Aerosol Monitoring Research Articles

Spatial and Seasonal Variability of Remote and Urban Speciated Fine Particulate Matter in the United States.

The spatial and seasonal variability in the composition of major PM2.5 (particles with aerodynamic diameters less than 2.5μm) aerosol species in the United States were characterized using data from ground-based aerosol monitoring networks. The IMPROVE (Interagency Monitoring of Protected Visual Environments) network and the Chemical Speciation Network (CSN) operate in mostly rural/remote or urban/suburban sites, respectively. The networks have similar sampling schedules and analysis methods. Regional, monthly, and annual mean concentrations from 2019 to 2022 were calculated for ammonium sulfate (AS), ammonium nitrate (AN), particulate organic matter (POM), elemental carbon (EC), fine dust (FD), and sea salt (SS), as well as their relative contributions to reconstructed PM2.5 mass (RCFM). Organic aerosols were the largest contributor to RCFM across the United States (>40% annually, up to 80% monthly), with significant impacts from biomass smoke on POM and EC concentrations, contributions, and seasonality. AS concentrations and contributions were similar in urban and rural regions and contributed <20% annually to RCFM, considerably less than two decades ago. In general, urban concentrations were greater for AN, POM, and EC, suggesting additional urban sources. Some species, such as POM, FD, and AN, exhibited strong seasonal variability due to episodic source impacts or seasonal formation conditions. Evaluating the urban and rural monthly variability of major aerosol species is necessary for understanding the impacts of emission sources, regional transport, and atmospheric processes governing aerosol concentrations in the atmosphere.

Online Aerosol pH Detection Using 3D-Printed Microfluidic Devices with a Novel Magnetic SERS Sensor.

Accurate measurement of aerosol pH is crucial for understanding atmospheric processes and mitigating haze pollution. However, online detection of aerosol pH is challenging due to the complex composition of single-particle matter and trace components. This study develops a sensitive and selective sensor for the online detection of aerosol pH using surface-enhanced Raman spectroscopy (SERS). A novel Fe3O4@SiO2@Au-p-aminothiophenol (FA-pATP) sensor was fabricated using a layer-by-layer self-assembly method, achieving enhanced uniformity and increased density of SERS-active hotspots. Magnetic aggregation was employed to further amplify the Raman signal. This sensor was integrated into a 3D-printed microfluidic device to facilitate online monitoring of aerosol pH. The FA-pATP sensor exhibited a significant increase in peak intensity ratio with rising pH, demonstrating high sensitivity and responsiveness due to structural changes in the -NH2 groups of pATP under different pH conditions. The sensor demonstrated a linear pH response ranging from 5 to 11. The 3D-printed microfluidic device, coupled with the FA-pATP sensor, demonstrated notable performance in various environmental media, indicating strong anti-interference capabilities. The proposed sensor shows great promise for real-time online monitoring of aerosol pH, with broad applications in environmental monitoring.

Design, evaluation, and performance of versatile source sampling system (VS3) for monitoring and characterization of aerosols from area, point and line sources

Design, evaluation, and performance of versatile source sampling system (VS3) for monitoring and characterization of aerosols from area, point and line sources

ALICENET – an Italian network of automated lidar ceilometers for four-dimensional aerosol monitoring: infrastructure, data processing, and applications

