HEPA filters of portable air cleaners as a tool for the surveillance of SARS-CoV-2.

Studies about the identification of SARS-CoV-2 in indoor aerosols have been conducted in hospital patient rooms and to a lesser extent in nonhealthcare environments. In these studies, people were already infected with SARS-CoV-2. However, in the present study, we investigated the presence of SARS-CoV-2 in HEPA filters housed in portable air cleaners (PACs) located in places with apparently healthy people to prevent possible outbreaks. A method for detecting the presence of SARS-CoV-2 RNA in HEPA filters was developed and validated. The study was conducted for 13 weeks in three indoor environments: school, nursery, and a household of a social health center, all in Ciudad Real, Spain. The environmental monitoring of the presence of SARS-CoV-2 was conducted in HEPA filters and other surfaces of these indoor spaces for a selective screening in asymptomatic population groups. The objective was to limit outbreaks at an early stage. One HEPA filter tested positive in the social health center. After analysis by RT-PCR of SARS-CoV-2 in residents and healthcare workers, one worker tested positive. Therefore, this study provides direct evidence of virus-containing aerosols trapped in HEPA filters and the possibility of using these PACs for environmental monitoring of SARS-CoV-2 while they remove airborne aerosols and trap the virus.

Assessment of CO2 and aerosol (PM2.5, PM10, UFP) concentrations during the reopening of schools in the COVID-19 pandemic: The case of a metropolitan area in Central-Southern Spain.

Public health authorities have been paramount in guaranteeing that adequate fresh air ventilation is promoted in classrooms to avoid SARS-CoV-2 transmission in educational environments. In this work it was aimed to assess ventilation conditions (carbon dioxide, CO2) and suspended particulate matter (PM2.5, PM10 and UFP) levels in 19 classrooms - including preschool, primary and secondary education - located in the metropolitan area of Ciudad Real, Central-Southern Spain, during the school's reopening (from September 30th until October 27th, 2020) after about 7 months of lockdown due to COVID-19 pandemic. The classrooms that presented the worst indoor environmental conditions, according to the highest peak of concentration obtained, were particularly explored to identify the possible influencing factors and respective opportunities for improvement. Briefly, findings suggested that although ventilation promoted through opening windows and doors according to official recommendations is guaranteeing adequate ventilation conditions in most of the studied classrooms, thus minimizing the risk of SARS-CoV-2 airborne transmission, a total of 5 (26%) surveyed classrooms were found to exceed the recommended CO2 concentration limit value (700 ppm). In general, preschool rooms were the educational environments that registered better ventilation conditions, while secondary classrooms exhibited the highest peak and average CO2 concentrations. In turn, for PM2.5, PM10 and UFP, the concentrations assessed in preschools were, on average about 2-fold greater than the levels obtained in both primary and secondary classrooms. In fact, the indoor PM2.5 and PM10 concentrations substantially exceeded the recommended limits of 8hr-exposure, established by WHO, in 63% and 32% of the surveyed classrooms, respectively. Overall, it is expected that the findings presented in this study will assist the establishment of evidence-based measures (namely based on ensuring proper ventilation rates and air filtration) to mitigate preventable environmental harm in public school buildings, mainly at local and national levels.

A preliminary study on ambient levels of carbonyls, benzene, toluene and xylene in the south-west of the Iberian Peninsula (Huelva coast), Spain.

We report the first observations of volatile organic compound (VOC) concentrations, including aldehydes, in the coastal, industrial area of Huelva near the Doñana National Park (south-west of the Iberian Peninsula). The periods studied were July-September 2008 and February-November 2009. Formaldehyde, acetaldehyde, acetone, propanal, benzene, toluene and m/p-xylenes were identified and quantified. Acetone and formaldehyde were the most abundant carbonyls, followed by acetaldehyde and propanal. Maximum and minimum values for all these compounds in the period of measurement, and their relationship with meteorological parameters or influence of anthropogenic or biogenic emissions, are analysed. Finally, different concentration ratios and correlations were calculated to assess the effect of the anthropogenic or biogenic processes on the observed VOC levels.

