2, its utility for measles virus response is less clear. Here, we report a single center assessment of inpatient air sampling from airborne isolation rooms of patients with and without PCR-confirmed measles infection.Figure.Mean Measles Genome Copies in Four Rooms by Air Sampling Time Methods Aerosolsense samplers (ThermoFisher) were placed in 3 occupied and 1 unoccupied (negative control) airborne isolation rooms under negative pressure conditions. Air samples were collected at varying timeframes (30 minutes – 20 hours). Total nucleic acids were extracted from air samples within 24 hours of collection. Quantitative reverse transcription PCR (qRT-PCR) was performed to detect wildtype measles virus and genotype A (vaccine strain) measles virus; a gBlock DNA standard was included to estimate viral copy numbers. N450 amplification and Sanger sequencing were performed on selected positive samples to determine measles genotype.Table:Inpatient Measles Air Sampling Data at Different Time Intervals*per 5 μl cartridge nucleic acid extract, viral copies approximated using measles N1 DNA gBlock, ND: not done, UD: undetermined, NA: not applicable Results Air sampling methods were successful, with measles PCR positivity only in rooms with a measles. Measles patients were 2-3 days post rash onset. The air samples collected between 0.5 – 5 hours showed linearly-increasing measles viral load from 950-10,550 genome copies. [Figure] Samples collected at 20 hours did not show increased virus load compared to 2 hours, with mean 10,000 viral copies, indicating possible saturation over extended air sampling. Sequences derived from air samples were determined to be wildtype measles virus genotype D8 (the circulating genotype in Chicago at the time). [Table] Conclusion Air sampling in patient rooms allowed genotyping of measles virus in real-time and shows promise for describing the dynamics of measles viral load and potential for transmissibility. The utility of air sampling as a tool for measles surveillance and outbreak management warrants further testing in healthcare and congregate settings. Disclosures All Authors: No reported disclosures

P-249. Diverse populations of viable pathogenic moulds and Candida, including C. auris, are commonly recovered from air samples at two tertiary care hospitals

Abstract Background Airborne fungi are important nosocomial pathogens. However, there are scant data on populations of viable fungi in air from hospital environments.Table 1.Hospitals and units included in air sampling Methods We cultured air samples at least once/month beginning in May 2023 at 2 hospitals separated by 1.5 miles, 1 of which had new building construction [Table 1]. Air was collected with SASS 3100 (36,000 L/2 hrs onto dry filters) and SAS Super 100 (1,000 L directly onto MYE plates) samplers, at the following sites: Outside, lobby, nurse stations (NS) and rooms on units housing immunosuppressed hosts (protected (HEPA filter, positive pressure) and unprotected rooms). Processed filters (sonicated, un-sonicated) and plates were incubated at 30°C, and fungi identified by morphology and ITS sequencing.Table 2.Aspergillus positive air cultures at two hospitalsData from 2 hospitals are combined and presented as % of air samples with a given result. Results There was a hierarchy in air culture positivity for pathogenic moulds, which was similar at the 2 hospitals: outdoor cultures > lobbies > NS > unprotected rooms > protected rooms. The predominant fungus was Aspergillus fumigatus (68% and 6% of outdoor and protected room samples positive, respectively), followed by other Aspergillus spp [Table 2]. Other common moulds were Alternaria (48% outside +), Cladosporium (35% outside +), Fusarium (24% outside +) and Mucorales (17% outside +, including Rhizopus, Syncephalastrum racemosum and Mucor) [Table 3]. Candida was cultured at similar frequencies outside and inside hospitals ((overall + (range): 7% (3%-13%)); in rank order, spp. were C. glabrata (n=8), C. krusei (6), C. albicans (5), C. tropicalis (4), C. parapsilosis (3), C. auris (1). C. auris was recovered from a unit that was not known to house an infected pt.Table 3.Non-Aspergillus positive air cultures at two hospitalsData from 2 hospitals are combined and presented as % of air samples with a given result. Conclusion Potentially pathogenic fungi were commonly cultured from air samples inside and outside 2 hospitals in Pittsburgh, including within rooms housing immunosuppressed pts. Burdens were lower within hospitals than immediately outside. Fungi included moulds like Aspergillus spp., which are well-recognized airborne pathogens, and, surprisingly, Candida spp., which are not typically considered as such. Among the latter was C. auris, which was temporo-spatially distant from pts known to be infected at the hospitals. We are currently studying potential links between fungi recovered during surveillance and invasive fungal infections, including by whole genome sequencing. Disclosures Cornelius J. Clancy, MD, Cidara: Grant/Research Support|Gilead: Honoraria|Merck: Grant/Research Support|Scynexis: Advisor/Consultant|Shionogi: Advisor/Consultant|Venatorx: Advisor/Consultant Alexander Sundermann, DrPH, CIC, FAPIC, OpGen: Honoraria Graham M. Snyder, MD, SM, Infectious Diseases Connect: Advisor/Consultant