Abstract. ​​​​​​​Vertically resolved information on aerosol particles represents a key aspect in many atmospheric studies, including aerosol–climate interactions and aerosol impacts on air quality and human health. This information is primarily derived by lidar active remote sensing, in particular with extensive networks currently in operation worldwide. In Italy, the Institute of Atmospheric Sciences and Climate (ISAC) of the National Research Council (CNR) established the ALICENET network of automated lidar ceilometers (ALCs) in 2015. Since then, ALICENET has grown as a cooperative effort of Italian institutions dealing with atmospheric science and monitoring, and it currently includes instruments run by regional environmental protection agencies, universities, research centres, and private companies. In the current configuration, the network makes use of both single-channel ALCs and dual-channel, polarisation-sensitive-system ALCs (referred to as PLCs). The systems operate in very different environments (urban, coastal, mountainous, and volcanic areas) from northern to southern Italy, thus allowing the continuous monitoring of the aerosol vertical distribution across the country. ALICENET also contributes to the EUMETNET programme E-PROFILE, filling an Italian observational gap compared to other EU member states, which generally run extended ALC networks through national meteorological services. In this work, we present the ALICENET infrastructure and the specifically developed data processing centralised at CNR-ISAC, converting raw instrumental data into quantitative, quality-controlled information on aerosol properties ranging from attenuated backscatter to aerosol mass and vertical stratifications. This setup allows us to get insights into the 4D aerosol field over Italy with applications from near-real-time monitoring to long-term analyses, examples of which are reported in this work. Specific comparisons of the ALICENET products to independent measurements obtained with different techniques, such as particulate matter (PM) concentrations from in situ samplers and aerosol optical depth (AOD) from sun photometers, are also included here, revealing the good performances of the ALICENET algorithms. Overall, ALICENET represents a valuable resource to extend the current aerosol observational capabilities in Italy and in the Mediterranean area, and it contributes to bridging the gap between atmospheric science and its application to specific sectors, among which are air quality, solar energy, and aviation safety.

Dust Aerosol Detection, Monitoring and Forecasting

Dust Aerosol Detection, Monitoring and Forecasting

The First Validation of Aerosol Optical Parameters Retrieved from the Terrestrial Ecosystem Carbon Inventory Satellite (TECIS) and Its Application

In August 2022, China successfully launched the Terrestrial Ecosystem Carbon Inventory Satellite (TECIS). The primary payload of this satellite is an onboard multi-beam lidar system, which is capable of observing aerosol optical parameters on a global scale. This pioneering study used the Fernald forward integration method to retrieve aerosol optical parameters based on the Level 2 data of the TECIS, including the aerosol depolarization ratio, aerosol backscatter coefficient, aerosol extinction coefficient, and aerosol optical depth (AOD). The validation of the TECIS-retrieved aerosol optical parameters was conducted using CALIPSO Level 1 and Level 2 data, with relative errors within 30%. A comparison of the AOD retrieved from the TECIS with the AERONET and MODIS AOD products yielded correlation coefficients greater than 0.7 and 0.6, respectively. The relative error of aerosol optical parameter profiles compared with ground-based measurements for CALIPSO was within 40%. Additionally, the correlation coefficients R2 with MODIS and AERONET AOD were approximately between 0.5 and 0.7, indicating the high accuracy of TECIS retrievals. Utilizing the TECIS retrieval results, combined with ground air quality monitoring data and HYSPLIT outcomes, a typical dust transport event was analyzed from 2 to 7 April 2023. The results indicate that dust was transported from the Taklamakan Desert in Xinjiang, China, to Henan and Anhui provinces, with a gradual decrease in the aerosol depolarization ratio and backscatter coefficient during the transport process, causing varying degrees of pollution in the downstream regions. This research verifies the accuracy of the retrieval algorithm through multi-source data comparison and demonstrates the potential application of the TECIS in the field of aerosol science for the first time. It enables the fine-scale regional monitoring of atmospheric aerosols and provides reliable data support for the three-dimensional distribution of global aerosols and related scientific applications.

Rapid Nucleation and Growth of Indoor Atmospheric Nanocluster Aerosol during the Use of Scented Volatile Chemical Products in Residential Buildings.

