Martin Hooper

Indoor airborne fungal spores, house dampness and associations with environmental factors and respiratory health in children

Children living in a damp house are more likely to suffer from respiratory symptoms and it has been suggested that exposure to fungi is an important contributing factor. However, more knowledge about underlying mechanisms for the association are needed.

Increased risk of allergy in children due to formaldehyde exposure in homes

Background: Formaldehyde levels were measured in 80 houses in the Latrobe Valley, Victoria, Australia. An association between exposure to formaldehyde and sensitization to common aeroallergens has been suggested from animal trials, but no epidemiologic studies have tested this hypothesis.

Size-resolved airborne particles and their morphology in Central Jakarta

Abstract Air pollution in Jakarta, the capital city of Indonesia, has become a serious concern with the potential to affect the health and well-being of its citizens. Since different sources emit particles in different size ranges, understanding the particle size distribution and their morphology is important in setting up effective control and management measures. Airborne particles in central Jakarta were sampled via a size-fractionating cascade impactor, and the mass loading of each fraction determined gravimetrically. The average total mass loading is 120 μg m−3 across the period, April 1994–October 1995. Using an inversion procedure based on a nonlinear iterative method, a bimodal lognormal size distribution was found. The two distribution maxima were centred at approximately 0.6 and 6.3 μm aerodynamic equivalent diameters, respectively. The elemental concentrations were analysed by Inductively Coupled Plasma-Atomic Emission Spectrometry. The crustal elements Al, Si and Ca showed a close association. The distribution pattern for these crustal-related elements suggests that crustal dust is contributing significantly not only to the coarse fraction but also to the fine fraction. The chemical components relating to anthropogenic sources such as Pb, Zn and K tended to accumulate in the fine particle range. Results revealed that Na had a sizeable loading in the coarse fraction, undoubtedly associated with a marine source. Scanning Electron Microscopy combined with an Energy Dispersive X-ray Detector was used for morphological characterisation of individual particles. Traffic-related particles such as carbon-based material from diesel vehicle exhaust and Pb-rich fine particles from combustion of leaded petrol were identified as being particular concerns.

Indoor environmental factors associated with house-dust-mite allergen (Der p i) levels in south-eastern Australian houses

Background Eighty households in the Latrobe Valley, Victoria, Australia, were sampled for house‐dust‐mite allergen (Der p 1). Allergen levels vary greatly between houses within climate regions. The reasons for this are not well understood.

Analysis of ephedrine in ephedra callus by acetonitrile modified capillary zone electrophoresis

A simple method has been developed for the quantitative determination of ephedrine in ephedra callus. The dependence of effective mobility of ephedrine on pH was investigated, and a simulated equation was obtained. The separation was performed in an uncoated capillary and detected at 185 nm. A new Tris-NaOH-H(3)PO(4) run buffer was used and the pH was adjusted to 3.20. To increase the solubility of hydrophobic analytes and improve the separation efficiency, 15% acetonitrile was used in the buffer as a modifier. The content of ephedrine in an ephedra callus sample and an ephedra herba sample were determined with this method, and the result was satisfactory.

LARGE ARTIFICIAL NEURAL NETWORKS APPLIED TO THE PREDICTION OF RETENTION INDICES OF ACYCLIC AND CYCLIC ALKANES, ALKENES, ALCOHOLS, ESTERS, KETONES AND ETHERS

Abstract Artificial neural networks (ANN) with extended delta-bar-delta (EDBD) back propogation learning algorithms were used to predict the retention indices of 184 organic compounds. These compounds include acyclic and cyclic alkanes, alkenes, alcohols, esters, ketones and ethers. The networks architecture and parameters were optimized to give maximum performance. The best network is 2–6–1, the optimum learning epoch is 2000. In the process of the study, cross-validation and leave-20%-out were used. The results show that the prediction performance of ANN operating with such non-linear systems is remarkably good.

Long-term observations of regional aerosol composition at two sites in Indonesia.

