Confocal microscopy 3D imaging of diesel particulate matter.

To date, diesel particulate matter (DPM) has been described as aggregates of spherule particles with a smooth appearing surface. We have used a new colour confocal microscope imaging method to study the 3D shape of diesel particulate matter (DPM); we observed that the particles can have sharp jagged appearing edges and consistent with these findings, 2D light microscopy demonstrated that DPM adheres to human lung epithelial cells. Importantly, the slide preparation and confocal microscopy method applied avoids possible alteration to the particles' surfaces and enables colour 3D visualisation of the particles. From twenty-one PM10 particles, the mean (standard deviation) major axis length was 5.6 (2.25) µm with corresponding values for the minor axis length of 3.8 (1.25) µm. These new findings may help explain why air pollution particulate matter (PM) has the ability to infiltrate human airway cells, potentially leading to respiratory tract, cardiovascular and neurological disease.

Exploring the relationship between social deprivation and domestic radon levels in the East Midlands, UK.

The natural radioactive gas radon is widely present in the built environment and at high concentrations is associated with enhanced risk of lung-cancer. This risk is significantly enhanced for habitual smokers. Although populations with higher degrees of social deprivation are frequently exposed to higher levels of many health-impacting pollutants, a recent study suggests that social deprivation in the UK is associated with lower radon concentrations. The analysis reported here, based on published data on social deprivation and domestic radon in urban and rural settings in the English East Midlands, identifies a weak association between increasing deprivation and lower radon areas. This is attributed to the evolution of the major urban centres on low-permeability, clay-rich alluvial soils of low radon potential. In addition, the predominance of high-rise dwellings in towns and cities will further reduce average exposure to radon in populations in those areas.

Full-Scale Fatigue Testing of a Wind Turbine Blade in Flapwise Direction and Examining the Effect of Crack Propagation on the Blade Performance.

In this paper, the sensitivity of the structural integrity of wind turbine blades to debonding of the shear web from the spar cap was investigated. In this regard, modal analysis, static and fatigue testing were performed on a 45.7 m blade for three states of the blade: (i) as received blade (ii) when a crack of 200 mm was introduced between the web and the spar cap and (iii) when the crack was extended to 1000 mm. Calibration pull-tests for all three states of the blade were performed to obtain the strain-bending moment relationship of the blade according to the estimated target bending moment (BM) which the blade is expected to experience in its service life. The resultant data was used to apply appropriate load in the fatigue tests. The blade natural frequencies in flapwise and edgewise directions over a range of frequency domain were found by modal testing for all three states of the blade. The blade first natural frequency for each state was used for the flapwise fatigue tests. These were performed in accordance with technical specification IEC TS 61400-23. The fatigue results showed that, for a 200 mm crack between the web and spar cap at 9 m from the blade root, the crack did not propagate at 50% of the target BM up to 62,110 cycles. However, when the load was increased to 70% of target BM, some damages were detected on the pressure side of the blade. When the 200 mm crack was extended to 1000 mm, the crack began to propagate when the applied load exceeded 100% of target BM and the blade experienced delaminations, adhesive joint failure, compression failure and sandwich core failure.

High resolution 3D confocal microscope imaging of volcanic ash particles.

We present initial results from a novel high resolution confocal microscopy study of the 3D surface structure of volcanic ash particles from two recent explosive basaltic eruptions, Eyjafjallajökull (2010) and Grimsvötn (2011), in Iceland. The majority of particles imaged are less than 100µm in size and include PM10s, known to be harmful to humans if inhaled. Previous studies have mainly used 2D microscopy to examine volcanic particles. The aim of this study was to test the potential of 3D laser scanning confocal microscopy as a reliable analysis tool for these materials and if so to what degree high resolution surface and volume data could be obtained that would further aid in their classification. First results obtained using an Olympus LEXT scanning confocal microscope with a ×50 and ×100 objective lens are highly encouraging. They reveal a range of discrete particle types characterised by sharp or concave edges consistent with explosive formation and sudden rupture of magma. Initial surface area/volume ratios are given that may prove useful in subsequent modelling of damage to aircraft engines and human tissue where inhalation has occurred.