Scented volatile chemical products (sVCPs) are frequently used indoors. We conducted field measurements in a residential building to investigate new particle formation (NPF) from sVCP emissions. State-of-the-art instrumentation was used for real-time monitoring of indoor atmospheric nanocluster aerosol (NCA; 1-3 nm particles) size distributions and terpene mixing ratios. We integrated our NCA measurements with a comprehensive material balance model to analyze sVCP-nucleated indoor NCA dynamics. Our results reveal that sVCPs significantly increase indoor terpene mixing ratios (10-1,000 ppb), exceeding those in outdoor forested environments. The emitted terpenes react with indoor atmospheric O3 and initiate indoor NPF, resulting in nucleation rates as high as ∼105 cm-3 s-1 and condensational growth rates up to 300 nm h-1; these are orders of magnitude higher than those reported during outdoor NPF events. Notably, high particle nucleation rates significantly increase indoor atmospheric NCA concentrations (105-108 cm-3), and high growth rates drive their survival and growth to sizes that efficiently reach the deepest regions of the human respiratory system. We found sVCP-nucleated NCA to cause respiratory exposures and dose rates comparable to or exceeding those from primary aerosol sources such as gas stoves and diesel engines, highlighting their significant impact on indoor atmospheric environments.

Continuous emission monitoring the trace Sr from simulant aerosol emission with LIPS

Continuous emission monitoring (CEM) of strontium in aerosols is of great significance for air pollution prevention and industrial facilities emission monitoring. Laser-induced plasma spectroscopy (LIPS, also LIBS) is a promising technology for direct and online monitoring aerosols because of the advantages of no sample preparation, rapid analysis, and online detection. An enhanced LIPS setup with high detection sensitivity and short detection cycles is integrated to meet the demand for continuous monitoring of trace element aerosols. The continuous monitoring of strontium in aerosols is introduced with an improved LIPS setup. The setup is calibrated and tested with different concentrations of strontium aerosols generated by aerosol generators. The enhanced LIPS setup can quantify 22 ng/m3 strontium in aerosol within 10 min. Based on experiments, a calibration curve for the strontium aerosol is established and the limit of detection (LOD) of the setup reaches 1.8 ng/m3, which meets the need for continuous monitoring of trace elements.

Microfluidics-based condensation bioaerosol sampler for multipoint airborne virus monitoring

To facilitate rapid monitoring of airborne viruses, they must be collected with high efficiency and concentrated in a small volume of a liquid sample. In addition, the development of low-cost miniaturized samplers is essential for multipoint monitoring. Thus, in an attempt to fulfill these requirements, this study developed a microfluidic condensation bioaerosol sampler (MCBS). The developed sampler comprised two parts: a virus growth section and a virus droplet-to-liquid sample conversion section, each of which was fabricated on a chip using microfluidic technology. The condensation nucleus growth technique used in the virus growth section grew nanometer-sized airborne viruses into micro-sized droplets, making it possible to collection of viruses easier and with high efficiency. In addition, the virus droplet-to-liquid sample conversion section controlled the transport of droplets based on electrowetting technology. This enabled the collected airborne viruses to be concentrated in tens of microliters of the liquid sample. To evaluate the performance of both the sections, the virus dropletization, virus collection efficiency, and virus droplet-to-liquid sample conversion efficiency were evaluated through quantitative experiments. H1N1 and HCOV-229E viruses were used to conduct quantitative experiments on MCBS. We could obtain virus liquid samples with at 72.8- and 89.9-times higher concentration through 1:1 evaluation with a commercial sampler. Thus, the developed sampler facilitated efficient collection and concentration of airborne viruses in a compact, cost-effective manner. This is expected to facilitate rapid and accurate multipoint monitoring of viral aerosols.

Fungal aerosol and particulate matter in horse stables in Poland

Horses stay in different types of stables; especially during the cold season, they stay inside for most of the day. A stable is also a place where many people spend quite a lot of time either as employees who care for and train horses or as equine enthusiasts. Keeping horses in stables causes their constant exposure to high concentrations of particulate matter (PM) and molds in the air inside these facilities. The study was conducted in Udórz Stud Farm located in the southern region of Poland. It was carried out in two different types of stables: three runners and two box stables. The study continued for 2 years; samples were collected in each season of the year. The following devices were used: a six-stage Andersen-Graseby cascade impactor, the DustTrak™ II Aerosol Monitor 8530. The obtained results allowed for the conclusion that horses kept in box stables are exposed to lower concentrations of molds and yeasts than those kept in runners. Molds dominated in the stable air during humid periods—spring and autumn—while yeasts were more prominent during summer and winter. It was observed that cleaning stables reduces the morphotic elements of fungi in the air, even though it results in a higher level of particulate matter in the stable air. It should be noted that microclimate conditions were optimal for horses practically throughout the whole year.Key points• In stables, there is a high level of air intoxication, both by yeast and by mold fungi• The concentrations of fungi in the air depend on the season and the stable cleaning procedure• The PM concentrations depend on the type of stable

