Smouldering Combustion in Loose-Fill Wood Fibre Thermal Insulation: An Experimental Study

A bench-scale experimental setup has been used to study the conditions necessary for smouldering ignition in four types of loose-fill wood fibre thermal insulation, and to study the development of the smouldering process. The products varied with regard to wood species, grain size and fire retardant chemical additives. The test material was placed in an insulated open top container and heated from below. Temperatures within the sample and mass loss were measured during the tests. Both the fibre size and the level of added fire retardant seem to influence the smouldering ignition. Two different types of smouldering were identified in this study. Materials undergoing smouldering Type 1 obtained maximum temperatures in the range 380°C to 440°C and a total mass loss of 40 wt% to 50 wt%. Materials undergoing smouldering Type 2 obtained maximum temperatures in the range 660°C to 700°C and a total mass loss of 80 wt% to 90 wt%. This implies that Type 2 smouldering involves secondary char oxidation, which represents a risk for transition to flaming combustion and thereby a considerable fire hazard. This has been an exploratory project and the results must therefore be considered as indicative. The findings may, however, have implications for fire safety in the practical use of loose-fill wood fibre insulation in buildings, and further experimental studies should be performed with this in mind to obtain more knowledge about the topic.     

Effects of prenatal exposure to diesel exhaust particles on postnatal development, behavior, genotoxicity and inflammation in mice

Background

Results from epidemiological studies indicate that particulate air pollution constitutes a hazard for human health. Recent studies suggest that diesel exhaust possesses endocrine activity and therefore may affect reproductive outcome. This study in mice aimed to investigate whether exposure to diesel exhaust particles (DEP; NIST 2975) would affect gestation, postnatal development, activity, learning and memory, and biomarkers of transplacental toxicity. Pregnant mice (C57BL/6; BomTac) were exposed to 19 mg/m³ DEP (~1·10⁶ particles/cm³; mass median diameter ? 240 nm) on gestational days 9–19, for 1 h/day.

Results

Gestational parameters were similar in control and diesel groups. Shortly after birth, body weights of DEP offspring were slightly lower than in controls. This difference increased during lactation, so by weaning the DEP exposed offspring weighed significantly less than the control progeny. Only slight effects of exposure were observed on cognitive function in female DEP offspring and on biomarkers of exposure to particles or genotoxic substances.

Conclusion

In utero exposure to DEP decreased weight gain during lactation. Cognitive function and levels of biomarkers of exposure to particles or to genotoxic substances were generally similar in exposed and control offspring. The particle size and chemical composition of the DEP and differences in exposure methods (fresh, whole exhaust versus aged, resuspended DEP) may play a significant role on the biological effects observed in this compared to other studies.     

Lung inflammation and genotoxicity following pulmonary exposure to nanoparticles in ApoE-/- mice

Background  

The toxic and inflammatory potential of 5 different types of nanoparticles were studied in a sensitive model for pulmonary effects in apolipoprotein E knockout mice (ApoE^-/-). We studied the effects instillation or inhalation Printex 90 of carbon black (CB) and compared CB instillation in ApoE-/- and C57 mice. Three and 24 h after pulmonary exposure, inflammation was assessed by mRNA levels of cytokines in lung tissue, cell composition, genotoxicity, protein and lactate dehydrogenase activity in broncho-alveolar lavage (BAL) fluid.     

Monitoring success of remediation: seven case studies of moisture and mold damaged buildings

Based on seven case studies of buildings that underwent different degrees of moisture and mold damage remediation, we aimed to develop methodology for assessment of the success of the remediation process. Methods used in gauging the success included technical monitoring of performance of building structures and heating, ventilation and air conditioning (HVAC) systems, microbial monitoring of indoor air quality (IAQ), and health effects studies of building occupants. The assessment was based on measurable change in the situations before and after remediation. Based on technical monitoring, remediation was successful in three cases, with partial improvement noted in three cases, whereas no remediation was conducted in one case. Based on microbial monitoring, improvement was detected in one, partial improvement in two and no improvement in two cases, whereas no follow-up was conducted in two cases. Health effect studies (mainly self-reported health status) showed improvement in one case, partial improvement in two cases, and no improvement in two cases, whereas no follow-up was conducted in one case, and in one case, follow-up failed due to low response rate. The results illustrate that it is possible to monitor the effects of remediation using various metrics. However, in some cases, no improvement could be observed in IAQ or occupant health, even if the remediation was considered technically successful, i.e. the remediation was fully completed as recommended. This could be due to many reasons, including: 1) all damage may not have been addressed adequately; 2) IAQ or health may not have been perceived improved regardless of remediation; and/or 3) the methods used may not have been sensitive/specific enough to detect such improvement within the 6-12 months follow-up periods after completion of the remediation. There is a need to further develop tools for monitoring and assessment of the success of moisture damage remediation in buildings.     

Cytokine expression in mice exposed to diesel exhaust particles by inhalation. Role of tumor necrosis factor

Background  

Particulate air pollution has been associated with lung and cardiovascular disease, for which lung inflammation may be a driving mechanism. The pro-inflammatory cytokine, tumor necrosis factor (TNF) has been suggested to have a key-role in particle-induced inflammation.     

RECURSIVE ESTIMATION IN SWITCHING AUTOREGRESSIONS WITH A MARKOV REGIME

Abstract. A hidden Markov regime is a Markov process that governs the time or space dependent distributions of an observed stochastic process. We propose a recursive algorithm for parameter estimation in a switching autoregressive process governed by a hidden Markov chain. A common approach to the recursive estimation problem is to base the estimation on suboptimal modifications of Kalman filtering techniques. The main idea in this paper is to use the maximum likelihood method and from this develop a recursive EM algorithm.