Tree Species-Dependent Inactivation of Coronaviruses and Enteroviruses on Solid Wood Surfaces.

The ongoing challenge of viral transmission, exemplified by the Covid pandemic and recurrent viral outbreaks, necessitates the exploration of sustainable antiviral solutions. This study investigates the underexplored antiviral potential of wooden surfaces. We evaluated the antiviral efficacy of various wood types, including coniferous and deciduous trees, against enveloped coronaviruses and nonenveloped enteroviruses like coxsackie virus A9. Our findings revealed excellent antiviral activity manifesting already within 10 to 15 min in Scots pine and Norway spruce, particularly against enveloped viruses. In contrast, other hardwoods displayed varied efficacy, with oak showing effectiveness against the enterovirus. This antiviral activity was consistently observed across a spectrum of humidity levels (20 to 90 RH%), while the antiviral efficacy manifested itself more rapidly at 37 °C vs 21 °C. Key to our findings is the chemical composition of these woods. Resin acids and terpenes were prevalent in pine and spruce, correlating with their antiviral performance, while oak's high phenolic content mirrored its efficacy against enterovirus. The pine surface absorbed a higher fraction of the coronavirus in contrast to oak, whereas enteroviruses were not absorbed on those surfaces. Thermal treatment of wood or mixing wood with plastic, such as in wood-plastic composites, strongly compromised the antiviral functionality of wood materials. This study highlights the role of bioactive chemicals in the antiviral action of wood and opens new avenues for employing wood surfaces as a natural and sustainable barrier against viral transmissions.

A Rapid Review of Sociocultural Dimensions in Nigeria's Solid Waste Management Approach.

Against the background of an arguable dearth of scholarship on the sociocultural dimensions of Nigeria's solid waste management strategies and practices, this rapid review searched for evidence in the literature. A rapid evidence review and qualitative meta-summary procedure were implemented to utilize the rigor of systematic literature review that met the timelines and limited funding available for this study. It is more appropriate to identify, extract, and synthesize a mixture of qualitative and/or quantitative empirical evidence in the literature. This rapid review found little substantive evidence of scholarly sociocultural approaches in Nigeria's solid waste management. It also discovered constant factors of inadequate and weak multidisciplinary or non-holistic approaches to driving innovation and effective social impact in Nigeria's solid waste management practices. The results were interpreted vis-à-vis the need to leverage the social sciences, particularly the range and scope of social work practice configurations and possibilities, to scientifically advance and substantially accelerate the implementation of evidence-based policy and practice in Nigeria's solid waste management system. This rapid review concluded that the negative results are due to the insufficient conceptual and theoretical bases for Nigeria's solid waste management strategies and/or practices.

Controlling flour dust exposure by an intervention focused on working methods in Finnish bakeries: a case study in two bakeries.

Objectives. The purpose of this study was to examine the effectiveness of intervention strategies to control mass concentrations and peak exposures of flour dust in two Finnish bakeries. The effect of the intervention on the proportion of various particle size fractions of the total particulate matter was also investigated. Methods. Mass concentrations of flour dust were measured during three working days in a pre-intervention and post-intervention study in both an industrial and a traditional bakery. Gravimetric sampling and real-time measurements were performed. Relevant intervention strategies focused on working methods were planned in collaboration with the managers of the bakeries. Results. The average mass concentration of inhalable flour dust reduced in most of the stationary locations post intervention. The reductions in exposure levels were between 39 and 45%. However, the exposure levels increased 28-55% in the breathing zone. Real-time measurements showed reductions in the peak mass concentrations in the traditional bakery post intervention. In both bakeries, the total particulate matter size fraction consisted predominantly of particles with an aerodynamic diameter lower than 1 µm and greater than 10 µm. Conclusion. Further studies are needed to plan more effective intervention measures supplemented by technical control methods in both bakeries.

The effects of paints and moisture content on the indoor air emissions from pinewood (Pinus sylvestris) boards.