Assessment of atmospheric levels of carbonyls in an urban environment of Argentina.

It is well-documented that carbonyl compounds have adverse effects on human health. On the other hand, these oxygenated volatile organic compounds (OVOCs) are precursors of secondary pollutants such as tropospheric ozone or peroxy acetyl nitrate (PAN). In particular, formaldehyde, the simplest carbonyl, is the most abundant carbonyl in the air generated from the degradation of most volatile organic compounds (VOCs). This work presents for the first time the characterization and determination of levels of carbonyl compounds by passive monitoring performed from April-December 2021 in the city of Córdoba, Argentina, the second most populated Mediterranean city located in the center of the country. Annual concentrations, considering the 11 carbonyls measured, were in the range of 0.13-8.75 µgm-3. Formaldehyde and acetaldehyde were the carbonyls detected in the highest annual average concentrations of 4.44 ± 1.75 µgm-3 and 3.85 ± 1.44 µgm-3, respectively. These carbonyls represent a contribution of around 40-57% on total carbonyls measured. Statistical analysis to determine significant differences and Pearson correlations with the meteorological parameters were performed. Spring and summer were found to be the seasons with the highest carbonyl concentration linked to forest fire episodes, especially in springtime. The values for the C1/C2 and C2/C3 ratios showed that sources of carbonyl formation are anthropogenic. In addition, the prop-Equiv concentration was determined, where formaldehyde and acetaldehyde were the main producers of tropospheric ozone. The ozone formation potential (OFP) showed that spring and summer are the seasons where carbonyls contribute to the formation of tropospheric ozone.This study represents a first approach of the carbonyl concentration in the city and of the influence of meteorological parameters on the behavior of carbonyls.

Preliminary characterization of polycyclic aromatic hydrocarbons, nitrated polycyclic aromatic hydrocarbons and polychlorinated dibenzo-p-dioxins and furans in atmospheric PM10 of an urban and a remote area of Chile.

The composition of particulate organic fraction was determined in atmospheric aerosols emitted in two sites of central and southern Chile. In particular, polycyclic aromatic hydrocarbons (PAHs), nitrated-PAHs (N-PAHs) and polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs) were investigated in both the urban site of Concepcion and the remote site of Coyhaique. The sampling was carried out with an active device during March and April 2007, and organic compounds adsorbed in air particles, having an aerodynamic diameter lower than 10 microm (PM10), were characterized using gas chromatography coupled with mass spectrometric detection (GC-MS). Aerosol contents varied from 0.004 to 3.4 ng m(-3) for PAH, from 0.007 to 3.5 pg m(-3) for N-PAH, from 0.002 to 355.7 fg Nm(-3) for PCDDs and from 0.04 to 15 fg Nm(-3) for PCDFs. As expected, the lowest values were found in the remote area. In Concepcion city, despite the low number of samples, PAH levels and diagnostic ratios of some marker compounds suggested the diesel emissions, probably coming from trucks, as the major source of particulate organic pollutants associated with direct emission. Another important source of atmospheric pollution in the urban site was likely represented by the steel industry existing in this area, outlined both by the analysis of PAH and PCDD/F levels. In the samples collected in the remote air of Coyhaique (located in the southern part of Chile), the concentration of pollutants characterized by a long lifetime, as PCDD/Fs, could be related to long-range transport phenomena, instead of local sources.

Formaldehyde, acrolein and other carbonyls in dwellings of university students. Levels and source characterization.

