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From strange bedfellows to natural allies: the shifting allegiance of fire service organisations in the push for federal fire-safe cigarette legislation.

BACKGROUND: Cigarettes are the leading cause of fatal fires in the USA and are associated with one in four fire deaths. Although the technology needed to make fire-safe cigarettes has been available for many years, progress has been slow on legislative and regulatory fronts to require the tobacco industry to manufacture fire-safe cigarettes. METHOD AND RESULTS: We conducted a case study, drawing on data from tobacco industry documents, archives, and key informant interviews to investigate tobacco industry strategies for thwarting fire-safe cigarette legislation in the US Congress. We apply a theoretical framework that posits that policymaking is the product of three sets of forces: interests, institutions, and ideas, to examine tobacco industry behaviour, with a special focus on their and others' attempts to court fire service organisations, including firefighters' unions as allies. We discuss the implications of our findings for future policy efforts related to fire-safe cigarettes and other tobacco control issues. CONCLUSIONS: Tobacco control advocates ought to: continue efforts to align key interest groups, including the firefighters unions; contest tobacco industry "diversionary" science tactics; and pursue a state based legislative strategy for fire-safe cigarettes, building towards national legislation.

Consumer Product Safety↗

The application of NIST's Fire Dynamics Simulator to the investigation of carbon monoxide exposure in the deaths of three Pittsburgh fire fighters.

A case is reported in which computer fire modeling was used to reevaluate a fire that killed three fire fighters. NIST's Fire Dynamics Simulator (FDS) was employed to model the fire in order to estimate the concentration of carbon monoxide present in the dwelling, which was the immediate cause of death of two of the fire fighters, who appear to have removed their face pieces in order to share available air. This estimate, along with an assumed respiration volume and known blood carboxyhemoglobin, was plugged into a standard equation to estimate the time of exposure. The model indicated that 27 min into the fire, the carbon monoxide concentration had already reached approximately 3600 ppm. At this concentration, and a respiration of 70 L/min, an estimated 3 to 8 min of exposure would have been required to accumulate the concentrations of carboxyhemoglobin (49, 44, and 10%) measured on the fire fighters at autopsy.

Carbon Monoxide Poisoning↗

Effect of a long-term fire retardant (Fire Trol 934) on the germination of nine Mediterranean-type shrub species.

Fire Trol 934 is a long-term fire retardant commonly used in fire prevention and extinction. Our objective was to determine the effect of this chemical on seed germination of nine plant species from Mediterranean-type shrublands, where these chemicals are potentially used. Seeds were exposed to five different Fire Trol concentrations, (0 (control) to 10%, on a log scale) and monitored in a germination chamber for nine weeks. Seeds from four Cistus species were subjected to an additional heat treatment that simulated thermal scarification caused by fire. Retardant exposure caused a significant decrease in total germination in all species, and exposure to the highest Fire Trol concentration (10%) resulted in complete inhibition of germination. However, the sensitivity to Fire Trol varied across species and this differential species sensitivity may potentially lead to different impacts in the soil seed banks depending on whether sites are burned or unburned. Exposure to Fire Trol 934 may affect recruitment of shrubland species particularly during dry autumns, due to limited leaching of these chemicals from the soil surface. Consequently, its use should be avoided in sites where particularly sensitive plant species are present.

Cistaceae↗

Time-course of changes in firing rates and firing patterns of subthalamic nucleus neuronal activity after 6-OHDA-induced dopamine depletion in rats.

The subthalamic nucleus (STN) plays a key role in motor control. Disorganization of its neuronal activity is implicated in the manifestation of parkinsonian motor symptoms. The aim of the present work was to study the time-course of changes in the firing activity of STN neurons in a rat model of parkinsonism. Electrophysiological recordings were done in normal rats and four groups of rats at different time points after 6-hydroxydopamine (6-OHDA) microinjection into the pars compacta of substantia nigra (SNc). Results showed a significant decrease in firing rate during the first and second weeks post lesion (5.53+/-0.56 and 7.66+/-0.73 spikes/s, respectively) compared to normal rats (11.13+/-0.59 spikes/s). From the 3rd week after 6-OHDA injection the firing rates returned toward baseline, with an average of 9.71+/-0.51 spikes/s during the 3rd week and 11.13+/-0.71 spikes/s during the 4th week. With regard to firing pattern, the majority of STN cells (90%) discharged regularly or slightly irregularly in normal animals. Only 4% exhibited burst activity and 6% had mixed firing patterns. After SNc-lesion, the percentage of cells exhibiting burst and mixed patterns increased progressively from 35% during the first week to 56% at week 4 post-lesion. In sum, these experiments revealed that the firing rate of STN neurons was altered only transiently following nigral lesions, whereas a progressive and stable change in the firing pattern was observed up to 4 weeks post lesion, suggesting that the persistence of bursts firing more closely relates to the motor pathologies of this rat model of parkinsonism.

