Comparisons of indoor active and passive air sampling methods for emerging and legacy halogenated flame retardants in Beijing, China offices

One active and two passive air sampling configurations were deployed simultaneously in three offices in Beijing,China to test their comparability for sampling emerging and legacy halogenated flame retardants spanning a large range of octanoleair partition coefficients(KOA).Sampling in each office was carried out for three consecutive 28-day periods in the spring-summer of 2013.The active sampler was run for 2.5 h at different times every day for 28 days to parallel the passive samplers and sample a total volume comparable to that sampled by the passive samplers(~20 m^3).At the end of each 28-day sampling period,a separate active air sample was taken by running the sampler pump continuously for about 2.5 days.The comparability of measured concentrations varied between the air sampling configurations and for different compounds.The predominant compound measured in nearly all samples was BDE-209,a compound known to have heavy use in China.Several emerging flame retardants were also detected including DBE-DBCH,PBT,HBB,DDC-CO,and DBDPE.Very little of the tetra-hexabrominated BDEs associated with the technical PentaBDE product was observed.

Meta-Study of Particulate Detection Losses on Radioactive Air Sample Filters

Several mathematical relationships between air sample filter mass loading and the correlated analytical self-absorption factor were developed using data from other published research in this meta-study. Gross-alpha and -beta applications are addressed for this research. As filter media becomes loaded with particulate matter, there is potential for measurement losses due to self-absorption by mass loading. Components contributing to absorption include particulate dust, radioactive particulates, and filter material. Standards indicate a correction factor should be used when the penetration of radioactive material into the collection media or self-absorption of radiation by the material collected would reduce the detection rate by more than 5%. Previously, losses due to self-absorption have been reported up to 100% over a range up to ~10 mg⋅cm-2 mass loading. These absorption losses then can be used to determine a correction factor for sample results. For low mass loadings (e.g., ≤0.1 mg⋅cm-2) corrections factors in the 0.85 - 1 range have been recommended and used, while at higher mass loadings nearer to 10 mg⋅cm-2 correction factors closer to 0 (representing near 100% losses) are used. Based on data from published studies, the different methods for relating percent loss due to self-absorption to mass loading include linear, exponential, quadratic, and trinomial derived functions. Where applicable, both forced zero and non-forced zero results were evaluated. From the derived functions evaluated, the trinomial function provided the best fit. Once the sample filter mass loading is known, the trinomial function can be applied to estimate losses and the corresponding self-absorption factor. When applied to routine operating conditions for radiological facility stacks monitored at the Pacific Northwest National Laboratory for an average sample filter mass loading of 0.09 ± 0.12 (2σ) mg⋅cm-2 (excluding negative values and outliers) and a range from 0 - 0.24 mg⋅cm-2, the estimated trinomial function nominal self-absorption losses are less than 5% at 0.09 mg⋅cm-2 and less than 10% at 0.24 mg⋅cm-2. The trinomial function is one method that may be used to adjust the activity results of an air sample when the sample-specific mass loading is determined. The application of no correction factor when the ANSI/HPS N13.1-2021 guidance of a 5% threshold for loss is not reached with typical stack sample mass loadings may be reasonable in high-efficiency particulate air filtered systems. For simplicity, it would be conservative in assigning the self-absorption correction factor at the 5% threshold (i.e., 0.95) for general uses but in cases of heavy mass loading to calculate the factor.