Fifteen carbonyl compounds were investigated in the living rooms and bedrooms of 25 university student flats in the urban area of Ciudad Real (Central Southern Spain) in wintertime. Carbonyls were sampled using Radiello ® passive samplers refilled in the laboratory according to the method described in ISO 16000-3 Standard. The most abundant carbonyls in the living rooms and bedrooms were formaldehyde, acetone, acetaldehyde, hexaldehyde and butyraldehyde. The median concentration levels in the living rooms and bedrooms were: 28.6 and 34.2 µg m-3 for formaldehyde, 18.3 and 23.1 µg m-3 for acetone, 14.3 and 15.8 µg m-3 for acetaldehyde, 11.4 and 14.1 µg m-3 for hexaldehyde and 10.8 and 12.4 µg m-3 for butyraldehyde. The median concentration of formaldehyde, benzaldehyde, valeraldehyde and hexaldehyde was significantly higher in the bedrooms than in the living rooms. Indoor concentrations were significantly higher than outdoor concentrations for all carbonyl measured, indicating that sources in the indoor environment are prevailing in all flats. Principal component analysis, multiple linear regressions and Spearman correlation coefficients were used to investigate the origin, the indoor pollutants determinants and to establish common sources between carbonyls. Eight components were extracted from the application of PCA to the indoor and outdoor measurements accounting for 97.7% of the total variance. Formaldehyde, acetone, acetaldehyde and acrolein presented different indoor sources. In the multiple linear regression analysis, higher formaldehyde concentrations were found in those living rooms with wood floor and smoking was positively associated to acetone, propionaldehyde, benzaldehyde and isovaleraldehyde. Formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde and benzaldehyde concentrations were compared with relevant international guidelines, being their concentrations below recommended values except acrolein, where all measured flats exceeded the reference levels; it would be important to focus on the characterization of emission sources of acrolein in indoor air in order to minimise the exposure and health risk.

Investigation of PAHs, nitrated PAHs and oxygenated PAHs in PM10 urban aerosols. A comprehensive data analysis.

Polycyclic aromatic compounds (PACs) in particulate matter contribute considerably to the health risk of air pollution. As such, we have optimized a method to determine the levels of polycyclic aromatic hydrocarbons, especially nitrated and oxygenated polycyclic aromatic hydrocarbons, in samples of PM10 particulate matter using microwave-assisted extraction (MAE) and gas chromatography coupled to a triple quadrupole mass spectrometer (GC-MS/MS). The proposed method was applied to the analysis of real samples collected in the urban area of Ciudad Real (Spain) during one year. The median total concentrations of eighteen PAHs (∑PAHs) and seven OPAHs (∑OPAHs) were 0.54 and 0.23 ng m-3, respectively, with the corresponding value for NPAH (∑NPAHs) being 0.03 ng m-3 (only detected in 40% of samples). A clear seasonal trend was observed, with higher levels in the cold season and lower in the warm season for ∑PAHs. The same effect was observed for ∑OPAHs, which exhibited a median concentration of 0.72 ng m-3 in the cold season and 0.10 ng m-3 in the warm season, and for ∑NPAH, which exhibited a median of 0.04 ng m-3 in the cold season but were not detected in the warm season. Molecular diagnostic ratios and PCA (principal component analysis) showed a predominantly traffic origin for PACs. The sources of PAHs also depend on meteorological conditions and/or atmospheric reactions, as confirmed by means of statistical analysis. The ∑OPAH/∑PAH and ∑NPAH/∑PAH ratios were higher in the cold season than the warm season, thus suggesting that PAH derivatives originated from primary combustion emission sources together with their parent PAHs. The concentration range found for benzo(a)pyrene was 0.006-0.542 ng m-3, which is below the threshold value of 1 ng m-3 established in European legislation as the annual average value. The lifetime lung risk from inhalation of PM10-bound PACs was estimated to be six cancer cases per million people using the World Health Organization method.

Good and bad get together: Inactivation of SARS-CoV-2 in particulate matter pollution from different fuels.

Air pollution and associated particulate matter (PM) affect environmental and human health worldwide. The intense vehicle usage and the high population density in urban areas are the main causes of this public health impact. Epidemiological studies have provided evidence on the effect of air pollution on airborne SARS-CoV-2 transmission and COVID-19 disease prevalence and symptomatology. However, the causal relationship between air pollution and COVID-19 is still under investigation. Based on these results, the question addressed in this study was how long SARS-CoV-2 survives on the surface of PM from different origin to evaluate the relationship between fuel and atmospheric pollution and virus transmission risk. The persistence and viability of SARS-CoV-2 virus was characterized in 5 engine exhaust PM and 4 samples of atmospheric PM10. The results showed that SARS-CoV-2 remains on the surface of PM10 from air pollutants but interaction with engine exhaust PM inactivates the virus. Consequently, atmospheric PM10 levels may increase SARS-CoV-2 transmission risk thus supporting a causal relationship between these factors. Furthermore, the relationship of pollution PM and particularly engine exhaust PM with virus transmission risk and COVID-19 is also affected by the impact of these pollutants on host oxidative stress and immunity. Therefore, although fuel PM inactivates SARS-CoV-2, the conclusion of the study is that both atmospheric and engine exhaust PM negatively impact human health with implications for COVID-19 and other diseases.

