Measurements during episodes of African dust, made with two wideband integrated bioaerosol spectrometers (WIBSs), one on the northeastern coast of Puerto Rico and the other in the city of León, Spain, show unmistakable, bioaerosol-like fluorescing aerosol particles (FAPs) that can be associated with these dust episodes. The Puerto Rico event occurred during a major incursion of African dust during June 2020. The León event occurred in the late winter and spring of 2022, when widespread, elevated layers of dust inundated the Iberian Peninsula. Satellite and back-trajectory analyses confirm that dust from northern Africa was the source of the particles during both events. The WIBSs measure the size of individual particles in the range from 0.5 to 30 µm, derive a shape factor, and classify seven types of fluorescence from the FAPs. In general, it is not possible to directly determine the specific biological identity from fluorescence signatures; however, measurements of these types of bioaerosols in laboratory studies allow us to compare ambient fluorescence patterns with whole microbial cells measured under controlled conditions. Here we introduce some new metrics that offer a more quantitative approach for comparing FAP characteristics derived from particles measured under different environmental conditions. The analysis highlights the similarities and differences at the two locations and reveals differences that can be attributed to the age and history of the dust plumes, e.g., the amount of time that the air masses were in the mixed layer and the frequency of precipitation along the air mass trajectory.

The influence of biomass burning on aerosol size distributions, particle number and radiative forcing has been studied at a rural site in Spain. It has been found that air contaminated by aerosols from biomass burning presents four times the total number of particles registered in non-contaminated air. In the case of the smallest fraction of the fine mode, between 0.1 and 0.2 µm, the increase soars to over seven times the total number of particles. An analysis of the evolution of the count mean diameter in the fine mode (CMDf) in the 8 daily measurements has revealed a decrease of over 25

A number of controlled combustions have been carried out in the laboratory using samples of oats and barley straw collected in Spain in order to establish the characteristic particle spectra of these emissions. In addition, chemical compounds such as CO2, NO2 and NO and gravimetric variations have been registered during the combustion processes. For each combustible the burning phase has also been defined. Burning barley generates a higher number of particles in the fine mode (with a diameter of less than 0.5 μm) than oats (74% vs. 59%). The distributions of particles emitted during the flaming phase have been characterized, as well as during the previous and subsequent phases. The average geometric diameter reached its maximum during the flaming phase, with 0.53 ± 0.10 μm and 0.44 ± 0.04 μm for oats and barley, respectively. After the flaming phase, oat straw generates coarser particles than barley.

Indoor air quality is crucial for human health due to the significant time people spend at home, and it is mainly affected by internal sources such as solid fuel combustion for heating. This study investigated the indoor air quality and health implications associated with residential coal burning covering gaseous pollutants (CO, CO2 and total volatile organic compounds), particulate matter, and toxicity. The PM10 chemical composition was obtained by ICP-MS/OES (elements), ion chromatography (water-soluble ions) and thermal-optical analysis (organic and elemental carbon). During coal combustion, PM10 levels were higher (up to 8.8 times) than background levels and the indoor-to-outdoor ratios were, on average, greater than unity, confirming the existence of a significant indoor source. The chemical characterisation of PM10 revealed increased concentrations of organic carbon and elemental carbon during coal combustion as well as arsenic, cadmium and lead. Carcinogenic risks associated with exposure to arsenic exceeded safety thresholds. Indoor air quality fluctuated during the study, with varying toxicity levels assessed using the Aliivibrio fischeri bioluminescence inhibition assay. These findings underscore the importance of mitigating indoor air pollution associated with coal burning and highlight the potential health risks from long-term exposure. Effective interventions are needed to improve indoor air quality and reduce health risks in coal-burning households.