Action Potentials↗

Firing rate of the noisy quadratic integrate-and-fire neuron.

We calculate the firing rate of the quadratic integrate-and-fire neuron in response to a colored noise input current. Such an input current is a good approximation to the noise due to the random bombardment of spikes, with the correlation time of the noise corresponding to the decay time of the synapses. The key parameter that determines the firing rate is the ratio of the correlation time of the colored noise, tau(s), to the neuronal time constant, tau(m). We calculate the firing rate exactly in two limits: when the ratio, tau(s)/tau(m), goes to zero (white noise) and when it goes to infinity. The correction to the short correlation time limit is O(tau(s)/tau(m)), which is qualita tively different from that of the leaky integrate-and-fire neuron, where the correction is O( radical tau(s)/tau(m)). The difference is due to the different boundary conditions of the probability density function of the membrane potential of the neuron at firing threshold. The correction to the long correlation time limit is O(tau(m)/tau(s)). By combining the short and long correlation time limits, we derive an expression that provides a good approximation to the firing rate over the whole range of tau(s)/tau(m) in the suprathreshold regime-that is, in a regime in which the average current is sufficient to make the cell fire. In the subthreshold regime, the expression breaks down somewhat when tau(s) becomes large compared to tau(m).

Action Potentials↗

Firing properties of spinal interneurons during voluntary movement. I. State-dependent regularity of firing.

The firing properties of single spinal interneurons (INs) were studied in five awake, behaving monkeys performing isometric or auxotonic flexion-extension torques at the wrist. INs tended to fire tonically at rest (mean rate, 14 spikes (sp)/sec) and during generation of static torque (mean rate, 19 sp/sec in flexion, 24 sp/sec in extension). INs exhibited regular firing, with autocorrelation functions showing clear periodic features and a mean coefficient of variation of interspike intervals (CV) of 0.55 during production of static torque. For the population, there was an inverse correlation between CV and mean rate. However, 46% of the INs had task-dependent changes in regularity that were not predicted by changes in firing rate, suggesting that their firing pattern is determined not only by the intrinsic properties of the neurons but also by the properties of its synaptic inputs. INs showed two main response types to passive wrist displacement: biphasic and coactivation. Cells with these sensory responses had different, stereotypical temporal activity profiles and firing regularity during active movement. However, INs having correlational linkages with forearm muscles, identified as features in spike-triggered averages of electromyographic activity, did not exhibit unique responses or firing properties, although they tended to fire more regularly than other INs. This suggests the lack of a precise mapping of inputs to outputs for the spinal premotor network.

Action Potentials↗

Modeling fire-induced smoke spread and carbon monoxide transportation in a long channel: Fire Dynamics Simulator comparisons with measured data.

Smoke and toxic gases, such as carbon monoxide, are the most fatal factors in fires. This paper models fire-induced smoke spread and carbon monoxide transportation in an 88m long channel by Fire Dynamics Simulator (FDS) with large eddy simulation (LES). FDS is now a well-founded fire dynamics computational fluid dynamic (CFD) program, which was developed by National Institute of Standards and Technology (NIST). Two full scale experiments with fire sizes of 0.75 and 1.6MW were conducted in this channel to validate the program. The spread of the fire-induced smoke flow together with the smoke temperature distribution along the channel, and the carbon monoxide concentration at an assigned position were measured. The FDS simulation results were compared with experimental data with fairly good agreement demonstrated. The validation work is then extended to numerically study the carbon monoxide concentration distribution, both vertically and longitudinally, in this long channel. Results showed that carbon monoxide concentration increase linearly with the height above the floor and decreases exponentially with the distance away from the fire source.

Carbon Monoxide↗

Indoor respirable particulate matter concentrations from an open fire, improved cookstove, and LPG/open fire combination in a rural Guatemalan community.