Atmospheric degradation of 3-ethoxy-1-propanol by reactions with Cl, OH and NO3.

An experimental kinetic and mechanistic study of the reactions of 3-ethoxy-1-propanol (CH3CH2OCH2CH2CH2OH) with Cl atoms and OH and NO3 radicals has been carried out at room temperature and atmospheric pressure. FTIR (Fourier Transform Infrared Spectroscopy) and GC-MS (Gas Chromatography/Mass Spectrometry) were used as detection techniques. The rate coefficients were measured with a relative method (units cm3 molecule-1 s-1): (3.46 ± 0.22) × 10-10, (3.48 ± 0.19) × 10-11 and (1.08 ± 0.07) × 10-14 for Cl, OH and NO3 reactions, respectively. Qualitative and quantitative products analysis was carried out and formaldehyde, ethyl formate, ethyl 3-hydroxypropanoate and nitrated compounds were positively identified. A reaction mechanism has been proposed which involves attack by the oxidant at the methylene group in the α-position to an oxygen atom of the ether or alcohol groups, followed by the subsequent reactions of the resulting radicals. The tropospheric reactivity of 3-ethoxy-1-propanol (3E1P) has been compared with the reactivity of other hydroxy ethers to extend our knowledge of this type of compound. The atmospheric implications for 3E1P have been established by estimating parameters such as lifetimes, global warming potential (GWP) and the Photochemical Ozone Creation Potential (POCPE). According to the calculated tropospheric lifetimes, the dominant loss process of 3E1P is its daytime reaction with the OH radical and this has an impact on a local scale.

Indoor and outdoor air concentrations of volatile organic compounds and NO2 in schools of urban, industrial and rural areas in Central-Southern Spain.

Thirty two VOCs including alkanes, aromatic hydrocarbons, terpenes and carbonyl compounds together with NO2 were investigated in a kindergarten classroom, a primary classroom and the playground in 18 schools located in rural areas, an urban area (Ciudad Real) and an industrial area (Puertollano) in the province of Ciudad Real in central southern Spain. The most abundant pollutants at schools were the aldehydes formaldehyde and hexanal. After carbonyls, n-dodecane was the most abundant compound in the study areas. The NO2 concentrations were higher in the urban area, followed by industrial area and rural areas. For benzene, its concentration in the industrial area was significantly higher than in the urban and rural areas which reflects the magnitude of the contribution to the indoor air by petrochemical plant during the sampling period. Principal component analysis, indoor/outdoor ratios, multiple linear regressions and Spearman correlation coefficients were used to investigate the origin, the indoor pollutant determinants and to establish common sources between VOCs and NO2. Seven components were extracted from the application of PCA to the indoor measurements accounting for 77.5% of the total variance. The analysis of indoor/outdoor ratios and correlations demonstrated that sources in the indoor environment are prevailing for most of the investigated VOCs. Benzene and n-pentane have a major relevance as outdoor sources, while aldehydes, terpenes, alkanes and most aromatic hydrocarbons as indoor sources. For NO2, ethylbenzene and toluene both indoor and outdoor sources probably contributed to the measured concentrations. Finally, the results reported in this paper demonstrate that during the measuring period there were not great differences in the indoor air quality of the schools of the three study areas.

Ambient levels of volatile organic compounds and criteria pollutants in the most industrialized area of central Iberian Peninsula: intercomparison with an urban site.