The emissions of volatile organic compounds (VOCs) from building materials may significantly contribute to indoor air pollution, and VOCs have been associated with odor annoyance and adverse health effects. Wood materials together with coatings are commonly used indoors for furniture and large surfaces such as walls, floors, and ceilings. This leads to high surface-to-volume ratios, and therefore, these materials may participate remarkably to the VOC levels of indoor environment. We studied emissions of VOCs and carbonyl compounds from pinewood (Pinus sylvestris) boards of 10% and 16% moisture contents (MC) with three paints using small-scale test chambers (27 L). The emissions from uncoated pinewood and paints (on a glass substrate) were tested as references. The 28-day experiment showed that the VOC emissions from uncoated pinewood were lower from sample with 16% MC. Painted pinewood samples showed lower emissions compared to paints on glass substrate. Additionally, paints on 16% MC pinewood exhibited lower emissions than on drier 10% MC wood. The emissions from painted pinewood samples were dominated by paint-based compounds, but the share of wood-based compounds increased over time. However, we noticed differences between the paints, and wood-based emissions were clearly higher with the most permeable paint.

Weathering of Antibacterial Melt-Spun Polyfilaments Modified by Pine Rosin.

For many antibacterial polymer fibres, especially for those with natural functional additives, the antibacterial response might not last over time. Moreover, the mechanical performance of polymeric fibres degrades significantly during the intended operation, such as usage in textile and industrial filter applications. The degradation process and overall ageing can lead to emitted volatile organic compounds (VOCs). This work focused on the usage of pine rosin as natural antibacterial chemical and analysed the weathering of melt-spun polyethylene (PE) and poly lactic acid (PLA) polyfilaments. A selected copolymer surfactant, as an additional chemical, was studied to better integrate rosin with the molecular structure of the plastics. The results reveal that a high 20 w-% of rosin content can be obtained by surfactant addition in non-oriented PE and PLA melt-spun polyfilaments. According to the VOC analysis, interestingly, the total emissions from the melt-spun PE and PLA fibres were lower for rosin-modified (10 w-%) fibres and when analysed below 60 ℃. The PE fibres of the polyfilaments were found to be clearly more durable in terms of the entire weathering study, i.e., five weeks of ultraviolet radiation, thermal ageing and standard washing. The antibacterial response against Gram-positive Staphylococcus aureus by the rosin-containing fibres was determined to be at the same level (decrease of 3-5 logs cfu/mL) as when using 1.0 w-% of commercial silver-containing antimicrobial. For the PE polyfilaments with rosin (10 w-%), full killing response (decrease of 3-5 logs cfu/mL) remained after four weeks of accelerated ageing at 60 ℃.

Emissions, airflow patterns and modeling of test compounds in controlled hospital environments.

Spreading and distribution of selected volatile organic compounds (VOCs) released as point source emissions in a hospital environment were investigated in two office rooms and two patient rooms. Six tracer compounds were released from six locations and their concentrations were measured in five sampling sites during two consecutive days. The air flow rates, velocity and flow direction, air temperature, pressure differences between adjacent rooms, and relative humidity and concentrations of the tracer compounds were measured. The results revealed that the size of the examined space and ventilation rates, the monitoring point should be either close to the exhaust terminal device or in the middle of the occupied zone the way that supply air flows do not interfere the measurements. Depending on the inlet terminal device and its location, the air is either delivered parallel to the ceiling or it can be directed to a desired spot into the occupied zone. The tracer compounds did spread evenly within the room and their concentrations decreased inversely with the distance. In rooms with a good ventilation, the concentrations at the exhaust air terminal units were close to those measured near the source point. The results obtained from modeling were consistent with the measurements.

The effect of the shoeless course on particle concentrations and dust composition in schools.