Sources and Trends of Persistent Organic Pollutants at Three Passive Monitoring Sites in South Africa

The Stockholm Convention on Persistent Organic Pollutants (SCPOPs) is an international treaty that operates under the patronage of the United Nations (UN) to control certain chemicals that are considered persistent organic pollutants (POPs). They are of great concern because of their adverse effects on human health and the environment. Exposure to POPs may lead to cancer, infertility, respiratory infections, and other health complications. It is therefore critical to study the degree of human and environmental exposure to these POPs. Passive air sampling was conducted in South Africa to evaluate the presence and trends of persistent organic pollutants at Barberspan (rural agricultural), Vanderbijl Park (urban industrial) and Molopo Nature Reserve (isolated nature reserve). Samples were collected in 2012. Passive air samplers using poly were used for sampling. The Buchi System B-811 automatic extractor was used to analyze for dichloro-diphenyl-trichlorethane (DDT), pentachlorobenzene (PeCB), hexechlorobenzene (HCB) polychlorinated biphenyls (PCBs) and hexachlorocyclohexane (HCH). Sampling was conducted for a period of one year. POPs concentrations were generally low at all sites, but Vanderbijl Park had the highest concentrations. Seasonal changes in concentrations were much the same at the three sites with temperatures and wind patterns being major factors. The presence of these chemicals in Molopo Nature Reserve and Barberspan is evidence of long range transportation over dry semi desert areas. Back-trajectories indicate possible sources, including areas where DDT is used for malaria control. The presence of POPs is areas they have never been in use poses health and environmental risks in these areas.

Novel aerosol detection platform for SARS–CoV–2:Based on specific magnetic nanoparticles adsorption sampling and digital droplet PCR detection

The SARS–CoV–2 virus is released from an infectious source(such as a sick person)and adsorbed on aerosols,which can form pathogenic microorganism aerosols,which can affect human health through airborne transmission.Efficient sampling and accurate detection of microorganisms in aerosols are the premise and basis for studying their properties and evaluating their hazard.In this study,we built a set of sub-micron aerosol detection platform,and carried out a simulation experiment on the SARS–CoV–2 aerosol in the air by wet-wall cyclone combined with immunomagnetic nanoparticle adsorption sampling and ddPCR.The feasibility of the system in aerosol detection was verified,and the influencing factors in the detection process were experimentally tested.As a result,the sampling efficiency was 29.77%,and extraction efficiency was 98.57%.The minimum detection limit per unit volume of aerosols was 250 copies(102copies/m L,concentration factor 2.5).

Levels and Sources of Atmospheric Polycyclic Aromatic Hydrocarbons Surrounding an Oil Refinery in Curacao

This research measured ambient levels of polycyclic aromatic hydrocarbons (PAHs) surrounding a petrochemical complex on the island of Curacao using passive air sampling. In addition, source elucidation of PAHs was conducted using concentration profiles, distribution profiles, binary diagnostic ratios and factor analysis. Passive air samplers with polyurethane foam collection disks (PAS-PUFs) were deployed in 2011 (n = 43) and in 2014 (n = 30) to evaluate the extent of the emission plume as well as spatial and temporal differences in ambient PAH concentrations. In general, ambient PAH concentrations in Curacao were consistent with other urban and industrialized regions of the world;however, the levels measured downwind of Isla Refineriá petrochemical complex were among some of the highest reported ambient PAHs globally. Ambient PAH concentrations ranged from 1.2 to 790 ng/m3 in 2011 and 27 to 660 ng/m3 in 2014, demonstrating no temporal differences. However, significant spatial differences were detected between samples collected upwind and downwind of the petrochemical complex. Significantly higher ambient PAH concentrations were found in the samples collected downwind of the petrochemical complex compared to those upwind in 2014

Determination of 15 phthalate esters in air by gas-phase and particle-phase simultaneous sampling