Temporal Variations in Environmental Quality in Kokori-Erhoike Flow Station, Kokori Community, Delta State. Nigeria

The Niger Delta region of Nigeria, characterized by extensive oil and gas activities, frequently experiences gas flaring, a significant environmental concern. This study aims to investigate the temporal variations in environmental quality near the Kokori-Erhoike Flow Station in Kokori Community, Delta State, with a focus on assessing pollution levels in air, water, and soil. Samples were collected from various strategic locations around the flow station, including air, water, and soil samples. Samples were analyzed for a range of parameters including Total Petroleum Hydrocarbons (TPH), heavy metals (such as zinc, chromium, cadmium, lead, and copper), and physicochemical properties like pH, temperature, dissolved oxygen (DO), and electrical conductivity. The analytical methods employed included Atomic Absorption Spectrophotometry (AAS) for heavy metal analysis, Gas Chromatography-Mass Spectometry (GC-MS) for TPH. Significant findings revealed elevated levels of PM10, and PM2.5 in the air, particularly during the June period, with PM2.5 concentrations exceeding WHO limits. Water sample analysis indicated high concentrations of TPH, especially in the June period, with levels rising from 1.67 mg/L to 2.91 mg/L at specific locations. Heavy metal contamination in water samples showed concentrations of lead (Pb) up to 0.54 mg/L and cadmium (Cd) up to 1.42 mg/L, surpassing WHO guidelines. Soil samples also exhibited high levels of heavy metals, with cadmium (Cd) concentrations up to 1.72 mg/kg and lead (Pb) concentrations up to 10.46 mg/kg. Pearson's correlation analysis highlighted strong positive correlations, such as between cadmium (Cd) and lead (Pb) (r = 0.876, p < 0.01), and zinc (Zn) and chromium (Cr) (r = 0.821, p < 0.01), suggesting common pollution sources, such as industrial discharges and agricultural runoff. The findings of this study indicate significant environmental degradation in the vicinity of the Kokori-Erhioke Flow Station due to gas flaring activities.

P-258. A Longitudinal Study on the Impact of Sink Interventions on Environmental Bioburden and Patient Infections within Two Intensive Care Units at an Academic Hospital