Abstract. Measurements during episodes of African dust, made with two Wideband Integrated Bioaerosol Spectrometers (WIBS), one on the northeastern coast of Puerto Rico and the other in the city of León, Spain, show unmistakable, bioaerosol-like fluorescing aerosol particles (FAP) that can be associated with these dust episodes. The Puerto Rico events occurred during a major incursion of African dust during June 2020. The León events occurred in the late winter and spring of 2022 when widespread, elevated layers of dust inundated the Iberian Peninsula. Satellite and back trajectory analyses confirm that dust from Northern Africa was the source of the particles during both events. The WIBS measures the size of individual particles in the range from 0.5 µm to 30 µm, derives a shape factor and classifies seven types of fluorescence from the FAP. In general it is not possible to directly determine the specific biological identity from fluorescence signatures, however, measurements of these types of bioaerosols in laboratory studies allow us to compare ambient fluorescence patterns with whole microbial cells measured under controlled conditions. Here we introduce some new metrics that offer a more quantitative approach for comparing FAP characteristics derived from particles measured under different environmental conditions. The analysis highlights the similarities and differences at the two locations and reveals differences that can be attributed to the age and history of the dust plumes, e.g., the amount of time that the air masses were in the mixed layer and the frequency of precipitation along the air mass trajectory.

Fungal spores, commonly found in the atmosphere, can trigger important respiratory disorders. The glycoprotein Alt a 1 is the major allergen present in conidia of the genus Alternaria and has a high clinical relevance for people sensitized to fungi. Exposure to this allergen has been traditionally assessed by aerobiological spore counts, although this does not always offer an accurate estimate of airborne allergen load. This study aims to pinpoint the key factors that explain the presence and variation of Alt a 1 concentration in the atmosphere in order to establish exposure risk periods and improve forecasting models. Alternaria spores were sampled using a Hirst-type volumetric sampler over a five-year period. The allergenic fraction from the bioaerosol was collected using a low-volume cyclone sampler and Alt a 1 quantified by Enzyme-Linked ImmunoSorbent Assay. A cluster analysis was executed in order to group days with similar environmental features and then analyze days with the presence of the allergen in each of them. Subsequently, a quadratic discriminant analysis was performed to evaluate if the selected variables can predict days with high Alt a 1 load. The results indicate that higher temperatures and absolute humidity favor the presence of Alt a 1 in the atmosphere, while time of precipitation is related to days without allergen. Moreover, using the selected parameters, the quadratic discriminant analysis to predict days with allergen showed an accuracy rate between 67 % and 85 %. The mismatch between daily airborne concentration of Alternaria spores and allergen load can be explained by the greater contribution of medium-to-long distance transport of the allergen from the major emission sources as compared with spores. Results highlight the importance of conducting aeroallergen quantification studies together with spore counts to improve the forecasting models of allergy risk, especially for fungal spores.

This study considers the relationship between the risk of hospital admission due to respiratory diseases, the daily weather, and the air pollution conditions between 2000 and 2006. A synoptic climatological approach is used to investigate the links between weather types and all hospital admissions due to respiratory diseases in Castilla-La Mancha (CLM), Spain. The main circulation weather types (CWTs) were determined for winter and spring, the seasons with the highest percentage of hospital admissions, and the frequency distribution of these types was also analyzed. The study includes a summary of the main characteristics of the hospital admission series and their distribution over the study period of seven years, as well as the frequency distributions of the admissions classified by gender and age, for each season, month and day of the week. In addition, an admission index was used to compare CWTs and hospital admissions due to respiratory diseases. The results show distinctly different responses of daily respiratory disease admission rates (RD) to the eight CWTs identified in winter and in spring. In winter, three CWTs (southwesterly (SW), anticyclonic (A) and hybrid anticyclonic southwesterly (HASW)) present values 1.5 times above the average admission rates. In contrast, there are no significant differences in spring. Finally, the results of Principal Component Analysis applied to the daily series of meteorological parameters, atmospheric pollutants and morbidity data revealed that in winter the decrease in RD is related to increases in temperature and pressure. These results represent an important step in identifying reliable connections between weather-air pollutants and human health.

