Summary

This paper reviews the relationships between humidity, house-dust mites and respiratory allergy. In vitro relationship between relative humidity and house-dust mite growth are quite clear cut. In real conditions also, there is a significant association between relative humidity and the presence of live mites. The relevance of house-dust mites for respiratory allergy lies on clinical, physiopathological and mostly on epidemiological data. The latter demonstrate a correlation between exposure to mites and risk of sensitization and development of overt allergic diseases. Lastly, humidity of dwellings is linked to respiratory allergy. These results should lead to building safer dwellings for allergic subjects, or modifying existing dwellings. In this respect, emphasis should be put on a proper ventilation rate and also a proper behaviour of inhabitants in order to minimize humidity production.

Ambrosia pollen is known as an importantallergen in North America, and more recently in someEuropean countries. From 1989 to 1995, the Ambrosia pollen levels detected at the stationsmonitored by the Aerobiological Network of Catalonia(Xarxa Aerobiològica de Catalunya, XAC) wereinsignificant. In 1996, a considerable althoughtemporary increase in the concentration of this pollenwas detected in the atmosphere over Girona, Barcelona,Bellaterra, Manresa, and Tarragona. Most of the Ambrosia pollen collected in 1996 was concentrated ina single day. Its appearance on that day wasattributed to long range transportation, caused byunusual conditions of atmospheric circulation, fromthe Lyon region in France where the species isabundant. This is the only day where concentrations ofAmbrosia pollen that may be dangerous to humanhealth have been reached.

Ambrosia coronopifolia is the most abundantspecies of the genus in Catalonia, and although rare,its expansion is favoured by the fact that it growsthrough rhizomes and sprouts easily. It is, therefore,important to monitor the growth of its population andthe release of its pollen in order to predict theappearance of pollen levels that may precipitateallergic symptoms.

Summary

For allergological purposes it is of interest whether the number of allergenic pollen will change in a significant order. Linear regression and correlation of different pollen types show that the annual totals of most of the allergenic pollen remain constant. None of the pollen grains show distinct and significant disappearance, but four types show significant increase of annual totals: Varia, Sambucus, Cupressaceae and Rubicaea. Pollen of Cupressaceae and Castanea fairly will become of more allergological interest within the next years, if the upward-trend should prove to be continous. No significant change was found in the number of the investigated spores.

The air mycoflora of six indoor environments in Madras city (India) has been investigated by sampling air with an Andersen sampler and a Burkard personal sampler. Forty-eight species assignable to 24 genera were recorded by Andersen sampler. Spores belonging to 14 genera in addition toPenicillium andAspergillus were identified from Burkard trap slides. Species ofAspergillus, Penicillium, Mucor andRhizopus were most frequently isolated in considerable numbers. As a single genusAspergillus ranked first followed byPenicillium at some sites, andCladosporium at some other sites. The predominance ofPenicillium andAspergillus was also confirmed by Burkard trap data. Spores belonging toGanoderma, Nigrospora, Epicoccum, andTetraploa were recorded only by Burkard sampler, thereby suggesting the necessity of using two complimentary spore traps, cultural and non-cultural, in any aerobiological investigation.

First data from a pollen survey carried out in the city of Murcia (SE Spain) are given in this paper. Using a Burkard Volumetric Spore Trap, daily slides were prepared and 80 pollen types belonging to 51 families andAlternaria spores were identified and counted. Special attention was paid to 14 relevant taxa: Cupressaceae,Pinus, Genisteae,Olea, Morus, Acer, Platanus, Plantago, Quercus, Urticaceae, Poaceae, Chenopodiaceae,Artemisia andAlternaria. The main sources of airborne particles wereAlternaria (27.7%), Cupressaceae (13.5%),Olea (9.36%), Chenopodiaceae (8.31%) and Urticaceae (5.8%). Annual variations in pollen abundance and length of the flowering seasons are given for individual species and are related to environmental factors. Results indicate a main pollen season from March to June and a second minor season in September to October. The relatively high concentrations of Genisteae and the appearance of anArtemisia winter season were noted.

The concentration and species composition of viableGram-negative bacteria was determined in samples of coniferous wood (Scots pine) and deciduous wood (European beech), and in air samples taken during the processing of these woods in sawmills. The concentration of Gram-negative bacteria in the sapwood of pine logs ranged from 1.0 × 10¹ to 6.2 × 10⁴ CFU/g. Their concentration in the air of the pine processing sawmill was within a range of 1.0 × 10²–6.3 × 10² CFU/m³. Concentration of Gram-negative bacteria in the sapwood of beech logs was similar to that in the sapwood of pine logs, ranging from 1.0 × 10¹ to 4.6 × 10⁴ CFU/g. However, the concentration of these bacteria in the air of a beech processing sawmill was within a range of 7.8 × 10³–1.3 × 10⁴ CFU/m³, being significantly higher than in a pine processing sawmill. Enterobacteriaceae strains, mostly Enterobacter spp. and Rahnella spp., made up 70–75% of Gram-negative bacteria isolated from pine and beech wood and from the air pollutedwith sawdust from these woods. The aerial exposure to Gram-negative bacteria possessing endotoxic andallergenic properties poses potential risk ofoccupational respiratory disorders among sawmillworkers, in particular those processing beech wood.

Ragweed pollen have been monitored since 1976 inVienna. Since 1984, the outdoor patients of theallergy department of the ear-nose-and-throatUniversity Clinic underwent both Skin Prick Test andRAST/CAP test with a standard series of commoninhalant allergens, ragweed (Ambrosia elatiorL.) included. Both the ragweed counts and the number of positiveRAST results showed a significant increase by time.Furthermore, a clear correlation between the number ofairborne pollen and the percentage of positiveRAST/CAP results is evident.The immune-response in the Viennese population ofatopic subjects is dependent on the amount of inhaledpollen.

Summary

Gramineae and Urticaceae seasonal variations and diurnal rhythms for Derby in 1986, 1987 and 1988 are shown and discussed.

The time of highest hourly concentration of Gramineae for Derby in June was 1900 hours. Maximum hourly counts for June of Urticaceae pollen occurred between 1400 and 1600 hours.

Urticaceae has a second period of high concentration in August. Gramineae and Urticaceae pollens from 1969–1990 show no significant long term trends.

Most statistical analyses are done under the premisethat the population distribution of the phenomenaunder study is normally distributed. In order to findthe best probability distribution (also called theprobability density function) that should be appliedto aerobiological data (in order to find the mostadequate error probability to apply in any hypothesistesting), the whole airborne pollen data set of 11years in Montréal (comprising 4070 days of mainpollination periods) was subjected to a distributionmodel analysis. When considered as a time-series(i.e. keeping successive days on the X-axis) the PDFthat best represents the aerobiological data set isindeed the Normal distribution. However, when onlythe frequency of different atmospheric concentrationsis used (i.e. having a number of occurrences on theY-axis), as would be done for a site-specific insteadof a time-specific distribution, the PDF is notnormally distributed. The resulting distributionappears log-normal to the eye, but the resultingfrequency distribution is in fact only asymptoticallylog-normal. It is in fact a Gamma distribution G(β, a). The two parameters of the Gammadistribution are its shape parameter (β) and itsscale parameter (a). In our case, β was 0.08and α was 0.002. The PDF is right-skewed when definedover the positive axis 0 < X < ∞. Althoughlog-normal distribution is the most used datatransformation for parametric statistical analyses inaerobiology, it seldom accurately describes the lowerend of the observations near the minimum detectablelimits. Better aerobiological inferences could beobtained by using a Gamma PDF for calculatingthreshold probabilities.