Assessment of PM2.5 Concentration at University Transit Bus Stops Using Low-Cost Aerosol Monitors by Student Commuters.

Particulate matter of 2.5 µm and smaller (PM2.5) is known to cause many respiratory health problems, such as asthma and heart disease. A primary source of PM2.5 is emissions from cars, trucks, and buses. Emissions from university transit bus systems could create zones of high PM2.5 concentration at their bus stops. This work recruited seven university students who regularly utilized the transit system to use a low-cost personal aerosol monitor (AirBeam) each time they arrived at a campus bus stop. Each participant measured PM2.5 concentrations every time they were at a transit-served bus stop over four weeks. PM2.5 concentration data from the AirBeam were compared with an ADR-1500 high-cost monitor and EPA PM2.5 reference measurements. This methodology allowed for identifying higher-than-average concentration zones at the transit bus stops compared to average measurements for the county. By increasing access to microenvironmental data, this project can contribute to public health efforts of personal protection and prevention by allowing individuals to measure and understand their exposure to PM2.5 at the bus stop. This work can also aid commuters, especially those with pre-existing conditions who use public transportation, in making more informed health decisions and better protecting themselves against new or worsening respiratory conditions.

Sulfate Formation Driven by Wintertime Fog Processing and a Hydroxymethanesulfonate Complex With Iron: Observations From Single‐Particle Measurements in Hong Kong

AbstractFog processing has a significant impact on sulfur chemistry in the atmosphere. This study analyzed three winter fog events in Hong Kong using single‐particle aerosol mass spectrometry (SPAMS) and a Monitor for AeRosols and GAses in ambient air (MARGA). Black carbon (BC)‐related carbonaceous particles with substantial sulfate amounts comprised the largest particle number fraction (56.7%). Sulfate mass concentration decreased during fog due to the cloud's effective scavenging, but fog processing notably promoted sulfate formation at the single‐particle level (average peak area increases of 31.2%). Hydroxymethanesulfonate (HMS), an important S(IV) compound and fog tracer, was identified accounting for up to 12% by particle number fraction. Although pH showed a positive correlation (r = 0.53–0.69) with HMS particles in each fog scenario, a negative overall correlation (r = −0.51) was observed. Further analysis revealed that the higher aerosol acidity (pH 0.65–3.11), promoted Fe dissolution, leading to 49% of HMS particles being mixed with Fe, which potentially facilitated sulfate formation via the Fenton reaction. Additionally, around 40% of HMS‐Fe particles are mixed with oxalate, thereby warranting further attention for their potential to cause more intricate sulfur oxidation processes. This study reveals the initial identification of a high mixed‐state of HMS‐Fe, which could potentially serve as a crucial avenue for the formation of sulfate on individual particulate matter. Considering the persistent augmentation of aerosol acidity in the Asian region, this phenomenon necessitates further investigation and attention.