Alternaria genus contains more than 300 ubiquitous fungal species, and thus its spores can be found in both outdoor and indoor environments. Many species of this genus are catalogued as plant pathogens that affect different crops, causing important losses in the agricultural sector. Moreover, Alternaria spores have also been described as a significant source of allergens, with Alt a 1 glycoprotein being the major allergen. This allergen reacts with over 90% of IgE serum in patients sensitized to Alternaria and can be present in the air even low airborne spore concentrations. Traditionally, forecasting models for risk periods associated with environmental exposition to this fungus have been based only on aerobiological spore counts combined with some meteorological factors such as temperature and precipitation. However, other parameters such as land use and prevailing winds also significantly influence the airborne allergen load. For that reason, the aim of this study is to identify the major emission sources of Alternaria spores and Alt a 1 allergen to improve the forecasting models of environmental exposure to this aeroallergen. This study was carried out in León (Spain) over a five-year period (2016-2020). Airborne spores were sampled using a Hirst-type volumetric sampler, following the methodology proposed by CEN legislation EN 16868:2019. The samples were analysed under a light microscope at 400x magnification using two longitudinal transects in the effective collecting area. Furthermore, the allergenic fraction was collected by a cyclone low-volume sampler and the major allergen Alt a 1 was quantified by ELISA on daily samples The land use data within a 30 km radius of monitoring station were obtained from Castilla y León crops and natural maps, which use satellite imagery from the Copernicus programme with a spatial resolution of 10 m. Additionally, wind parameters, in combination with spore and allergen concentration, were analyzed using conditional probability functions plots. The results show that areas covered by cereal crops or pastures act as the major sources of Alternaria conidia and Alt a 1 allergen. However, there are discrepancies between the airborne transport of spores and allergen since the highest mean spore concentration values occurs with wind speed from 1 to 2 m s -1; whereas wind speed between 2 and 4 m s-1 favor the highest Alt a 1 allergen concentrations. This may indicate a greater contribution of long-medium transport of allergen than spores, highlighting the need to perform aerobiological spore counts in combination with allergen quantification for a better assessment of atmospheric allergenic load. Finally, this also underscores the importance of considering the land cover and the location of emission sources, as well as the main atmospheric transport routes, to improve the risk forecasting models for environmental exposure to this aeroallergen.

In July 2012, an indoor/outdoor monitoring programme was undertaken in two university sports facilities: a fronton and a gymnasium. Comfort parameters (temperature, relative humidity, and CO2), CO and total volatile organic compounds (TVOCs) were continuously monitored. Concentrations of NO2, carbonyl compounds and individual VOCs were obtained, after passive sampling, by spectrophotometry, high-performance liquid chromatography and gas chromatography with flame ionisation detection, respectively. Low volume samplers were used to collect particulate matter (PM10). During the occupancy periods, the relative humidity values were within the comfort limits in both buildings, but frequent daytime temperatures over 30°C in the gymnasium make this indoor space rather uncomfortable. The minimum ventilation rates stipulated for acceptable indoor air quality were observed in both sports facilities. It was found that cleaning activities may have a large influence on the VOC levels. Acrolein was one of the most abundant carbonyl compounds, showing concentrations above the recommended limit. Formaldehyde was detected at levels lower than those commonly reported for other indoor environments. In the fronton, the PM10 concentrations obtained during the occupancy periods ranged between 38 and 43 µg/m3. Much higher levels, from 154 to 198 µg/m3, were registered in the gymnasium. Weekend average values lower than 20 µg/m3 were obtained in both sports facilities, which are comparable to the outdoor levels throughout the week. The high particle levels in the gym are mainly due to the climbing chalk and the constant process of resuspension.

This study focuses on the analysis of the distribution, both spatial and temporal, of the PM10 (particulate matter with a diameter of 10 µm or less) concentrations recorded in nine EMEP (European Monitoring and Evaluation Programme) background stations distributed throughout mainland Spain between 2001 and 2019. A study of hierarchical clusters was used to classify the stations into three main groups with similarities in yearly concentrations: GC (coastal location), GNC (north–central location), and GSE (southeastern location). The highest PM10 concentrations were registered in summer. Annual evolution showed statistically significant decreasing trends in PM10 concentration in all the stations covering a range from −0.21 to −0.50 µg m−3/year for Barcarrota and Víznar, respectively. Through the Lamb classification, the weather types were defined during the study period, and those associated with high levels of pollution were identified. Finally, the values exceeding the limits established by the legislation were analyzed for every station assessed in the study.