Airborne particles may effect on indoor air quality in schools. One significant particle source is outdoor dust and soil transported indoors on people's shoes, which may be resuspended, and further inhaled by pupils and teachers. In many Finnish schools, shoes are taken off by coat racks near the classrooms (shoe schools). The new course of action is to take shoes off right when entering the building (sock schools). In this study, particle mass and number concentrations, together with chemical composition of the dust were investigated in sock and shoe schools. According to results, PM10 and PM15 concentrations in corridors were significantly higher in shoe schools compared to sock schools (p < 0.05). The shoeless course did not affect on the particle number concentrations, but the increases in the number concentrations originated from diners. The elemental concentrations (Li, Al, Si, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, Pb) in settled dust were also higher in shoe schools compared to sock schools, and the Zn concentrations differed significantly (p < 0.05). In conclusion, this study showed that by taking the shoes off when entering the school building you can enhance the indoor air quality by reducing the particle mass concentrations.

Control of Dust Dispersion From an Enclosed Renovation Site Into Adjacent Areas by Using Local Exhaust Ventilation.

OBJECTIVE: In real-world applications, implementation of an enclosure and negative pressurization is not always adequate to prevent the dispersion of dust from renovation sites. This study aimed to quantify the effect of local exhaust ventilation (LEV) in controlling the dust concentration within an enclosed renovation site to reduce the dust dispersion into adjacent areas. METHODS: The concentrations of inhalable and respirable dust were measured in 16 cases during renovation projects. Filter samples and time-resolved dust concentration data were collected simultaneously from the renovation site and adjacent areas to assess the efficacy of LEV in limiting the dust dispersion. RESULTS: The dispersion of dust outside of the enclosed renovation sites was limited significantly with using LEV. The estimated dust removal efficiency of LEV was 79% for inhalable dust concentration in the renovation site and 62% in the adjacent area. The use of LEV reduced the concentration of respirable dust by 33‒90% in the adjacent area and 80-87% within the renovation site. CONCLUSIONS: Using LEV was found to play a substantial role in dust containment, particularly when the enclosure failed to maintain the negative pressure. The study provides data-driven recommendations that are of practical importance as they promote healthier workplaces and policy improvements. In conclusion, dust dispersion into adjacent areas is prevented with an airtight enclosure (including airlocks) and continuous negative pressure. Dust containment was also obtained by having target dust concentration at the enclosed renovation site to below 4 mg m-3 for inhalable dust and below 1 mg m-3 for respirable dust, even though the enclosures not being continuously under negative pressure. The suggested target concentrations are achievable by using on-tool LEV during the most dust-producing tasks.

Indoor air-related symptoms and volatile organic compounds in materials and air in the hospital environment.

In this case study, hospital workers did suffer from symptoms related to the poor indoor air quality. To investigate reasons for symptoms MM40-survey and house inspection methods were performed. The study consisted of 49 operating rooms and 470 employees. MM-40 survey revealed that over 40% of the staff suffered from skin reactions, over 50% had upper respiratory tract symptoms and 25% suffered headaches. No reason for the staff's symptom could be found in the structural studies of workplaces. The mean air exchange rate of the rooms was 5.51/h. In total 61 materials and 49 indoor air samples were taken. The most frequently found compounds in the material samples were 2-ethyl-1-hexanol and aliphatic hydrocarbons. VOC emissions were high in some of the material samples and they presumably were the one reason for the workers' symptoms observed in some in of the rooms. However, indoor air VOC concentrations were low in most of the cases. According to the linear regression model emissions from flooring material couldn't explain the indoor air concentration of the VOCs. One reason for that was the high ventilation rates of the rooms, which presumably kept VOC levels in indoors low. In addition, VOC concentrations indoors were strongly related to the ongoing healthcare activities in the hospital.

The Evaluation of Short-Term Water Misting of Room Air in Reducing Airborne Dust after Renovation Work.