Effects of etching time on alpha tracks in solid state nuclear track detectors.

Solid State Nuclear Track Detectors (SSNTDs) are used extensively for monitoring alpha particle radiation, neutron flux and cosmic ray radiation. Radon gas inhalation is regarded as being a significant contributory factor to lung cancer deaths in the UK each year. Gas concentrations are often monitored using CR39 based SSNTDs as the natural decay of radon results in alpha particles which form tracks in these detectors. Such tracks are normally etched for about 4h to enable microscopic analysis. This study examined the effect of etching time on the appearance of alpha tracks in SSNTDs by collecting 2D and 3D image datasets using laser confocal microscope imaging techniques. Etching times of 2 to 4h were compared and marked differences were noted in resultant track area. The median equivalent diameters of tracks were 20.2, 30.2 and 38.9µm for etching at 2, 3 and 4h respectively. Our results indicate that modern microscope imaging can detect and image the smaller size tracks seen for example at 3h etching time. Shorter etching times may give rise to fewer coalescing tracks although there is a balance to consider as smaller track sizes may be more difficult to image. Thus etching for periods of less than 4h clearly merits further investigation as this approach has the potential to improve accuracy in assessing the number of tracks.

Radium dial watches, a potentially hazardous legacy?

This study re-examines the risk to health from radium ((226)Ra) dial watches. Ambient dose equivalent rates have been measured for fifteen pocket watches giving results of up to 30 µSv h(-1) at a distance of 2 cm taken with a series 1000 mini-rad from the front face (arithmetic mean ambient dose equivalent for pocket watches being 13.2 µSv h(-1)). A pocket compass gave rise to a similar ambient dose equivalent rate, of 20 µSv h(-1), to the pocket watches, with its cover open. Eighteen wristwatches have also been assessed, but their dose rates are generally much lower (the arithmetic mean being 3.0 µSv h(-1)), although the highest ambient dose equivalent rate noted was 20 µSv h(-1). A phantom experiment using a TLD suggested an effective dose equivalent of 2.2 mSv/y from a 1 µCi (37 kBq) radium dial worn for 16 h/day throughout the year (dose rate 0.375 µSv h(-1)). For this condition we estimated maximum skin dose for our pocket watches as 16 mSv per year, with effective doses of 5.1 mSv and 1.169 mSv when worn in vest and trouser pockets respectively. This assumes exposure from the back of the watch which is generally around 60-67% of that from the front. The maximum skin dose from a wristwatch was 14 mSv, with 4.2 mSv effective dose in vest pocket. Radium ((226)Ra) decays to the radioactive gas radon ((222)Rn), and atmospheric radon concentration measurements taken around a pocket watch in a small sealed glass sphere recorded 18,728 B qm(-3). All watches were placed in a room with a RAD7 real-time radon detector. Radon concentration average was 259±9 Bq m(-3) over 16 h, compared to background average over 24h of 1.02 Bq m(-3). Over 6 weeks highs of the order of 2000 Bq m(-3) were routinely recorded when the heating/ventilation system in the room was operating at reduced rates, peaking at over 3000 Bq m(-3) on several occasions. Estimates of the activity of (226)Ra in the watches ranged from 0.063 to 1.063 µCi (2.31 to 39.31 kBq) for pocket watches and from 0.013 to 0.875 µCi (0.46 to 32.38 kBq) for wrist watches. The risk from old watches containing radium appears to have been largely forgotten today. This paper indicates a health risk, particular to collectors, but with knowledge and appropriate precautions the potential risks can be reduced.

A new methodology for cost-effectiveness studies of domestic radon remediation programmes: quality-adjusted life-years gained within primary care trusts in central England.