Abstract Background Patient room sinks are frequently identified as potential sources for hospital-associated infections (HAIs), but there are no clear recommendations for interventions to reduce sink-related pathogenic bioburden. We conducted one of the first longitudinal crossover trials to assess the impact of practical sink interventions in an academic hospital.Figure 1.Contamination levels in patient room sink p-trap and tap water between units over time.Black lines represent samples with CFU/mL above the limit of detection. Methods We conducted a 4-phase randomized crossover trial in a medical ICU (MICU) and burn ICU (BICU). Each phase was 8 weeks with a 2-week washout between phases: drain covers, point-of-use filters, both, or no intervention on patient room sinks by unit. Environmental samples from tap water, p-trap water, air, and swabs of the sink basin and adjacent surface were collected every 2 weeks from 5 patient room sinks per unit. Colony-forming units (CFU)/mL of non-tuberculous mycobacteria (NTM), carbapenem-resistant Enterobacterales (CRE), multidrug-resistant Enterobacterales (MDRE), and Stenotrophomonas maltophilia were calculated following MALDI-TOF speciation. Patient HAI results were also recorded. Results Without filters, 68.7% (68/99) of tap water samples were positive, compared to 2.2% (2/90) with filters (p< 0.05). P-trap samples were highly variable with high bioburden and no clear time trends at the room or unit level (Figure 1). Positive air and surface samples rarely occurred but were most common in the drain cover phase (12/135). Within rooms, environmental samples were primarily positive before patient clinical isolates of the same species (7/8). Tap water samples across both units were primarily positive for NTM (71/189) yet no study-room-associated NTM infections were identified. Conclusion We identified that sinks, particularly p-traps, present a consistent source of pathogenic bioburden with fluctuating populations yet rarely contributed to surface/air contamination with organisms of interest in ICU patient rooms. Neither intervention impacted p-trap colonization (CFU/mL). We found that point-of-use filters consistently and effectively removed NTM from tap water. Drain covers were not found to be a useful intervention for reducing surface bioburden. Future research on decolonizing pathogenic bacteria from patient room p-traps is needed. Disclosures Becky A. Smith, MD, UpToDate: royalties

P-698. Evaluating Modes of Influenza Transmission (EMIT-2): An Ongoing Controlled Human Influenza Virus Infection Transmission Trial (CHIVITT)

Abstract Background The relative importance of inhalation, spray, and touch transmission remains poorly understood. We implemented a randomized controlled trial incorporating community-acquired cases using behavioral, personal protective equipment, and environmental interventions as tools to understand the pathway of influenza transmission.Figure 1.Study design and timeline of cohorts with naturally infected influenza Donors Methods We recruited healthy volunteer Recipients and influenza Donors with PCR-confirmed community-acquired infection to a hotel quarantine. We randomized healthy volunteers to Intervention (hand hygiene and face shield) and Control Recipients. Donors and Recipients interacted in an “Event Room” with controlled ventilation (0.2–0.5 air changes per hour) and relative humidity (20-40%). We collected ambient air and personal bioaerosol exposure samples using NIOSH BC-251 samplers. We also deployed a novel cascade to liquid media bioaerosol sampler. Donors provided exhaled breath samples using a Gesundheit-II (G-II) sampler. We analyzed samples using dPCR and florescent focus assay.Figure 2.Viral RNA load in GII samples and MTS Results We ran four cohorts (February 2023 and January-February 2024); two with naturally infected influenza Donors (Figure 1). We exposed 11 Recipients (mean age: 36; 55% female) to 5 influenza Donors (mean age: 21; 80% female). Preliminary results show that eleven G-II fine (< 5µm), one G-II coarse (≥5µm) (Figure 2), four NIOSH ambient air (three ≥4µm and one 1-4µm), and three NIOSH personal bioaerosol exposure samples (two 1-4µm and one less than 1µm) were PCR positive. Virus was cultured from an ambient bioaerosol sample. No Recipient developed influenza-like illness or PCR-positive swabs; serology is pending. Conclusion We demonstrated that it is feasible to recruit Donors with new onset community-acquired influenza infections and expose Recipients under highly controlled conditions. Although initial experiments did not produce PCR-positive secondary infections, much will be learned by analyzing the immunity of the exposed Recipients and the inhaled dose of virus. This unique randomized controlled trial will provide a definitive assessment of the role of inhalation transmission and critical data on which to build effective interventions to prevent transmission. Disclosures Donald K. Milton, MD, DrPH, Lumen Bioscience, Inc: Advisor/Consultant|Lumen Bioscience, Inc: Stocks/Bonds (Private Company)

Unraveling Various Sources of Particulates Matter in Air-Dust Samples Collected from North India Through Elemental Mapping and Concentration Correlation Using Micro-Particle-Induced X-Ray Emission Spectroscopy.