OBJECTIVE: To shorten the time for airborne dust concentration to be reduced to a lower level after a renovation task has been completed, a short-term water misting method was assessed. A short-term water misting method is based on low water consumption to avoid harmful wetting of materials. The method is considered similar to a general ventilation method that dilutes work-generated airborne dust concentrations. Thus, short-term misting is not intended to replace the source control measures. METHODS: Airborne dust removal by the short-term water misting performed after dust generation was evaluated in a controlled laboratory settings by comparing PM10 decay and inhalable dust concentrations between a control and misting tests (average water flow = 0.22 l min-1) of 2 and 4 min. A portable handheld misting device was used. The practicability and effectiveness of the misting technique as a supplementary control measure was verified in the three field cases. RESULTS: In laboratory tests, reductions in airborne PM10 and inhalable dust were 30% and 28%, avoiding condensation of water to surfaces. In the field, inhalable dust concentrations were reduced by 86-95% after an hour from the misting, whereas ventilation alone was calculated to dilute dust concentrations by 18-39%. Average clean air delivery rates varied from 0.03 to 0.07 m3 s-1. CONCLUSIONS: Short-term misting after a dust-generating task is an effective measure to control the airborne dust after dust-producing tasks in environments where an effective air exchange for dust removal is not a feasible alternative. The information obtained from the study is beneficial to construction and renovation project management personnel and field practitioners.

Deposition of respiratory virus pathogens on frequently touched surfaces at airports.

BACKGROUND: International and national travelling has made the rapid spread of infectious diseases possible. Little information is available on the role of major traffic hubs, such as airports, in the transmission of respiratory infections, including seasonal influenza and a pandemic threat. We investigated the presence of respiratory viruses in the passenger environment of a major airport in order to identify risk points and guide measures to minimize transmission. METHODS: Surface and air samples were collected weekly at three different time points during the peak period of seasonal influenza in 2015-16 in Finland. Swabs from surface samples, and air samples were tested by real-time PCR for influenza A and B viruses, respiratory syncytial virus, adenovirus, rhinovirus and coronaviruses (229E, HKU1, NL63 and OC43). RESULTS: Nucleic acid of at least one respiratory virus was detected in 9 out of 90 (10%) surface samples, including: a plastic toy dog in the children's playground (2/3 swabs, 67%); hand-carried luggage trays at the security check area (4/8, 50%); the buttons of the payment terminal at the pharmacy (1/2, 50%); the handrails of stairs (1/7, 14%); and the passenger side desk and divider glass at a passport control point (1/3, 33%). Among the 10 respiratory virus findings at various sites, the viruses identified were: rhinovirus (4/10, 40%, from surfaces); coronavirus (3/10, 30%, from surfaces); adenovirus (2/10, 20%, 1 air sample, 1 surface sample); influenza A (1/10, 10%, surface sample). CONCLUSIONS: Detection of pathogen viral nucleic acids indicates respiratory viral surface contamination at multiple sites associated with high touch rates, and suggests a potential risk in the identified airport sites. Of the surfaces tested, plastic security screening trays appeared to pose the highest potential risk, and handling these is almost inevitable for all embarking passengers.

Production and characterization of bioaerosols for model validation in spacecraft environment.

This study aimed to evaluate the suitability of two bioaerosol generation systems (dry and wet generation) for the aerosolization of microorganisms isolated from the International Space Station, and to calibrate the produced bioaerosols to fulfill the requirements of computational fluid dynamics model (CFD) validation. Concentration, stability, size distribution, agglomeration of generated bioaerosol and deposition of bioaerosols were analyzed. In addition, the dispersion of non-viable particles in the air was studied. Experiments proved that wet generation from microbial suspensions could be used for the production of well-calibrated and stabile bioaerosols for model validation. For the simulation of the natural release of fungal spores, a dry generation method should be used. This study showed that the used CFD model simulated the spread of non-viable particles fairly well. The mathematical deposition model by Lai and Nazaroff could be used to estimate the deposition velocities of bioaerosols on surfaces, although it somewhat underestimated the measured deposition velocities.