The observation of atmospheric HONO by wet-rotating-denuder ion chromatograph in a coastal city: Performance and influencing factors

Due to the significance of atmospheric HONO as a reservoir for radicals and the presence of substantial unknown sources of HONO, there is a pressing need for accurate and consistent measurement of its concentration. In this study, we compared the measurements obtained from the monitor for aerosols and gases in ambient air (MARGA) based on wet chemical method with those from the incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) based on optical method to assess the suitability of the MARGA instrument for accurate HONO detection. The diurnal patterns obtained by the two instruments are similar, with peaks at 8 a.m. and lows at 5 p.m. Over the course of the observation period, it was often observed that HONO concentrations recorded by the MARGA instrument consistently exceeded those obtained through the IBBCEAS technique, accounting for approximately 91.33% of the total observation time. Throughout the entire observation period, the R2 value between the two instruments was 0.49, indicating relatively good correlation. However, with a slope of only 0.27, it suggests poor agreement between the two instruments. Furthermore, the R2 and slopes between the two instruments vary with the seasons and day-night. The larger the quartile values of NO2, NH3, and BC, the greater the slopes of both MARGA and IBBCEAS instruments, and the higher the concentrations of NO2, NH3, and BC (indicator of semivolatile oxidizable hydrocarbons), the greater the differences between the two instruments, all indicating that NH3 may promote the reaction of NO2 with semivolatile oxidizable hydrocarbons to produce HONO. The O3 with its strong oxidizing properties may cause underestimation in the MARGA instrument by oxidizing NO2− to NO3− in the absorbing solution. It is challenging to derive a universal correction formula due to the interference of various chemical substances. Hence, MARGA should not be used for HONO research in the future.

Innovative aerosol hygroscopic growth study from Mie–Raman–fluorescence lidar and microwave radiometer synergy

Abstract. This study focuses on the characterization of aerosol hygroscopicity using remote sensing techniques. We employ a Mie–Raman–fluorescence lidar (Lille Lidar for Atmospheric Study, LILAS), developed at the ATOLL platform, Laboratoire d'Optique Atmosphérique, Lille, France, in combination with the RPG-HATPRO-G5 microwave radiometer to enable continuous aerosol and water vapor monitoring. We identify hygroscopic growth cases when an aerosol layer exhibits an increase in both aerosol backscattering coefficient and relative humidity. By examining the fluorescence backscattering coefficient, which remains unaffected by the presence of water vapor, the potential temperature, and the absolute humidity, we verify the homogeneity of the aerosol layer. Consequently, the change in the backscattering coefficient is solely attributed to water uptake. The Hänel theory is employed to describe the evolution of the backscattering coefficient with relative humidity and introduces a hygroscopic coefficient, γ, which depends on the aerosol type. The particularity of this method revolves around the use of the fluorescence which is employed to take into account and correct the aerosol concentration variations in the layer. Case studies conducted on 29 July and 9 March 2021 examine, respectively, an urban and a smoke aerosol layer. For the urban case, γ is estimated as 0.47 ± 0.03 at 532 nm; as for the smoke case, the estimation of γ is 0.5 ± 0.3. These values align with those reported in the literature for urban and smoke particles. Our findings highlight the efficiency of the Mie–Raman–fluorescence lidar and microwave radiometer synergy in characterizing aerosol hygroscopicity. The results contribute to advance our understanding of atmospheric processes, aerosol–cloud interactions, and climate modeling.

Laser-induced 2D/0D graphene-nanoceria freestanding paper-based films for on-site hydrogen peroxide monitoring in no-touch disinfection treatments

A one-shot CO2 laser-based strategy to generate conductive reduced graphene oxide (rGO) decorated with nanoceria (nCe) is proposed. The 2D/0D rGO-nCe films, integrated as catalytic sensing layers in paper-based sensors, were employed for on-site monitoring of indoor fogging treatments against Listeria monocytogenes (Lm), a ubiquitous pathogenic bacterium. The rGO-nCe laser-assisted synthesis was optimized to preserve the rGO film morphological and electron-transfer features and simultaneously integrate catalytic nCe. The films were characterized by microscopical (SEM), spectroscopical (EDX, Raman, and FTIR), and electrochemical techniques. The most performing film was integrated into a nitrocellulose substrate, and the complete sensor was assembled via a combination of xurography and stencil printing. The rGO-nCe sensor's catalytic activity was proved toward the detection of H2O2, obtaining sensitive determination (LOD = 0.3 µM) and an extended linear range (0.5–1500 µM). Eventually, the rGO-nCe sensor was challenged for the real-time continuous monitoring of hydrogen peroxide aerosol during no-touch fogging treatment conducted following the EU’s recommendation for biocidal product use. Treatment effectiveness was proved toward three Lm strains characterized by different origins, i.e., type strain ATCC 7644, clinical strain 338, and food strain 641/6II. The sensor allows for discrimination and quantification treatments at different environmental biocidal amounts and fogging times, and correlates with the microbiological inhibition, promoting the proposed sensor as a useful tool to modulate and monitor no-touch treatments.Graphical