Particulate matter (PM) found in the air is one of the major sources of pollution and air-borne diseases. Therefore, it is imperative to examine the elemental concentration distribution of the PM to identify the pollutant sources. In this study, it has demonstrated the capabilities of micro-particle-induced X-ray emission (micro-PIXE) spectroscopy in quantitative analysis of air samples collected from the Old Delhi outdoor market and indoor locations in the Panjab University hostel in the winter months. A 2-million electronvolts energetic scanning proton micro-beam (diameter ≈1 µm2) is used in micro-PIXE experiments generating high-resolution elemental maps of different regions of interest (ROI). Micro-PIXE along with the GeoPIXE analysis provides a non-destructive, standard-less, and ng/mg level-sensitive tool for the investigation of elemental distributions and highlighting pixels, which correlates to specific concentration ratios between elements at ROIs, thereby enabling a comprehensive understanding of the source of each elemental particulate. Si, Ca, and K detected in indoor PM suggest the source to soil erosion and crop burning, while high S levels in outdoor PM are primarily associated with coal power plants. Additionally, Sc, Ti, Cr, Mn, and Zn are found in outdoor samples, while indoor locations also contained trace amounts of V, Co, and Cu.

Air, Skin, and Biological Monitoring of French Fire Instructors’ Exposure to Particles/PAHs During Controlled Fire and Mitigation Strategies

Occupational exposure as a firefighter was recently classified as carcinogenic to humans by the IARC. Fire instructors’ exposure to carcinogenic PAHs is a major concern, and studies that have tried to assess the determinants of their exposure are scarce. An air and biomonitoring study was conducted in fire instructors performing simulated training exercises in enclosed containers. Air samples were collected, as well as urine samples from 22 firefighting instructors, and skin wipes were collected from FFs’ skin at the end of the exercises. PAH metabolites (1-hydroxypyrene, 3-hydroxybenzo(a)pyrene, 2/3-hydroxyfluorene, and 2/3-hydroxyphenanthrene) were measured in urine samples at three sampling times (beginning of shift, end of shift, and next morning). Airborne PAHs were dominated by low molecular weight compounds (naphthalene), and levels were as high as 67 µg·m−3 close to the containers, decreasing at higher distances. Skin contamination was observed both on the neck/face and hands/wrists of fire instructors and pilots. Ten times lower skin contamination was observed when nitrile undergloves were worn. High internal exposure was measured, with 1-hydroxypyrene and 3-hydroxybenzo(a)pyrene levels frequently exceeding maximum recommended values in occupational settings (up to 2.8 µmol/mol creatinine for 1-OHP, 14 µmol/mol creatinine for SOH-PAH, and 1.0 nmol/mol creatinine for 3-OHBaP), whereas benzene exposure was revealed to be very low. These types of exposure were found to derive both from dermal absorption (combustion products deposited on the skin) and inhalation (when removing SCBA outside the containers). Several recommendations are proposed in order to reduce both exposure routes (nitrile undergloves and half-masks in the vicinity of containers), harmonise decontamination (PPEs) and cleaning procedures, and prevent the dermal absorption of PAH from turnout gear. This study emphasises the complex PAH exposure profiles of fire instructors and characterises the main drivers of exposure, highlighting the need for better mitigation strategies.

How long does carbon stay in a near-pristine central Amazon forest? An empirical estimate with radiocarbon