Concentrations and number size distribution of fine and nanoparticles in a traditional Finnish bakery.

In bakeries, high concentrations of flour dust can exist and ovens release particles into the air as well. Particle concentrations (mass, number) and number size distribution may vary considerably but the variation is not commonly studied. Furthermore, the role of the smallest size fractions is rarely considered in the exposure assessment due to their small mass. The objectives of this work were to find out how concentrations and number size distribution of fine and nanoparticles vary in a traditional Finnish bakery and to determine the exposure of a dough maker to the nanoparticle fraction of the inhalable dust. Two measurement campaigns were carried out in a traditional, small-scale bakery. Sampling was performed at the breathing zone of the dough maker and three stationary locations: baking area, oven area, and flour depository. Both real-time measurements and conventional gravimetric sampling were conducted. Nanoparticle fraction of the inhalable dust was determined using an IOM sampler with a customized precyclone. Number concentration of fine and nanoparticles, and mass concentrations of both the inhalable dust and nanoparticles were high. The nanoparticle fraction was 9-15% of the inhalable dust at the breathing zone of the dough maker. Different sources, such as ovens and doughnut baking affected the number size distribution. Flour dust contained nanoparticles but most of the fine and nanoparticles were released into the air from the oven operations. However, nanoparticles are not a primary concern in bakeries compared to health effects linked to the large flour particles such as flour-induced sensitization or asthma and development of occupational rhinitis.

Quantitative assessment of microbes from samples of indoor air and dust.

Different types of house dust samples are widely used as surrogates of airborne inhalation exposure in studies assessing health effects of indoor microbes. Here we studied-in a quantitative assessment-the representativeness of different house dust samples of indoor air (IA) and investigated seasonality and reproducibility of indoor samples. Microbial exposure was measured five times over 1 year in four rural and five urban Finnish homes. Six sampling methods were used: button inhalable aerosol sampler (actively collected personal and indoor air sampling), settled dust, floor dust, mattress dust and vacuum cleaner dust bag dust; the latter three referred to herein as "reservoir dust samples". Using quantitative PCR, we quantified the fungal species Cladosporium herbarum, the fungal group Penicillium/Aspergillus/Paecilomyces variotii, total fungal DNA, and Gram-positive and Gram-negative bacteria. We observed significant differences in microbial levels between rural and urban homes, most pronounced for personal air samples. Fungal species and groups but not total fungal DNA in indoor air correlated moderately to well with reservoir dust and with personal air samples. For bacterial groups, the correlations between air and dust were generally lower. Samples of indoor air and settled dust reflected similarly seasonal variation in microbial levels and were also similar compositionally, as assessed by ratios of qPCR markers. In general, determinations from mattress dust and other reservoir samples were better reproducible in repeated assessments over time than from indoor air or settled dust. This study indicates that settled dust reflects the microbial composition of indoor air and responds similarly to environmental determinants. Reservoir dusts tend to predict better microbial levels in indoor air and are more reproducible. Sampling strategies in indoor studies need to be developed based on the study questions and may need to rely on more than one type of sample.

Evaluation of Real-World Implementation of Partitioning and Negative Pressurization for Preventing the Dispersion of Dust From Renovation Sites.

OBJECTIVES: The aim of this study was to assess the implementation of partitioning and the negative pressure method in limiting the dispersion of dust to areas adjacent to renovation sites. METHODS: The pressure difference between the worksites and adjacent areas and PM10 concentrations in the both zones were measured in 12 renovation sites, and the factors affecting the prevention of dispersion of dust were assessed. RESULTS: Poor implementation of partitioning and negative pressurization found in half of the renovation sites lead difficulties in achieving a proper negative pressure, causing dispersion of dust into adjacent areas. Main problems related to flimsy partitioning walls and poor air tightness of the enclosure. Dust concentrations in adjacent areas were substantially lower when natural ventilation in the renovation site was rejected and partitioning walls and their junctions to existing structures were sealed. In case of leaky enclosures, despite the high air exchange rates, a definite negative pressure could not be maintained. Instead, negative pressure minimum of -5 Pa was found to be sufficient for limiting the dispersion of dust from renovation sites. CONCLUSIONS: Improvement on implementation of dust controls is required through revising the guidance documents, education, and efficient supervision. This study revealed that the current Finnish practice to implement the negative pressurization based on the air exchange rate achieved with the portable exhaust fans alone is not reasonable to assure adequate dust containment. Continuous negative pressure minimum of -5 Pa is suggested, and it should be monitored with alarm devices throughout the renovation processes.