Domestic chores are an important part of the household's daily routine and can contribute significantly to personal exposure. In this study, the particulate mass and number concentrations were assessed when using two irons (steam iron and steam iron with boiler) under distinct conditions (minimum ventilation and indoor doors open) and in the background air. The detailed PM10 chemical characterisation included organic and elemental carbon, elements and organic speciation. Particle number emission rates ranged from 8.1 +/- 0.09 x 10(11) to 15 +/- 3.5 x 10(11) particles min(-1). Ratios of peak to background levels indicate that ironing can elevate the ultrafine particle number concentrations by a factor ranging from 35 to 194. PM10 emission rates from steam iron, under minimum ventilation conditions (6.6 +/- 1.4 mu g s(-1)), were higher than those from steam iron with the doors open (1.9 +/- 1.6 mu g s(-1)). The highest particle number and mass emission rates were recorded when the steam iron with boiler was used. Regarding the chemical composition of particles, elemental carbon and strontium were only detected during ironing. Bromide concentrations increased noticeably over background levels (9-51 times) during ironing. PM10 samples encompassed a wide range of organic compounds, part of which can be attributed to the handling of textiles and the use of detergents, fabric softeners, cosmetics and personal care products. Substances emitted by volatilisation or shedding of textile fibres, or due to handling, can contribute to human exposure through inhalation. The cancer risks associated with inhalation of metals and PAH were found to be negligible.

Bioaerosols play a major role in the plant life of ecosystems. In addition, they have a profound impact on human health, since they may cause lung diseases or allergies. The key objective of this study is to assess the below cloud scavenging effect of rainfall on pollen concentration. The analysis is based on a sampling carried out in León, Spain, between 2015 and 2018. The rainfall variables and the pollen concentrations have been obtained with a disdrometer and a volumetric Hirst type spore-trap, respectively. In order to evaluate the scavenging, three parameters have been calculated: scavenging efficiency (through the concentration-weighted average (%ΔC)), the scavenging coefficient (λ) and the percentage of events with a decrease in pollen concentration (%ES) also called events with effective scavenging. 71% of rain events presented an effective scavenging that affected all types of pollen. The %ΔC mean value of total pollen was 24 ± 18% (positive values indicate an effective scavenging) and the types of pollen with the highest values were Castanea and Cupressaceae (71 and 40%, respectively). A linear model (R2 = 0.94) to estimate the pollen concentration after rain was built with variables such as pollen concentration before rain and other variables from a weather station and a disdrometer. Furthermore, we have shown the possibility of knowing in real time the probable Cupressaceae pollen concentration, from the initial pollen concentration and the physical parameters of rain (such as raindrop size, rain intensity or volume swept by raindrops in their falling path).

Terraces are a common Mediterranean feature influencing soils, slopes and subsurface hydrology; however, little is known about their impact on erosion processes, especially in humid regions. The purpose of this study was to assess how terracing after a fire affected erosion processes such as splash erosion. For 8 months, the study monitored splash erosion in three terraced plots, one plot under pre-fire conditions and the other two under post-fire conditions. Assessment of the impact of the terracing treatment in such plots was carried out by the installation of two different splash erosion quantitative systems: cups and funnels. An analysis of the splash data obtained in 17 rainfall events and meteorological data collected during each one of those periods was then performed. A significant positive correlation between the amount of rainfall and the splash erosion was observed. The two splash sampling systems show a high degree of concordance; however, the funnel-type model seems to be the most appropriate when it comes to preventing loss of splashed soil samples. The post-fire treatment with terracing leads to a smaller stability of surface soil aggregates, causing higher splash erosion rates. Sampling using the funnel system collects three times the amount of splashed soil than that collected by the cup system, although both systems correlate appropriately with the meteorological parameters.