Abstract. Amazon forests play a significant role in the global C cycle by assimilating large amounts of CO2 through photosynthesis and by storing C largely as biomass and soil organic matter. To evaluate the net budget of C in the Amazon, we must also consider the amplitude and timing of losses of C back to the atmosphere through respiration and biomass burning. One useful timescale metric that integrates such information in terrestrial ecosystems is the transit time of C, defined as the time elapsed between C entering and leaving the ecosystem; the transit time is equivalent to the age of C exiting the ecosystem, which occurs mostly through respiration. We estimated the mean transit time of C for a central Amazon forest based on the C age during ecosystem respiration (ER), taking advantage of the large variations in CO2 in the atmosphere below the forest canopy to estimate the radiocarbon signature of mean ER (Δ14CER) using Keeling and Miller–Tans mixing models. We collected air samples to evaluate changes in the isotopic signature of the main ER sources by estimating the δ13CER. We collected air samples in vertical profiles in October 2019 and December 2021 at the Amazon Tall Tower Observatory (ATTO) in the central Amazon. Air samples were collected in a diel cycle from two heights below the canopy (4 and 24 m above ground level (a.g.l.)). Afternoon above-canopy samples (79 and 321 m a.g.l.) were collected as the background. For the campaign of October 2019, the mean Δ14CER ranged from 24 ‰ to 41 ‰ with both Keeling and Miller–Tans methods. In December 2021, mean Δ14CER ranged from 53 ‰ to 102 ‰. The δ13CER showed a smaller variation, being −27.8 ‰ ± 0.3 ‰ in October 2019 and −29.0 ‰ ± 0.5 ‰ in December 2021. The Δ14CER estimates were compared with the record of atmospheric radiocarbon from the bomb period, providing estimates of mean transit time of 6 ± 2 years for 2019 and 18 ± 4 years for 2021. In contrast to steady-state carbon balance models that predict constant mean transit times, these results suggest an important level of variation in mean transit times. We discuss these results in the context of previous model-based estimates of mean transit time for tropical forests and the Amazon region. In addition, we discuss previous studies that indicate that approximately 70 % of assimilated carbon is respired as autotrophic respiration in the central Amazon. Our results suggest that newly fixed carbon in this terra firme tropical forest is respired within 1 to 2 decades, implying that only a fraction of assimilated C can act as a sink for decades or longer.

Occupational Health Risk Assessment of Microbiological Air Quality in Buhemba Small Scale Gold Mines, Tanzania

A large part of bio-aerosols is composed of biological particles such as bacteria, fungi, viruses, pollens, and their by-products such as endotoxins, metabolites, toxins, and other microbial fragments. These micro-organisms may affect human health with a wide range of adverse health effects including respiratory infections, allergies or toxic response in some individuals, especially susceptible ones. A cross-sectional study was conducted among purposely selected mining pits of Buhemba gold mine in Mara, Tanzania. To determine the microbial count, an agar strip loaded RCS® Microbial Air Sampler was used. Samples were collected at different microenvironments of the mining pit at a flow rate of 100 L min–1 for 5 minutes to yield a sample volume of 500 liters. Morphological characterization of both bacterial and fungal colonies was carried out followed by microscopic examination of fungal and gram-stained bacterial colonies. Regression analysis between mean bacterial and fungal spore counts with environmental factors like temperature and relative humidity was performed. The total aerobic bacteria concentration varied significantly (p value<0.05) between sampled pits (n=15), with the highest and lowest values of 3859 CFU/m3 and 1309 CFU/m3, respectively. However, there was no significant difference in total anaerobic bacteria concentration between sampled pits. The highest and lowest values of anaerobic bacteria were respectively 4284 CFU/m3 and 1190 CFU/m3. The highest and lowest values of total fungi concentration were 3314 CFU/m3 and 646 CFU/m3, respectively. High bacteria load that exceeds 1000 CFU/m3 as recommended by WHO was found in Buhemba gold mine.

IVF cycle safety when a positive passive air sampling occurs under laminar flow hood in absence of a detectable contamination in the embryo culture

Microbiological contamination in the embryo culture media might affect embryo early development and clinical outcomes during IVF procedures. Infections in the genital tract represent the most common causes of culture contamination, but also environmental air quality might have a detrimental effect on reproductive outcomes of infertile couples undergoing IVF procedures. Monitoring microbiological contamination in an embryology laboratory is mandatory and daily tests are performed under laminar vertical flow hood. In this study, we investigated the IVF outcome of procedures carried out during 5 years of laboratory activity when a positive passive air sampling occurs under laminar flow hood in the absence of clear contamination in the embryo culture. We performed 570 air samplings, and we isolated at least 1 CFU of microorganisms in the TSA settle plate in 13 cases (2.28%). No infections were suspected in the culture media given the absence of detectable microorganisms under the microscope or a turbidity/color change of culture media visible to the naked eye (0% contamination rate). There were no statistically significant differences in biochemical pregnancy, live birth rate, and abortion between the “contaminated” Group P and the “negative” Group N. Surprisingly, we found a better outcome in terms of clinical pregnancy rate in Group P as compared to Group N, a finding likely due to the accidental lower age of Group P (p = 0.0133). Data showed that, in the absence of a detectable contamination in the embryo culture media, IVF cycles are safe when an air positive sample occurs in Grade A environment.