Improved biomass cookstoves have the potential to reduce pollutant emissions and thereby reduce pollution exposure among populations in developing countries who cook daily with biomass fuels. However, evaluation of such interventions has been very limited. This article presents results from a study carried out in 30 households in rural Guatemala. Twenty-four hour PM3.5 concentrations were compared over 8 months for three fuel/cookstove conditions (n = 10 households for each condition): a traditional open fire cookstove, an improved cookstove called the plancha mejorada, and a liquefied petroleum gas (LPG) stove/open fire combination. Twenty-four hour geometric mean PM3.5 concentrations were 1560 micrograms/m3 (n = 58; 95% C.I. 1310, 1850), 280 micrograms/m3 (n = 59; 95% C.I. 240-320), and 850 micrograms/m3 (n = 60; 95% C.I. 680-1050) for the open fire, plancha, and LPG/open fire combination, respectively. A generalized estimating equation model showed a 45% reduction in PM3.5 concentrations for the LPG/open fire combination as compared to the open fire alone. The difference approached significance (p < 0.0737). The plancha showed an 85% reduction in PM3.5 concentrations as compared to the open fire (p < 0.0001). An analysis of the interaction of time with stove type showed that the temporal trend in pollution did not significantly differ among the three stove types. The reduced PM3.5 concentrations were maintained over time. Season did not affect pollutant concentrations. Of the two interventions, the plancha appears to offer the best prospects for achieving substantial reductions in indoor air pollution levels, although issues of cost and stove maintenance remain to be addressed.

Air Pollution, Indoor↗

Effects of fire and fire intensity on the germination and establishment of Acacia karroo, Acacia nilotica, Acacia luederitzii and Dichrostachys cinerea in the field.

BACKGROUND: While fire has been used in some instances to control the increase of woody plants, it has also been reported that fire may cause an increase in certain fire-tolerant Acacia tree species. This study investigated germination of Acacia karroo, A. luederitzii and Dichrostachys cinerea, thought to be increasing in density, as well as the historically successful encroaching woody species, A. nilotica, in savanna grassland, Hluhluwe-iMfolozi Park, South Africa. A. karroo is thought to be replacing A. nilotica as the dominant microphyllous species in the park. We tested the hypothesis that observed increases in certain woody plants in a savanna were related to seed germination and seedling establishment. Germination is compared among species for burnt and unburnt seeds on burnt and unburnt plots at three different locations for both hot and cool fires. RESULTS: Acacia karroo showed higher germination (A. karroo 5.1%, A. nilotica 1.5% and A. luederitzii 5.0%) levels and better establishment (A. karroo 4.9%, A. nilotica 0.4% and A. luederitzii 0.4%). Seeds of the shrub Dichrostachys cinerea did not germinate in the field after fire and it is thought that some other germination cue is needed. On average, burning of A. karroo, A. nilotica and A. luederitzii seeds did not affect germination. There was a significant difference in the germination of burnt seeds on burnt sites (4.5%) and burnt seeds on unburnt plots (2.5%). Similarly, unburnt seeds on unburnt sites germinated better (4.9%) than unburnt seeds on burnt sites (2.8%). CONCLUSION: We conclude that a combination of factors may be responsible for the success of A. karroo and that fires may not be hot enough or may occur at the wrong time of year to control A. karroo establishment in HiP. Although germination and establishment of A. karroo was higher than for A. nilotica a competitive advantage after fire could not be shown.

Acacia↗

The spontaneous firing patterns of forebrain neurons. III. Prevention of induced asymmetries in caudate neuronal firing rates by unilateral thalamic lesions.

Unilateral lesions interrupting striatal outputs and inputs (MFB lesions) produce a marked slowing of neuronal firing in the caudate nucleus contralateral to the side of the lesions without affecting neuronal firing in the ipsilateral caudate nucleus. Although the MFB lesion also interrupts the nigrostriatal pathway and depletes the ipsilateral striatum of dipamine and its associated enzymes, the slowing of unit firing rates is apparently due to interruption of striatal outputs rather than inputs. Unilateral thalamic lesions palced ipsilateral to MFB lesions in iether the ventral anterior-ventrolateral nuclei (VA-VL) or in the center median-parafascicular nuclei (CM-PF) prevent the MFB lesion-induced asymmetry in caudate neuronal firing rates. These thalamic lesions do not, however, restore the striatal dopamine content depleted by the MFB lesion. Unilateral CM-PF lesions in otherwise intact cats do not alter caudate unit firing rates nor do they affect striatal dopamine. VA-VL lesions in otherwise intact cats produce a bilateral slowing in the spontaneous firing of neurons in the caudate nuclei, again, whithout altering caudate dopamine concentrations. These results provide further evidence that caudate dopamine concentration per se does not appear to be a potent variable in controlling the spontaneous firing rates of striatal neurons.