Based on previous research, the sampling and analysis methods for phthalate esters （PAEs） were improved by increasing the sampling flow of indoor air from 1 to 4 L/min, shortening the sampling duration from 8 to 2 hr. Meanwhile, through the optimization of chromatographic conditions, the concentrations of 9 additional PAE pollutants in indoor air were measured. The optimized chromatographic conditions required a similar amount of time for analysis as before, but gave high responsivity, the capability of simultaneously distinguishing 15 kinds of PAEs, and a high level of discrimination between individual sample peaks, as well as stable peak generation. The recovery rate of all gas-phase and particle-phase samples of the 15 kinds of PAEs ranged from 91.26% to 109.42%, meeting the quantitative analysis requirements for indoor and outdoor air sampling and analysis. For the first time, investigation of the concentration levels as well as characteristics of 15 kinds of PAEs in the indoor air from four different traffic micro-environments （private vehicles, busses, taxis and subways） was carried out, along with validation of the optimized sampling and analytical method. The results show that all the 9 additional PAEs could be detected at relatively high pollution levels in the indoor air from the four traffic micro-environments. As none of the pollution levels of the 15 kinds of PAEs in the indoor air from the 4 traffic micro-environments should be neglected, it is of great significance to increase the types of PAEs able to be detected in indoor air.

Seasonal trend of ambient PCDD/Fs in Tianjin City, northern China using active sampling strategy

The spatial concentrations, seasonal trends, profiles and congener pairs of ambient polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were investigated within a seasonally active sampling scheme during Jun 2008 and Jan 2009 in Tianjin City, northern China. The PCDD/F concentrations ranged 14.2-172 fg I-TEQ/m3 （average 69.3 fg I-TEQ/m3） in summer and （89.8-1.01） x 103 fg I-TEQ/m3 （average 509 fg I-TEQ/m3） in winter, respectively, except for the E-waste dismantling site where much higher values were observed （1.04 x 103 fg I-TEQ]m3 in summer and 7.123 x 103 fg I-TEQ/m3 in winter）. The results indicated a significantly seasonal trend with higher TEQ values in winter as compared with summer, which could be related to increased emission sources and seasonal variations of the atmospheric boundary layer height. 2,3,4,7,8-PeCDF was the dominant contributor to the total PCDD/F toxic equivalents, and 2,3,7,8-TCDD was detected at almost all the sampling sites in winter. Most of the similarly substituted PCDD/F congener pairs exhibited high correlations, suggesting that they might have similar environmental fate or sources. But different seasonal and spatial distributions of PCDD/F concentrations indicated that the emission sources might be intermittent.

Effect of a portable ultra-clean exponential airflow unit on the particle distribution in an operating room

The effects of a mobile laminar airflow unit on the concentration, deposition and distribution of bacteria- carrying particles in an operating room are investigated. The exploration is carried out using numerical calculation schemes （computational fluid dynamics approach）. The model validation was performed through result comparisons with published measurement data from literature. Two types of mobile screen units were evaluated as an extension of turbulent-mixing operating-room ventilation. Airborne particle concentration/sedimentation was recorded with and without a screen unit on the operating table and two instrument tables. Both active and passive air sampling were examined and the results are compared. It was found that the additional mobile ultra-clean laminar airflow unit reduces the counts of airborne bacteria and surface contamination to a level acceptable for infection-prone surgeries.

Human viral pathogens are pervasive in wastewater treatment center aerosols

Wastewater treatment center（WTC） workers may be vulnerable to diseases caused by viruses, such as the common cold, influenza and gastro-intestinal infections. Although there is a substantial body of literature characterizing the microbial community found in wastewater, only a few studies have characterized the viral component of WTC aerosols,despite the fact that most diseases affecting WTC workers are of viral origin and that some of these viruses are transmitted through the air. In this study, we evaluated in four WTCs the presence of 11 viral pathogens of particular concern in this milieu and used a metagenomic approach to characterize the total viral community in the air of one of those WTCs. The presence of viruses in aerosols in different locations of individual WTCs was evaluated and the results obtained with four commonly used air samplers were compared.We detected four of the eleven viruses tested, including human adenovirus（h Ad V）,rotavirus, hepatitis A virus（HAV） and Herpes Simplex virus type 1（HSV1）. The results of the metagenomic assay uncovered very few viral RNA sequences in WTC aerosols, however sequences from human DNA viruses were in much greater relative abundance.