Comparison of methods for assessing temporal variation of growth of fungi on building materials.

Fungal growth on indoor surfaces can decay building materials and release hazardous substances that affect indoor air quality. Despite the numerous methods available for growth determination, there is no commonly accepted standard. The goal of this study was to compare five different assay methods for the measurement of fungal growth: cultivation, MS-based determination of ergosterol, beta-N-acetylhexosaminidase activity, quantitative PCR and microscopic spore counting. Three fungal species (Aspergillus puulaauensis, Cladosporium montecillanum and Penicillium polonicum) were grown on three different building materials (two types of acoustic board and wood). Fungal load was determined at different time points. Results from all of the methods, except the spore count, showed good correlation between each other (r=0.6-0.8). Results obtained with the cultivation method had the highest variability among replicate samples (65 %), making it the least reproducible in repeated measurements. However, it also displayed the highest variability in incubation times (149 %), indicating its suitability for detecting transient changes in the physiological state of cells. Similar to the cultivation method, quantitative PCR correlated well with the other methods and had high variability in incubation times but had lower variability among replicate samples. Ergosterol and beta-N-acetylhexosaminidase enzyme activity seemed to be the methods least dependent on the physiological state of the cells. Varying growth dynamics were observed for different species over time with the different assay methods. Each one of the tests provides a different perspective on fungal quantification due to its specific responses to the various stages of fungal growth.

Release and characteristics of fungal fragments in various conditions.

Intact spores and submicrometer size fragments are released from moldy building materials during growth and sporulation. It is unclear whether all fragments originate from fungal growth or if small pieces of building materials are also aerosolized as a result of microbial decomposition. In addition, particles may be formed through nucleation from secondary metabolites of fungi, such as microbial volatile organic compounds (MVOCs). In this study, we used the elemental composition of particles to characterize the origin of submicrometer fragments released from materials contaminated by fungi. Particles from three fungal species (Aspergillus versicolor, Cladosporium cladosporioides and Penicillium brevicompactum), grown on agar, wood and gypsum board were aerosolized using the Fungal Spore Source Strength Tester (FSSST) at three air velocities (5, 16 and 27 m/s). Released spores (optical size, dp ≥ 0.8 µm) and fragments (dp ≤ 0.8 µm) were counted using direct-reading optical aerosol instruments. Particles were also collected on filters, and their morphology and elemental composition analyzed using scanning electron microscopes (SEMs) coupled with an Energy-Dispersive X-ray spectroscopy (EDX). Among the studied factors, air velocity resulted in the most consistent trends in the release of fungal particles. Total concentrations of both fragments and spores increased with an increase in air velocity for all species whereas fragment-spore (F/S) ratios decreased. EDX analysis showed common elements, such as C, O, Mg and Ca, for blank material samples and fungal growth. However, N and P were exclusive to the fungal growth, and therefore were used to differentiate biological fragments from non-biological ones. Our results indicated that majority of fragments contained N and P. Because we observed increased release of fragments with increased air velocities, nucleation of MVOCs was likely not a relevant process in the formation of fungal fragments. Based on elemental composition, most fragments originated from fungi, but also fragments from growth material were detected.

Negligible respiratory irritation and inflammation potency of pigmentary TiO2 in mice.