Aerosol samples were collected with Gent PM10 stacked filter unit (SFU) samplers at Bukit Tinggi, a mountain site on Sumatra, and at Pontianak, a sea-level site on Kalimantan. The Gent PM10 SFU sampler provides two size fractions: coarse (2–10 μm equivalent aerodynamic diameter (EAD)) and fine (<2 μm EAD). At Bukit Tinggi, 130 SFU samples were taken from April 1996 to August 1999, and at Pontianak, 66 samples from the end of December 1997 to June 1999. All samples were analysed for the particulate mass (PM), black carbon (BC), and up to 47 elements. A combination of particle-induced X-ray emission spectrometry and instrumental neutron activation analysis was used for the multielemental analyses. The average fine-to-coarse ratios were at both sites around 1 for the PM, but above 2 (up to 5) for BC, S, Sb, I and Pb. The median PM concentrations (and interquartile ranges) in the coarse size fraction were 4.8 (3.8–5.6) and 12 (9–14) μg/m3 at Bukit Tinggi and Pontianak, respectively. For the fine fraction, the corresponding numbers were 4.5 (2.6–9.1) and 9.4 (6.5–13) μg/m3. Principal component analysis was applied to the fine fraction data sets in order to identify the contributing sources (source types). At Bukit Tinggi, five components were identified, i.e., a crustal component, a biomass burning component (with loadings of 0.7–0.9 for BC, K, Br, Rb and I), an oil combustion component (with S and V), a pollution component (with Sb and Pb), and a Na component.

Nitrogen Dioxide in Australian Homes: Levels and Sources

Indoor nitrogen dioxide exposure has been associated with respiratory symptoms in children in many studies, but in Australia, levels and sources of nitrogen dioxide in homes have not been well-characterized. Therefore, as part of a larger indoor environmental study, conducted in the Latrobe Valley, Victoria, nitrogen dioxide was monitored using passive samplers in 80 homes. Samples were collected on five occasions over one year. Mean indoor levels were higher than outdoor levels, and a seasonal variation was evident, with highest levels recorded in winter. The overall median level was 11.6 micrograms/m3 (6.0 ppb), ranging from < 0.7 to 246 micrograms/m3 (128 ppb). Major indoor nitrogen dioxide sources were: gas stoves, vented gas heaters, and smoking. Some 67% of variation in indoor nitrogen dioxide levels could be explained by presence of major sources, house age, and outdoor levels. Gas stoves were the main contributors.

Atmospheric particulate matter and polycyclic aromatic hydrocarbons for PM10 and size-segregated samples in Bangkok

Abstract Air samples of particulate matter (PM) with an aerodynamic diameter less than 10 µm (PM10) were collected from six sites in Bangkok, Thailand, using high-volume air samplers. Daily samples were taken at intervals of 12 days from November 1999 to November 2000. Size-selected sampling using a multislit Andersen size-fractionated cascade impactor was undertaken at one site in central Bangkok to identify particulate size distribution. The annual average PM10 concentration at all six sites exceeded the Thailand National Ambient Air Quality Standard (NAAQS) of 50 µg/m3. The daily PM10 concentrations at heavy traffic roadside areas ranged between 30 and 160 µg/m3. The highest PM10 level occurred during the winter period (November–February), which is the dry season. From our results, which are based on a 1-yr survey, it can be observed that the particulate concentrations are associated with traffic volumes and seasonal factors (temperature and rainfall). The relative importance of size fractions in contributing to PM load is presented and discussed. Twenty polycyclic aromatic hydro-carbons (PAHs) associated with PM have been identified and quantified. The summed PAHs based on the 20 species had an average concentration of 60 ng/m3. Benzo(e)pyrene, indeno(123cd)pyrene, and benzo(ghi)perylene were the major compounds with average concentrations of 8, 10, and 13 ng/m3, respectively. Results indicate that more than 97% of PAHs were found in the small particulate size range of <0.95 µm.

Airborne Mould Levels and Related Environmental Factors in Australian Houses

Airborne mould sampling studies were conducted in 40 selected Australian (Latrobe Valley, Victoria) houses. Both total indoor culturable and total mould spore levels were observed to be relatively high with 58% of houses with one or more rooms exceeding 1,000 cfu/m3 and 48% exceeding 10,000 spores/m3, respectively. Median indoor total mould spore levels exceeded total culturable levels by 14-fold in concurrent sampling. An evaluation of the indoor/outdoor ratios of selected genera indicated that 50% of indoor concen trations could be explained by outdoor mould levels. Applying a univariate analysis of variance, significant differences in mould levels associated with a variety of housing characteristics and environmental factors were observed. A house age >20 years and relative humidity ≥ 70% were observed to be signifi cant independent contributing factors to elevated indoor culturable mould levels while similarly these factors with water intrusion through the building envelope gave elevated total indoor mould spore levels.