Variation in aerosol generation by surgical modality during oropharyngeal and laryngeal surgery.

The objectives were to determine the surgical modality with the lowest aerosol and droplets generated by commonly used modalities in oropharyngeal and laryngeal surgery. A simulation of oropharyngeal and laryngeal surgery was set up using fresh sheep heads. Four common surgical modalities were utilized: cold steel, electrocautery, coblation, and microdebrider. The resultant aerosol generated was evaluated using two measurement modalities at two key positions in the theater. (1) DustTrak Pro Aerosol Monitor was used to measure the concentration of particles. (2) Fluorescein dye coated on the oropharynx and larynx, and the resultant scatter on paper. Electrocautery and coblation produced statistically significant increases in the concentration of aerosols (p < .001). Microdebrider and cold steel instrumentation produced the least aerosols. No measurable fluorescein droplets were noted for all four modalities. Electrocautery and coblation produced higher concentrations of aerosols. Mitigation factors should be considered with instruments with increased aerosolization. These modalities show low droplet-related infection risk.

Enhancing mobile aerosol monitoring with CE376 dual-wavelength depolarization lidar

Abstract. We present the capabilities of a compact dual-wavelength depolarization lidar to assess the spatiotemporal variations in aerosol properties aboard moving vectors. Our approach involves coupling the lightweight Cimel CE376 lidar, which provides measurements at 532 and 808 nm and depolarization at 532 nm, with a photometer to monitor aerosol properties. The assessments, both algorithmic and instrumental, were conducted at ATOLL (ATmospheric Observatory of LiLle) platform operated by the Laboratoire d'Optique Atmosphérique (LOA), in Lille, France. An early version of the CE376 lidar co-located with the CE318-T photometer and with a multi-wavelength Raman lidar were considered for comparisons and validation. We developed a modified Klett inversion method for simultaneous two-wavelength elastic lidar and photometer measurements. Using this setup, we characterized aerosols during two distinct events of Saharan dust and dust smoke aerosols transported over Lille in spring 2021 and summer 2022. For validation purposes, comparisons against the Raman lidar were performed, demonstrating good agreement in aerosol properties with relative differences of up to 12 % in the depolarization measurements. Moreover, a first dataset of CE376 lidar and photometer performing on-road measurements was obtained during the FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality) field campaign deployed in summer 2019 over the northwestern USA. By lidar and photometer mapping in 3D, we investigated the transport of released smoke from active fire spots at William Flats (northeast WA, USA). Despite extreme environmental conditions, our study enabled the investigation of aerosol optical properties near the fire source, distinguishing the influence of diffuse, convective, and residual smoke. Backscatter, extinction profiles, and column-integrated lidar ratios at 532 and 808 nm were derived for a quality-assured dataset. Additionally, the extinction Ångström exponent (EAE), color ratio (CR), attenuated color ratio (ACR), and particle linear depolarization ratio (PLDR) were derived. In this study, we discuss the capabilities (and limitations) of the CE376 lidar in bridging observational gaps in aerosol monitoring, providing valuable insights for future research in this field.

Development, Demonstration, and Evaluation of Routine Monitoring of Aerosol Carbon, Oxygen, and Sulfur Content.