Animals↗

Relationship between the firing frequency of injured peripheral neurons and inhibition of firing by sodium channel blockers.

UNLABELLED: Animal models of neuropathic pain in which a peripheral nerve is damaged result in spontaneous activity in primary afferents that can be inhibited by intravenous administration of sodium channel blockers. Many of these compounds exhibit use-dependent block of sodium current, leading to the prediction that they should more readily inhibit neurons that fire at higher frequencies. This prediction was tested in 2 rat models of nerve injury, L5 spinal nerve section and sciatic nerve section. Sciatic nerve section produced average firing frequencies that were higher than spinal nerve section and often manifested as high-frequency bursting. Inhibition of firing by intravenous sodium channel blockers was longer lasting in this model. Within each model, higher frequency of firing did not translate into more effective block. In the spinal nerve section model, there was a robust inverse correlation between frequency and inhibition. Within the sciatic section model, only neurons that fired in rhythmic bursts were inhibited, and again, those firing at lower mean frequencies were more effectively inhibited. These results indicate that the efficacy of sodium channel blockers depends on the nature of the injury and the pattern of the resulting activity rather than simply the frequency of action potentials generated. PERSPECTIVE: This study examines the ability of frequency-dependent sodium channel blockers to inhibit spontaneous firing of injured peripheral nerves in vivo. It outlines the conditions under which inhibition is more and less effective and will provide insight into conditions under which sodium channel blockers are likely to be therapeutically useful.

Anesthetics, Local↗

Firing rate and firing synchrony distinguish dynamic from steady state sound.

The role of firing-rate and firing synchrony within and between three auditory cortical areas in coding complex sounds was investigated. In cortex, steady-state sound rarely caused any difference in firing rate over the spontaneous rate, but induced greater neural synchrony within and between cortical areas than were present during silence. Dynamic changes, other than onsets, produced similar synchrony as steady-state stimulation, but the firing rates were significantly larger in each cortical area than for steady-state sound. This suggests that the firing rate signals the difference between dynamic and steady-state stimulation. Because firing rates are high for stimulus onsets, the combination of firing rate and intercortical synchrony may distinguish between dynamic and steady-state stimuli and silence.

Acoustic Stimulation↗

Internal pallidal neuronal activity during mild drug-related dyskinesias in Parkinson's disease: decreased firing rates and altered firing patterns.

The neuronal basis of hyperkinetic movement disorders has long been unclear. We now test the hypothesis that changes in the firing pattern of neurons in the globus pallidus internus (GPi) are related to dyskinesias induced by low doses of apomorphine in patients with advanced Parkinson's disease (PD). During pallidotomy for advanced PD, the activity of single neurons was studied both before and after administration of apomorphine at doses just adequate to induce dyskinesias (21 neurons, 17 patients). After the apomorphine injection, these spike trains demonstrated an initial fall in firing from baseline. In nine neurons, the onset of on was simultaneous with that of dyskinesias. In these spike trains, the initial fall in firing rate preceded and was larger than the fall at the onset of on with dyskinesias. Among the three neurons in which the onset of on occurred before that of dyskinesias, the firing rate did not change at the time of onset of dyskinesias. After injection of apomorphine, dyskinesias during on with dyskinesias often fluctuated between transient periods with dyskinesias and those without. Average firing rates were not different between these two types of transient periods. Transient periods with dyskinesias were characterized by interspike interval (ISI) independence, stationary spike trains, and higher variability of ISIs. A small but significant group of neurons demonstrated recurring ISI patterns during transient periods of on with dyskinesias. These results suggest that mild dyskinesias resulting from low doses of apomorphine are related to both low GPi neuronal firing rates and altered firing patterns.

Aged↗

Efficacy of cognitive-behavioral treatment and fire safety education for children who set fires: initial and follow-up outcomes.