Radon is a naturally occurring radioactive gas, high levels of which are associated with geological formations such as those found in Northamptonshire and North Oxfordshire in the UK. The UK's National Radiological Protection Board have designated both districts as radon Affected Areas. Radiation levels due to radon, therefore, exceed 200 Bq m(-3), the UK's domestic Action Level, in over one percent of domestic properties. Because of radon's radioactivity, exposure to the gas can potentially cause lung cancer, and has been linked to some 2000 deaths a year in the UK. Consequently, when radiation levels exceed the Action Level, remediation against radon's effects is recommended to householders. This study examines the cost-effectiveness of remediation measures in Northamptonshire and North Oxfordshire by estimating cost per quality-adjusted life-year gained in four Primary Care Trusts, organisations that play a key public health policy role in the UK's National Health Service. The study is the first to apply this approach to estimating the cost-effectiveness of radon remediation programmes. Central estimates of cost per quality-adjusted life-year in the four Primary Care Trusts range from 6143pounds to 10323pounds. These values, when assessed against generally accepted criteria, suggest the remediation programmes in the trusts were cost-effective. Policy suggestions based on the estimates, and designed to improve cost-effectiveness further, are proposed for the four Primary Care Trusts and the UK's National Health Service.

The effects of geology and the impact of seasonal correction factors on indoor radon levels: a case study approach.

Geology has been highlighted by a number of authors as a key factor in high indoor radon levels. In the light of this, this study examines the application of seasonal correction factors to indoor radon concentrations in the UK. This practice is based on an extensive database gathered by the National Radiological Protection Board over the years (small-scale surveys began in 1976 and continued with a larger scale survey in 1988) and reflects well known seasonal variations observed in indoor radon levels. However, due to the complexity of underlying geology (the UK arguably has the world's most complex solid and surficial geology over the shortest distances) and considerable variations in permeability of underlying materials it is clear that there are a significant number of occurrences where the application of a seasonal correction factor may give rise to over-estimated or under-estimated radon levels. Therefore, the practice of applying a seasonal correction should be one that is undertaken with caution, or not at all. This work is based on case studies taken from the Northamptonshire region and comparisons made to other permeable geologies in the UK.

The potential risk from 222radon posed to archaeologists and earth scientists: reconnaissance study of radon concentrations, excavations, and archaeological shelters in the Great Cave of Niah, Sarawak, Malaysia.

This reconnaissance study of radon concentrations in the Great Cave of Niah in Sarawak shows that in relatively deep pits and trenches in surficial deposits largely covered by protective shelters with poor ventilation, excavators are working in a micro-environment in which radon concentrations at the ground surface can exceed those of the surrounding area by a factor of > x 2. Although radon concentrations in this famous cave are low by world standards (alpha track-etch results ranging from 100 to 3075 Bq m(-3)), they still may pose a health risk to both excavators (personal dosemeter readings varied from 0.368 to 0.857 mSv for 60 days of work) and cave occupants (1 yr exposure at 15 h per day with an average radon level of 608 Bq m(-3) giving a dose of 26.42 mSv). The data here presented also demonstrate that there is considerable local variation in radon levels in such environments as these.

A critical comparison of the cost-effectiveness of domestic radon remediation programmes in three counties of England.

Radon remediation programmes in domestic dwellings were carried out in five areas, from three counties of England, and the total costs obtained. A single company, which abided by the Code of Practice of the Radon Council of Great Britain, carried out the remediation. The dose savings from the programmes were calculated and used to estimate the number of lung cancers averted. The data obtained allowed the cost-effectiveness of the remediation programmes in each area to be calculated. The remediation programmes in three areas (Northants 2, 3 and North Oxfordshire) were cost-effective whereas those in two areas (Northants 1 and North Somerset) were not. To be cost-effective, the Northants I and North Somerset areas would need to increase the number of householders that carried out remediation, if they were over the UK Action Level. Health policy makers should concentrate their resources on communities in areas where there is a significant proportion of dwellings above the UK Action Level and where the number of properties being remediated is low.