Jorma Jokiniemi

Airway Exposure to Silica-Coated TiO2 Nanoparticles Induces Pulmonary Neutrophilia in Mice

The importance of nanotechnologies and engineered nanoparticles has grown rapidly. It is therefore crucial to acquire up-to-date knowledge of the possible harmful health effects of these materials. Since a multitude of different types of nanosized titanium dioxide (TiO(2)) particles are used in industry, we explored their inflammatory potential using mouse and cell models. BALB/c mice were exposed by inhalation for 2 h, 2 h on 4 consecutive days, or 2 h on 4 consecutive days for 4 weeks to several commercial TiO(2) nanoparticles, SiO(2) nanoparticles, and to nanosized TiO(2) generated in a gas-to-particle conversion process at 10 mg/m(3). In addition, effects of in vitro exposure of human macrophages and fibroblasts (MRC-9) to the different particles were assessed. SiO(2)-coated rutile TiO(2) nanoparticles (cnTiO(2)) was the only sample tested that elicited clear-cut pulmonary neutrophilia. Uncoated rutile and anatase as well as nanosized SiO(2) did not induce significant inflammation. Pulmonary neutrophilia was accompanied by increased expression of tumor necrosis factor-alpha (TNF-alpha) and neutrophil-attracting chemokine CXCL1 in the lung tissue. TiO(2) particles accumulated almost exclusively in the alveolar macrophages. In vitro exposure of murine and human macrophages to cnTiO(2) elicited significant induction of TNF-alpha and neutrophil-attracting chemokines. Stimulation of human fibroblasts with cnTiO(2)-activated macrophage supernatant induced high expression of neutrophil-attracting chemokines, CXCL1 and CXCL8. Interestingly, the level of lung inflammation could not be explained by the surface area of the particles, their primary or agglomerate particle size, or radical formation capacity but is rather explained by the surface coating. Our findings emphasize that it is vitally important to take into account in the risk assessment that alterations of nanoparticles, e.g., by surface coating, may drastically change their toxicological potential.

Comparison of Different Dilution Methods for Measuring Diesel Particle Emissions

Particle emissions from a turbo-charged diesel off-road engine were characterized with DMA + CNC and electron microscopy for comparison of different sampling and dilution systems. Four different sampling methods were used: (1) two ejector diluters, (2) partial flow and ejector diluter, (3) porous tube and ejector diluter, and (4) porous tube diluter. Number size distributions for partial flow and ejector dilution had modes at 25–30 nm and at 45–50 nm independent of the dilution ratio. The mode at 25–30 nm indicated nucleation during dilution in these experiments and was clearly most significant for the partial flow and ejector diluter setup. This was attributed to the temperature difference between exhaust gas, sample line, and partial flow diluter and cold dilution air. For other dilution systems the main mode was at 45 nm and indications of a mode at 15–20 nm were observed depending on the dilution ratio. Especially for the porous tube diluter, the main mechanism for particle growth was condensation on the surfaces of the existing particles. According to this study the best dilution system for obtaining a number size distribution without any significant nucleation effects was the porous tube dilution setup.

Industrial worker exposure to airborne particles during the packing of pigment and nanoscale titanium dioxide

Context: Titanium dioxide (TiO2) factory workers’ source specific exposure and dose to airborne particles was studied extensively for particles between 5 nm and 10 μm in size. Objective: We defined TiO2 industry workers’ quantitative inhalation exposure levels during the packing of pigment TiO2 (pTiO2) and nanoscale TiO2 (nTiO2) material from concentrations measured at work area. Methods: Particle emissions from different work events were identified by linking work activity with the measured number size distributions and mass concentrations of particles. A lung deposit model was used to calculate regional inhalation dose rates in units of particles min−1 and μg min−1 without use of respirators. Results: Workers’ average exposure varied from 225 to 700 μg m−3 and from 1.15 × 104 to 20.1 × 104 cm−4. Over 90% of the particles were smaller than 100 nm. These were mainly soot and particles formed from process chemicals. Mass concentration originated primarily from the packing of pTiO2 and nTiO2 agglomerates. The nTiO2 exposure resulted in a calculated dose rate of 3.6 × 106 min−1 and 32 μg min−1 where 70% of the particles and 85% of the mass was deposited in head airways. Conclusions: The recommended TiO2 exposure limits in mass by NIOSH and in particle number by IFA were not exceeded. We recommend source-specific exposure assessment in order to evaluate the workers’ risks. In nTiO2 packing, mass concentration best describes the workers’ exposure to nTiO2 agglomerates. Minute dose rates enable the simulation of workers’ risks in different exposure scenarios.