A one-year aerosol sampling campaign, between 2016 and 2017, was conducted in a suburban area of León city, Spain. An association between the Positive Matrix Factorization (PMF) results and air masses through circulation weather types was carried out, through the construction of linear models from the PM10 concentrations and its chemical composition. The aerosol sources, identified by PMF six-factor solution, were: traffic (29%), aged sea salt (26%), secondary aerosols (16%), dust (13%), marine aerosol (7%) and biomass burning (3%). Traffic and secondary factors showed the highest PM10 contribution in the hybrid cyclonic types with wind component from the first and second quadrant. Anticyclonic types with wind component from the first quadrant exhibited high values of secondary, aged sea salt and dust factors. The highest contributions of the dust factor were also associated with northerly types. The linear models built for estimating the source apportionment of PM10, from aerosol chemical composition and geostrophic flow, showed positive coefficients for: westerly flows (WF) in marine factor, southerly flows (SF) in secondary and traffic factors, and shear southerly vorticities (ZS) in dust factor. Negative dependences were observed for ZS in aged sea salt factor and for SF in dust factor. The PM10 mass concentration calculated by the linear models and by the PMF model were strongly correlated. This can be very useful to determine the contribution of a specific source to PM10 in León, only by knowing some meteorological and chemical variables.

Beauty salons are considered occupational environments where the staff personnel and clients are exposed to high levels of airborne pollutants. In this study, air quality monitoring was carried out in Le ' on, Spain. Temperature, relative humidity, CO2, CO and particulate matter were continuously monitored inside and outside areas of the salon. PM10 was simultaneously collected onto filters. Volatile organic compounds and carbonyls were sampled inside the salon. Indoor PM10 concentrations exceeded the recommended 24-h guideline of 50 mu g m-3. A detailed PM10 chemical characterisation included organic and elemental carbon, trace elements, watersoluble ions and organic speciation. Indoor vs outdoor ratios of PM10, as well as the majority of PM10-bound organic compounds, were >1. During work periods, organic carbon accounted for 29.5 +/- 1.8 and 16.2 +/- 4.5 % wt. of PM10 indoors and outdoors, respectively. More than 200 individual organic compounds were detected in the PM10, including aliphatic alcohols, fatty acids, phthalates, glycerol derivatives, fatty acid alkyl esters, phenolic compounds, alkanes and polycyclic aromatic hydrocarbons, among others. Many of them are part of formulations widely used in hair cosmetics, personal care and cleaning products. Inadequate ventilation, working activities and the use of specific products can greatly contribute to high indoor levels of organic air pollutants. Formaldehyde revealed a cancer risk of 4.6 x 10-6, higher than the guideline level, suggesting a "possible risk" for workers. The total excess lifetime cancer risk from exposure to multiple compounds was 9.3 x 10-6, which is lower than the acceptable risk, but not negligible.

Vacuum cleaning can be a household source of particulate matter (PM) both from the vacuum motor and from settled dust resuspension. Despite the evidence of this contribution to PM levels indoors, the effect of this source on PM composition is still unknown. In this study, four vacuum cleaners (washable filter bag less, wet, bagged and HEPA filter equipped robot) were tested for the emission rate of particulate mass and number. The detailed PM chemical characterisation included organic and elemental carbon, metals and organic speciation. PM10 emission rates from bagged vacuum operation were much higher (207 +/- 99.0 mu g min(-1)) compared with the ones obtained from wet (86.1 +/- 16.9 mu g min(-1)) and washable filter bag less vacuums (75.4 +/- 7.89 mu g min(-1)). Particle (8-322 nm) number emission rates ranged from 5.29 x 10(11) (washable filter bag less vacuum) to 21.2 x 10(11) (wet vacuum) particles min(-1). Ratios of peak to background levels indicate that vacuuming can elevate the ultrafine particle number concentrations by a factor ranging from 4 to 61. No increase in PM mass or number concentrations was observed during the HEPA filter equipped vacuum operation. The increase in copper and elemental carbon PM10 contents during vacuuming suggested motor emissions. Organic compounds in PM10 included alkanes, PAHs, saccharides, phenolics, alcohols, acids, among others. However, it was not possible to establish a relationship between these compounds and vacuuming due to the vast array of possible household sources. The cancer risks associated with metals and PAH inhalation were negligible.