The efficacy of cognitive-behavioral treatment (CBT) and fire safety education (FSE) for children who had set a recent fire was evaluated. Assessments were conducted with 38 children who were randomly assigned to CBT or FSE and with another 16 children who received a brief intervention (home visit from a firefighter or HVF) that paralleled routine services. Measures in four domains related to the child's fire history were obtained from children and their parents at pre-treatment, post-assessment, and 1-year follow-up. There were several improvements at post-treatment for all conditions on measures of fire involvement, interest, and risk. However, CBT and FSE were more efficacious than HVF on certain measures, including the frequency of firesetting and proportion of children playing with matches, severity of individualized problems with fire, and involvement in fire-related acts and other deviant fire activities. These and other group differences, along with certain time effects, were evident at 1-year follow-up. The findings from this initial comparison study are discussed in the context of needed clinical and research directions for work with firesetters and their families.

Adolescent↗

Characteristics of fire victims in different sorts of fires.

We studied retrospectively 286 cases of fire deaths from a 10 year period. The victims were classified according to the type of fire. Among the victims of smouldering fire, 80% had lethal HbCO saturations, whereas only 30% had such saturations when an accelerant had been used. The third group consisted of victims of fires in which the type of fire was, for various reasons, undetermined. HbCO saturations were not influenced by sex, age, concomitant disease or blood alcohol concentration. In eight cases neither respiratory soot nor HbCO was detected in spite of evidence that the deceased was alive as the fire broke out. The material included nine cases of homicide and 22 cases of suicide.

Adolescent↗

Effect of an uncontrolled fire and the subsequent fire fight on the chemical composition of landfill leachate.

Landfill leachates sampled during and after an accidental landfill fire were analysed and the levels of selected metals and chemical compounds compared to those occurring in the leachate under normal conditions. The fire at the landfill site was put out by excavation and cooling by use of water. The investigation during the fire and fire fight revealed a moderate increase in the level of nitrogen and also in pH and conductivity. Heavy metals and COD in the leachate showed considerably increased levels. In general, the determined variables appeared to normalise within one week after the fire was extinguished. It can be concluded that landfill fires extinguished by excavation may lead to elevated leachate levels of especially COD and heavy metals, but that this is only a short-term effect.

Fires↗

An assessment of air quality impacts of fires associated with fire fighting operations.

Fire fighters in Canada's navy must undergo regular training with fires from simulated helicopter crashes. Visible emissions from these fires often create health concerns in surrounding communities. This paper presents air quality implications of plume dispersion associated with "helicopter fires." Evaluations involved measuring plume rise, estimating emissions, dispersion modeling and ambient monitoring. Results of the evaluation provided ground-level concentration estimates of plume particulate matter, oxides of nitrogen, hydrogen fluoride, carbon monoxide, 22 metals, 15 PAH and 13 VOC. The study showed that the air quality impact of the fire fighting training is much lower than the relevant time-weighted averages established to protect workers' health. This paper will be of interest to people in environmental protection agencies because it demonstrates the effects of fire fighting operations that must frequently occur as part of training exercises.

Air Pollutants↗

Inhibition of firing rate and changes in the firing pattern of nigral dopamine neurons by gamma-hydroxybutyric acid (GHBA) are specifically induced by activation of GABA(B) receptors.

Previous studies have shown that administration of gamma-hydroxybutyric acid (GHBA) or the GABA(B) receptor agonist baclofen are associated with a decrease in firing rate, a regularisation of firing pattern and a decrease in burst activity of midbrain dopamine (DA) neurons in the substantia nigra (SN). In the present study we compared the ability of the novel GABA(B) receptor antagonist SCH 50911 and the selective antagonist of GHBA binding sites, NCS-382, to antagonise the effects of baclofen or GHBA, respectively, on the neuronal activity of DA neurons in anaesthetised rats. SCH 50911 (75 mg/kg, i.v.) was found to antagonise the decrease in firing rate, the regularisation of firing rhythm and the decrease of burst activity in DA cells, induced by baclofen (1-32 mg/kg, i.v.) or GHBA (12.5-1600 mg/kg, i.v.). NCS-382 (100 mg/kg, i.v.) did not affect the baclofen-induced changes in neuronal activity. Neither was the drug able to influence the GHBA-induced alterations in firing rate or in burst activity, although NCS-382 to some extent antagonised the regularisation of the firing pattern observed following low doses of GHBA (< or =100 mg/kg). The results of the present study give further support for the notion that the GHBA-induced changes in neuronal activity of nigral dopamine neurons are mediated by stimulation of GABA(B) receptors.

Animals↗