Toxicological effects of emission particles from fossil- and biodiesel-fueled diesel engine with and without DOC/POC catalytic converter

There is increasing demand for renewable energy and the use of biodiesel in traffic is a major option when implying this increment. We investigated the toxicological activities of particulate emissions from a nonroad diesel engine, operated with conventional diesel fuel (EN590), and two biodiesels: rapeseed methyl ester (RME) and hydrotreated fresh vegetable oil (HVO). The engine was operated with all fuels either with or without catalyst (DOC/POC). The particulate matter (PM1) samples were collected from the dilution tunnel with a high-volume cascade impactor (HVCI). These samples were characterized for ions, elements, and polycyclic aromatic hydrocarbon (PAH) compounds. Mouse RAW264.7 macrophages were exposed to the PM samples for 24 h. Inflammatory mediators, (TNF-α and MIP-2), cytotoxicity, genotoxicity, and oxidative stress (reactive oxygen species [ROS]) were measured. All the samples displayed mostly dose-dependent toxicological activity. EN590 and HVO emission particles had larger inflammatory responses than RME-derived particles. The catalyst somewhat increased the responses per the same mass unit. There were no substantial differences in the cytotoxic responses between the fuels or catalyst use. Genotoxic responses by all the particulate samples were at same level, except weaker for the RME sample with catalyst. Unlike other samples, EN590-derived particles did not significantly increase ROS production. Catalyst increased the oxidative potential of the EN590 and HVO-derived particles, but decreased that with RME. Overall, the use of biodiesel fuels and catalyst decreased the particulate mass emissions compared with the EN590 fuel. Similar studies with different types of diesel engines are needed to assess the potential benefits from biofuel use in engines with modern technologies.

Numerical simulation of vapour-aerosol dynamics in combustion processes

Abstract A computer model (ABC-code) has been constructed to describe the steady one-dimensional aerosol dynamics in combustion processes for gas and particle interactions at post-combustion conditions. The aerosol general dynamic equation has been solved numerically using a discrete-nodal point method for describing the particle size distribution. In the present model we consider those mechanisms that will affect the dynamics of alkali species after volatilisation, i.e. nucleation, condensation, coagulation, chemical reactions and deposition. The main features of the ABC code have been explained and an example calculation has been carried out for simulation of aerosol dynamics and alkali vapour behaviour in a real scale pulverised coal fired boiler. The results show that for predicting the gas phase concentrations of alkali species at different temperatures it is important to know the volatilisation of sodium, potassium, chlorine and sulphur and the formation rate of alkali sulphates in the gas phase. The initial ash size distribution determines the distribution of condensed alkalis between sub- and supermicron particle modes. The choice of the homogeneous nucleation model has some importance for the calculated submicron number size distribution. The effect of heterogeneous nucleation to initiate condensation on ash particles was negligible. The predictions of our simulation are in a qualitative agreement with the experimental results. The utilisation of the present code will lead to a better understanding of aerosol behaviour which will be of great importance for the control of toxic flue gas emissions, slagging and fouling in commercial boilers.

COMPUTATIONAL FLUID DYNAMICS BASED SECTIONAL AEROSOL MODELLING SCHEMES

Abstract A computational fluid dynamics based sectional aerosol model is introduced. One of the motivations and the first test case is the simulation of aerosol formation via nucleation in laminar flow reactors. Simulation results are compared with experiments and simulations with other modelling concepts presented in the literature. The main scheme is based on a boundary layer type solution of sectional aerosol equations that uses flow fields provided a computational fluid dynamics (CFD) code. Special attention has been paid to the computational aspects and it is demonstrated that the scheme yields accurate grid-independent solutions in reasonable computation times. An alternative method based on full sectional Eulerian simulation has also been developed. Due to excessive demands on CFD grid resolution, an attempt to simulate aerosol formation in a laminar flow reactor with this scheme failed to provide accurate predictions.