Traditional online measurements of the chemical composition of particulate matter have relied on expensive and complex research-grade instrumentation based on mass spectrometry and/or chromatography. However, routine monitoring requires lower-cost alternatives that can be operated autonomously, and such tools are lacking. Routine monitoring of particulate matter, especially organic aerosol, relies instead on offline techniques such as filter collection that require significant operator effort. To address this gap, we present here a new online instrument, the "ChemSpot", that provides information on organic aerosol mass loading, volatility, and degree of oxygenation, along with sulfur content. The instrument grows particles with water condensation, impacts them onto a passivated surface with low heat capacity, and uses stepped thermal desorption of analytes to a combination of flame ionization detector (FID) and flame photometric detector (FPD) and then to a CO2 detector downstream of the FID/FPD setup. By relying on detectors designed for gas chromatography, calibration is achieved almost entirely through the introduction of gases without the need for regular introduction of particle-phase calibrants. Particle collection efficiency of greater than 95% was achieved consistently, and the collection cell was shown to rapidly and precisely heat to ∼800 °C at a rate as fast as 10 °C per second. Measurements of total organic carbon, volatility distribution of organic aerosol, total sulfur, and oxygen-to-carbon ratio (O:C) collected during a continuous multi-week period are presented here to demonstrate the autonomous operation of "ChemSpot". Colocated measurements with a mass spectrometer, an aerosol chemical speciation monitor (ACSM), show good correlation and relatively low bias between the instruments (mean absolute percentage error of 21% and 27% for organic carbon and equivalent sulfate measurements, respectively).

Correlation between Aerosol Particulates, Carcass Dirtiness, and Hygiene Indicators of Bovine Carcasses in the Abattoir Environment: Results of a Study in Italy

The objective of this study was to demonstrate the possible correlation of visible carcass contamination and abattoir aerosol quality with microbial hygiene criteria. A total of 279 bovine carcasses were analyzed on 23 different working days. The aerobic colony count and total coliforms on the carcasses were calculated together with the presence of Escherichia coli. To determine the visible contamination of carcasses, we used a 100 cm2 sheet of transparent, adhesive plastic material, applied to the side of the carcass, to collect all the particles, which were then counted against both black and white backgrounds. The daily particulate index in the abattoir aerosol was determined using an air sampler device. The results showed that aerobic colony counts, which ranged from 1.41 to 2.40 log cfu cm−2, total coliforms (from 0.00 to 0.73 log cfu cm−2), and E. coli presence (from 0.00% to 60% of the sampled carcasses per day) are not correlated with the carcasses’ visual dirtiness or the aerosol quality. The factor analysis showed a correlation between the three groups of variables investigated: group 1, representing “aerosol quality”, group 2, representing the “microbiology of the carcass”, and group 3, the “visual dirtiness of the carcass”. Thus, even though microbiology analysis is useful in diagnosing the microorganisms which the official veterinarian is unable to detect during the post-mortem inspection, it is ineffective in evaluating slaughtering procedures. Aerosol monitoring and the visual classification of carcass dirtiness, instead, could provide good indications of the slaughtering process and the quality of the abattoir environment, and guarantee control of manufacturing practices, protecting both animals’ and operators’ health.

A comparative study of a standard slit-to-agar sampler and a real-time bacterial detector

A comparison is presented of data from simultaneous measurements of airborne particles by a standard slit-to-agar sampler (STA) and of fluorescent particles by a real-time bacterial detector, Bio Aerosol Monitoring System (BAMS) during an evaluation regarding emitted airborne particles of a surgical clothing system in a test chamber. Data from simultaneous orientating measurements of airborne particles by a standard discrete particle counter are also discussed. The results show that in an environment with a low level of airborne particles including CFUs and man the only contamination source, there is a moderate correlation between the number of aerobic CFU and BAMS viable, i.e., fluorescence, particles, when the slit-to-agar sampler is registering/collecting within its detection level. Different environments need simultaneous measurements by an STA in aerobic CFU/m³ and by a BAMS in viable particles/m³ to set up the correlation between the two methods. Keywords: Airborne particles, controlled environment, CFU, fluorescent particles, real-time measurements, viable particles.