This paper compares two different geographical sites, Aveiro and León, from different climatic regions, oceanic and continental, but which share the same type of weather (according to Lamb’s classification). The analysis was carried out over one year, and has revealed that rainfall in Aveiro is heavier and more abundant, with a higher number of raindrops and a longer duration of rain events (on average, 10 min longer than in Leon). Mean raindrop size is 0.45 mm in Aveiro and slightly smaller (0.37 mm) in Leon; in addition, the kinetic energy and linear momentum values in Aveiro are three times higher than those in Leon. A comparison of raindrop size distributions by weather type has shown that for both locations westerly weather presented a higher probability of rainfall, and the gamma distribution parameters for each weather type were independent of the study zone. When the analysis is done for the characteristics of rain related with erosion, the westerly cyclonic weather types (cyclonic west (CW) and cyclonic south-westerly (CSW)) are among the most energetic ones in both locations. However, comparing their five weather types with higher kinetic energy, in Aveiro a westerly component implies higher kinetic energy, while in Leon a southerly component involves more energy in the rain.

A substantial fraction of the atmospheric aerosols originates from secondary new particle formation (NPF), where atmospheric vapours are transformed into particles that subsequently grow to larger sizes, affecting human health and the climate. In this study, we investigate aerosol size distributions at two stations located close to each other (∼ 20 km) but at different altitudes: urban (UGR; 680 m a.s.l., metres above sea level) and high-altitude remote (SNS; 2500 m a.s.l.) sites, both in the area of Granada, Spain, and part of AGORA observatory (Andalusian Global ObseRvatory of the Atmosphere). The analysis shows a significant contribution of nucleation mode aerosol particles to the total aerosol number concentration at both sites, with a contribution of 47 % and 48 % at SNS and UGR, respectively. Due to the important contribution of NPF events to the total aerosol number concentrations and their high occurrence frequency (> 70 %) during the study period, a detailed analysis of NPF events is done in order to get insight into the possible mechanisms and processes involved in NPF events at these contrastive sites. At SNS, NPF is found to be associated with the transport of gaseous precursors from lower altitudes by orographic buoyant upward flows. NPF events at the SNS site are always observed from the smallest measured sizes of the aerosol size distribution (4 nm), implying that NPF takes place in or in the vicinity of the high-altitude SNS station rather than being transported from lower altitudes. Although NPF events at the mountain site seem to be connected with those occurring at the urban site, growth rates (GRs) at SNS are higher than those at the UGR site (GR7−25 of 6.9 and 4.5 nm h−1 and GR4−7 of 4.1 and 3.6 nm h−1 at SNS and UGR, respectively). This fact could have special importance for the production of cloud condensation nuclei (CCN) and therefore for cloud formations which may affect regional/global climate, since larger GRs at mountain sites could translate to a larger survival probability of NPF particles reaching CCN sizes, due to the shorter time period needed for the growth. The analysis of sulfuric acid (H2SO4) shows that the contribution of H2SO4 is able to explain a minimal fraction contribution to the observed GRs at both sites (< 1 % and < 10 % for the 7–25 and 4–7 nm size ranges, respectively), indicating that other condensing vapours are responsible for the majority of particle growth, as well as the differing growth rates between the two sites. Results also show that the condensation sink (CS) does not play a relevant role in NPF processes at both sites and points to the availability of volatile organic compounds (VOCs) as one of the main factors controlling the NPF events at both sites. Finally, a closer analysis of the NPF events that were observed at the SNS site during a Saharan dust episode that occurred during the field campaign was carried out, evidencing the role of TiO2 and F2O3 together with VOCs in promoting new particle formation during this dust intrusion event. Although further investigation is needed to improve our understanding in this topic, this result suggests that climate effects of mineral dust and NPF are not disconnected from each other as it was commonly thought. Therefore, since mineral dust contributes to a major fraction of the global aerosol mass load, dust–NPF interaction should be taken into account in global aerosol-climate modelling for better climate change prediction.