Pulmonary inflammation and tissue damage in the mouse lung after exposure to PM samples from biomass heating appliances of old and modern technologies

Current levels of ambient air fine particulate matter (PM(2.5)) are associated with mortality and morbidity in urban populations worldwide. In residential areas wood combustion is one of the main sources of PM(2.5) emissions, especially during wintertime. However, the adverse health effects of particulate emissions from the modern heating appliances and fuels are poorly known. In this study, health related toxicological properties of PM(1) emissions from five modern and two old technology appliances were examined. The PM(1) samples were collected by using a Dekati® Gravimetric Impactor (DGI). The collected samples were weighed and extracted with methanol for chemical and toxicological analyses. Healthy C57BL/6J mice were intratracheally exposed to a single dose of 1, 3, 10 or 15 mg/kg of the particulate samples for 4, 18 or 24h. Thereafter, the lungs were lavaged and bronchoalveolar lavage fluid (BALF) was assayed for indicators of inflammation, cytotoxicity and genotoxicity. Lungs of 24h exposed mice were collected for inspection of pulmonary tissue damage. There were substantial differences in the combustion qualities of old and modern technology appliances. Modern technology appliances had the lowest PM(1) (mg/MJ) emissions, but they induced the highest inflammatory, cytotoxic and genotoxic activities. In contrast, old technology appliances had clearly the highest PM(1) (mg/MJ) emissions, but their effect in the mouse lungs were the lowest. Increased inflammatory activity was associated with ash related components of the emissions, whereas high PAH concentrations were correlating with the smallest detected responses, possibly due to their immunosuppressive effect.

Bipolar charged aerosol agglomeration with alternating electric field in laminar gas flow

Abstract This paper presents the results of an experimental study for a method of increasing the efficiency of electrostatic precipitators for the collection of fly ash particles of submicron size. An alternating electric field was used to induce agglomeration of bipolarly charged particles (bipolar AC-agglomeration). A bench-scale AC-agglomeration test apparatus with bipolar corona charger was constructed. Test aerosol was generated from vegetable oil. The total mass loading was 0.2 gm−3 (5 × 106 particles cm−3), mass median diameter was 0.5 μm. Count median diameter was 0.2 μm, and geometrical standard deviation was 1.8. Residence time in the agglomerator was 4.8 s and the agglomerator field was 5.0 kV cm−1 (rms). Systematic experiments were conducted to investigate the agglomeration efficiency of the system. The percentage decrease in number concentration of 0.1–1.0 μm sized particles was found to be between 17 and 19%.

Particulate Matter from Both Heavy Fuel Oil and Diesel Fuel Shipping Emissions Show Strong Biological Effects on Human Lung Cells at Realistic and Comparable In Vitro Exposure Conditions

Background Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling. Objectives To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols. Methods Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses. Results The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon (“soot”). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification. Conclusions Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the use of HFO and DF we recommend a reduction of carbonaceous soot in the ship emissions by implementation of filtration devices.

Effects of a catalytic converter on PCDD/F, chlorophenol and PAH emissions in residential wood combustion.

Catalytic converters can be used to decrease carbon monoxide, organic compounds and soot from small-scale wood-fired appliances. The reduction is based on the oxidation of gaseous and particulate pollutants promoted by catalytic transition metal surfaces. However, many transition metals have also strong catalytic effect on PCDD/F formation. In this study birch logs were burned in a wood-fired stove (18 kW) with and without a catalytic converter with palladium and platinum as catalysts. PCDD/F, chlorophenol and PAH concentrations were analyzed from three phases of combustion (ignition, pyrolysis and burnout) and from the whole combustion cycle. PCDD/F emissions without the catalytic converter were at a level previously measured for wood combustion (0.15-0.74 ng N m(-3)). PAH emissions without the catalytic converter were high (47-85 mg N m(-3)) which is typical for batch combustion of wood logs. Total PAH concentrations were lower (on average 0.8-fold), and chlorophenol and PCDD/F levels were substantially higher (4.3-fold and 8.7-fold, respectively) when the catalytic converter was used. Increase in the chlorophenol and PCDD/F concentrations was most likely due to the catalytic effect of the platinum and palladium. Platinum and palladium may catalyze chlorination of PCDD/Fs via the Deacon reaction or an oxidation process. The influence of emissions from wood combustion to human health and the environment is a sum of effects caused by different compounds formed in the combustion. Therefore, the usage of platinum and palladium based catalytic converters to reduce emissions from residential wood combustion should be critically evaluated before wide-range utilization of the technology.