This work presents observations of volatile organic compounds (VOCs), including carbonyls, particulate matter 2.5 (PM2.5) (included in the most recent ambient air quality standards because of its harmful effect on health), PM10 and other important pollutants, CO, SO2, NOx and ozone, over the most industrialized area in the central Iberian Peninsula. Nearly two years of data obtained through a mobile laboratory are used for this purpose. Different concentration ratios and correlations were calculated to assess the effect of the anthropogenic or biogenic processes on the observed VOC levels. The diurnal profile for SO2 is different in Puertollano and it does not coincide with the maxima of the other primary pollutants such as benzene, toluene and xylenes (BTX), CO and NO. This behaviour could be attributed to the fact that SO2 mainly comes from industrial activities. However, an impact of the industry on air quality was detected not only by the results obtained for SO2, but also by the toluene/benzene, T/B, ratio (7.5). Finally, correlations between meteorological conditions and pollution distribution have been considered; also, the analysis of the back trajectories together with Spearman correlation coefficients have been carried out to understand the origin and pathway in some events with unusual high pollutant values.

Characterization of particulate polycyclic aromatic hydrocarbons in an urban atmosphere of central-southern Spain.

Over 1-year period, 13 polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter PM10 have been monitored for the first time in the atmosphere of Ciudad Real, situated at the central-southern Spain. PM10-bound PAHs were collected using a high-volume sampler from autumn 2012 to summer 2013 and were analyzed by HPLC with fluorescence detector. The most abundant PAHs were pyrene, chrysene, benzo[b]fluoranthene, dibenzo[a,h]anthracene and benzo[g,h,i]perylene. The ∑PAH concentrations in Ciudad Real were 888, 368, 259 and 382 pg m(-3) for winter, spring, summer and autumn seasons, respectively. The diurnal variation of PAH was also investigated presenting the highest concentrations during the evening (19:00-23:00). Benzo[a]pyrene concentrations ranged from 2.4 to 110 pg m(-3), these values are lower than the target value proposed by the European legislation, 1 ng m(-3). Diagnostic ratios were used to identify potential sources of PAHs. Results suggest that vehicle emissions are the major source of identified PAHs, with a higher contribution of diesel engines although other anthropogenic sources could also have an impact on the PAH levels.

Levels and sources of volatile organic compounds including carbonyls in indoor air of homes of Puertollano, the most industrialized city in central Iberian Peninsula. Estimation of health risk.

Twenty nine organic air pollutants including carbonyl compounds, alkanes, aromatic hydrocarbons and terpenes were measured in the indoor environment of different houses together with the corresponding outdoor measurements in Puertollano, the most industrialized city in central Iberian Peninsula. VOCs were sampled during 8 weeks using Radiello(®) passive samplers, and a questionnaire on potential VOCs sources was filled out by the occupants. The results show that formaldehyde and hexanal was the most abundant VOCs measured in indoor air, with a median concentration of 55.5 and 46.4µgm(-3), respectively followed by butanal (29.1µgm(-3)), acetone (28.4µgm(-3)) and acetaldehyde (21.4µgm(-3)). After carbonyls, n-dodecane (13.1µgm(-3)) and terpenes (α-pinene, 13.4µgm(-3) and limonene, 13.4µgm(-3)) were the compounds with higher median concentrations. The indoor/outdoor (I/O) ratios demonstrated that sources in the indoor environment are prevailing for most of the investigated VOCs especially for limonene, α-pinene, hexanal, formaldehyde, pentanal, acetaldehyde, o-xylene, n-dodecane and acetone with I/O ratio >6. Multiple linear regressions were applied to investigate the indoor VOC determinants and Spearman correlation coefficients were used to establish common sources between VOCs. Finally, the lifetime cancer risk associated to formaldehyde, acetaldehyde and benzene exposure was estimated and they varied from 7.8×10(-5) to 4.1×10(-4) for formaldehyde, from 8.6×10(-6) to 3.5×10(-5) for acetaldehyde and from 2.0×10(-6) to 1.5×10(-5) for benzene. For formaldehyde, the attributed risk in most sampled homes was two orders of magnitude higher than the one (10(-6)) proposed as acceptable by risk management bodies.