Titanium dioxide (TiO2) is manufactured in millions of tons yearly, and it is used widely as pigment in various applications. Until recently, TiO2 was considered toxicologically harmless and without adverse health effects. In this study, respiratory irritation and inflammation potencies of commercially available pigmentary TiO2 particles (<5 µm, rutile) were studied. Single head-only exposures (30 min) of male Crl:OF1 mice at mass concentrations 6, 11, 21, and 37 mg/m3, and repeated exposures (altogether 16 h, 1 h/day, 4 days/week for 4 weeks) of female BALB/c/Sca mice at mass concentration of 16 mg/m3 to pigmentary TiO2 were conducted. Minor sensory irritation was observed during acute and repeated exposures seen as elongation of the break after the inhalation, which is typical in sensory irritation, and caused by closure of the glottis inhibiting airflow from the lungs after inspiration. No pulmonary irritation, airflow limitation, nasal or pulmonary inflammation was observed. In conclusion, the respiratory irritation and inflammation potencies of the studied pigmentary TiO2 particles seemed to be low and thus can serve as an ideal control exposure agent in short-term studies in mice.

Thermal environment in eight low-energy and twelve conventional Finnish houses.

We assessed the thermal environment of eight recently built low-energy houses and twelve conventional Finnish houses. We monitored living room, bedroom and outdoor air temperatures and room air relative humidity from June 2012 to September 2013. Perceived thermal environment was evaluated using a questionnaire survey during the heating, cooling and interim seasons. We compared the measured and perceived thermal environments of the low-energy and conventional houses. The mean air temperature was 22.8 °C (21.9-23.8 °C) in the low-energy houses, and 23.3 °C (21.4-26.5 °C) in the conventional houses during the summer (1. June 2013-31. August 2013). In the winter (1. December 2012-28. February 2013), the mean air temperature was 21.3 °C (19.8-22.5 °C) in the low-energy houses, and 21.6 °C (18.1-26.4 °C) in the conventional houses. The variation of the air temperature was less in the low-energy houses than that in the conventional houses. In addition, the occupants were on average slightly more satisfied with the indoor environment in the low-energy houses. However, there was no statistically significant difference between the mean air temperature and relative humidity of the low-energy and conventional houses. Our measurements and surveys showed that a good thermal environment can be achieved in both types of houses.

Inhaled silica-coated TiO2 nanoparticles induced airway irritation, airflow limitation and inflammation in mice.

The wide use of nanotechnology is here to stay. However, the knowledge on the health effects of different engineered nanomaterials (ENMs) is lacking. In this study, irritation and inflammation potential of commercially available silica-coated TiO2 ENMs (10 × 40 nm, rutile) were studied. Single exposure (30 min) at mass concentrations 5, 10, 20 and 30 mg/m(3), and repeated exposure (altogether 16 h, 1 h/day, 4 days/week for 4 weeks) at mass concentration of 30 mg/m(3) to silica-coated TiO2 induced first phase of pulmonary irritation (P1), which was seen as rapid, shallow breathing. During repeated exposures, P1 effect was partly evolved into more intense pulmonary irritation. Also sensory irritation was observed at the beginning of both single and repeated exposure periods, and the effect intensified during repeated exposures. Airflow limitation started to develop during repeated exposures. Repeated exposure to silica-coated TiO2 ENMs induced also pulmonary inflammation: inflammatory cells infiltrated in peribronchial and perivascular areas of the lungs, neutrophils were found in BAL fluids, and the number of CD3 and CD4 positive T cells increased significantly. In line with these results, pulmonary mRNA expression of chemokines CXCL1, CXCL5 and CXCL9 was enhanced. Also expression of mRNA levels of proinflammatory cytokines TNF-α and IL-6 was elevated after repeated exposures. Taken together, these results indicated that silica-coated TiO2 ENMs induce pulmonary and sensory irritation after single and repeated exposure, and airflow limitation and pulmonary inflammation after repeated exposure.