Jane Hitchins

A pilot investigation into associations between indoor airborne fungal and non-biological particle concentrations in residential houses in Brisbane, Australia

Indoor air contains a complex mixture of bioaerosols such as fungi, bacteria and allergens, as well as non-biological particles including products from various combustion processes. To date little work has been done to investigate the interactions and associations between particles of biological and non-biological origin, however, any occurring interactions could affect pollutant behaviour in the air and ultimately the effect they have on health. The aim of this work was to examine associations between the concentration levels of airborne particles and fungi measured in 14 residential suburban houses in Brisbane. The most frequently isolated fungal genus was Cladosporium, Curvularia, Alternaria, Fusarium and Penicillium. The average outdoor and indoor (living room) concentrations of fungal colony forming units were 1133+/-759 and 810+/-389, respectively. Average outdoor and indoor (normal ventilation) concentrations of submicrometre and supermicrometre particles were 23.8 x 10(3) and 21.7 x 10(3) (particles/cm(3)), 1.78 and 1.74 (particles/cm(3)), respectively. The study showed that no statistically significant associations between the fungal spore and submicrometre particle concentrations or PM(2.5) were present, while a weak but statistically significant relationship was found between fungal and supermicrometre particle concentrations (for the outdoors R(2)=0.4, P=0.03 and for a living room R(2)=0.3, P=0.04). A similarity in behaviour between the submicrometre particle and fungal spore concentrations was that the fungal spore concentrations were related directly to the distance from the source (a nearby park), in a very similar way in which the submicrometre particles originating from vehicle emissions from a road, were dependent on the distance to the road. In the immediate proximity to the park, fungal concentrations rose up to approximately 3100 CFU/m(3), whereas for houses more than 150 m away from the park the concentrations of fungi were below 1000 CFU/m(3). Recommendations have been provided as the future study designs to gain a deeper insight into the relationships between biological and non-biological particles.

Determination of average emission factors for vehicles on a busy road

Abstract In this paper, the CALINE4 software package, designed for calculation of concentrations of carbon monoxide near a busy road, is adapted for the analysis of aerosols of fine and ultra-fine particles, generated by vehicles on the road. A scaling procedure of the CALINE4 package is developed and justified. A new efficient method of determination of the average emission factor for fine particle emission from the average fleet (one average vehicle) on a given road is also developed. This method is based on measurements of the average particle number concentration at just one point near the road. An example of a specific road in the Brisbane area, Australia, is considered. The average emission factor for vehicles on this road is calculated to be ∼4.5×1014 particle/vehicle/mile. The obtained scaling coefficient is shown to be correct, and the procedure is directly applicable for the analysis of an arbitrary road with different types of vehicles and their average speed. Good agreement between the experimental results and the predicted theoretical dependencies of concentration on distance from the road clearly confirms the applicability of the CALINE4 package for the analysis of propagation of fine particle aerosols from a busy road. Statistical analysis of the experimental and theoretical results demonstrates that the concentration of fine and ultra-fine particles approximately reduces as a power law in distance from the road.

Experimental Deposition of Environmental Tobacco Smoke Submicrometer Particulate Matter in the Human Respiratory Tract

Measurements of 15 nonsmokers and 3 smokers breathing environmental tobacco smoke (ETS), were conducted to study particle deposition within the human respiratory tract. The subjects inhaled ETS of count median diameter (CMD) of about 0.2 micron and geometric standard deviation (GSD) of 1.7 The particle size distribution in the submicrometer range in the inhaled and exhaled air from the subjects was measured using a scanning mobility particle sizer (SMPS). A deposition of 56.0 +/- 15.9% was observed for nonsmokers while breathing ETS through the nose and 48.7 +/- 11.6% while breathing ETS through the mouth. One individual tested four times gave an average deposition of 57.4 +/- 11.5%, providing an indication of intraindividual variation. Such a variation is expected since the breathing rate was not controlled in order that an indication of the deposition experienced on a day-to-day basis could be obtained. For nonsmokers the deposition while breathing through the mouth was lower than through the nose and the variability within the measurements was also lower for mouth breathing. The latter could be due to the variation in individual size and shape of the nasal passage. Smokers had, on average, a higher rate of deposition but also a higher interindividual variability making it difficult to draw conclusions with respect to the affect of smoking on ETS particle deposition. The average deposition of the three smokers was 65.3 +/- 24.1% for nasal breathing and 66.1 +/- 17.6% for mouth breathing.

Elemental composition of combustion emissions from spark ignition vehicles

In petrol engines, solid particle phases are formed as a result of incomplete combustion. In emissions from combustion processes such as petrol, natural gas or diesel, concentration of particles smaller than 1 µm could be several orders of magnitude higher than those which are larger than 1 µm. Due to their physical properties, submicrometer particles have a high probability of deposition in the deeper parts of the respiratory tract. It is known that petrol particles are mutagenic and carriers of hydrocarbons (and other compounds) adsorbed on the particulate and as a result represent a serious health hazard if inhaled. The present paper reports on some measurements of particle size distribution and composition of the bulk aerosol, as well as on morphological and elemental information from individual particles. The study was performed on non-diluted petrol exhaust obtained under different engine operation conditions. The bulk aerosol chemistry study has been performed. The concentrations of the following trace elements were measured: Boron, Calcium, Titanium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Cadmium, Barium, and Lead. The petrol particles have been found to be spherical. The most abandon elements were Fe, Ca, and Zn that have their origin from the additives in lubricating oil. It is interesting to note that although particle concentrations increased for 3 orders of magnitude from 40 to 120 km/h, emissions of metals did not significantly increase. This would indicate that most of the particle emission at higher loads comes from the unburned fuel and consists mainly of carbon either in elemental or organic form.