Three-Dimensional (3D) Printing in Non-Industrial Spaces: A Summary of Emissions Evaluations in 11 School Settings.

Additive manufacturing or 3-dimensional (3D) printing is an emerging technology with increasing prevalence in non-industrial settings such as university and school settings. However, printers are often located in spaces not designed for this purpose. 3D-printer use in 11 university and K-12 schools was evaluated by identifying emissions using area air sampling for volatile organic compounds (VOCs) and particle counting instruments (PCIs) measuring ultrafine particulate (UFP) and evaluating controls to reduce potential exposure. Ventilation in printer locations was also characterized. VOCs and UFP were identified during 3D printing. Best-practice recommendations were provided to school health and safety staff to protect users, including workers and students. Recommendations included installing and implementing engineering controls, administrative controls, and personal protective equipment (PPE) to minimize exposure to 3D printer emissions. School health and safety staff can translate findings and recommendations for these 11 evaluations to identify 3D-printing areas on their campuses and use principles of industrial hygiene to protect workers and students and prevent the movement of emissions. VOCs and UFP were detected during 3D printing. There were opportunities to improve health and safety practices and reduce potential exposure when using 3D printing technologies.

Atmospheric pah concentrations in a semi-urban site: temporal variation, risk assessment, source identification and estimation of levels in diverse environments.

This study evaluates atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations in a semi-urban area, Görükle, Turkey, from June 2021 to February 2022. The average concentration of ∑16 PAHs was 24.85 ± 19.16 ng/m3, ranging from 6.70 to 59.11 ng/m3. Seasonal variations were observed, with winter concentrations approximately five times higher than those in summer, driven by increased residential heating emissions and adverse meteorological effects. The results were compared to literature values, revealing lower PAH levels than those found in other urban and industrial areas. Meteorological factors were statistically analyzed. PAH concentrations exhibited an inverse relationship with temperature and mixing height, while relative humidity showed a positive linear correlation. The study also estimated PAH concentrations in various environmental media using gas-particle partitioning and equilibrium models. The concentrations of PAHs in the particulate phase were minimal, suggesting that most PAHs were present in the gas phase. Additionally, the equilibrium concentrations of PAHs in soil, leaves, bark, and water were modeled, emphasizing the accumulation of heavier PAHs in these media yet 2- and 3-ring PAHs were predominant in the ambient air samples. Source apportionment and PCA studies identified vehicle emissions and combustion for heating purposes as the primary sources of pollution. However, air mass trajectory analysis indicated contributions from Kocaeli, an area with significant industrial activity. The cancer risk assessment yielded low risks for both adults and children.

A new portable sampler of atmospheric methane for radiocarbon measurements

Abstract. Radiocarbon (14C) is an optimal tracer of methane emissions, as 14C measurements enable distinguishing between fossil methane and biogenic methane (CH4). However, 14C measurements in atmospheric methane are still rare, mainly because of the technical challenge of collecting enough carbon for 14C analysis from ambient air samples. In this study, we address this challenge by advancing the system in Zazzeri et al. (2021) into a much more compact and portable sampler and by coupling the sampler with the MICADAS (MIni CArbon DAting System) accelerator mass spectrometry (AMS) system at ETH Zurich, using a gas interface. Here, we present the new sampler setup, the assessment of the system contamination and a first inter-laboratory comparison with LARA (Laboratory for the Analysis of Radiocarbon with AMS) at the University of Bern. With our sampling line, we achieved a very low blank, 0.7 µgC compared to 5.5 µgC in Zazzeri et al. (2021), and a sample precision of 0.9 %, comparable with other measurement techniques for 14CH4, while reducing the sample size to 60 L of air. We show that this technique, with further improvements, will enable routine 14CH4 measurements in the field for an improved understanding of CH4 sources.