Urticaceae pollen concentration in the atmosphere of North Western Spain.
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Departamento de Biología Vegetal (Botánica), Universidad de León, León, Spain
Deparatmento de Física, Universidad de León, León, Spain
Ana Maria Vega-Maray   

Departamento de Biologia Vegetal (Botanica), Facultad de Ciencias Biologicasy Ambientales, Universidad de Leon. Campus de Vegazana, 24071 Leon, Spain
Ann Agric Environ Med. 2003;10(2):249–255
Plants of the Urticaceae family can develop into a pest on soils enriched with nitrogen. Urticaceae pollen is a biohazard because it elicits severe pollinosis. Pollen grains were sampled by using a Lanzoni seven-day-recording trap from February 1995-December 2000 in the atmosphere of the city of Ponferrada (Leon, North Western Spain). The Spearman test was used to analyse the statistical correlation between Urticaceae pollen and certain meteorological factors in different main pollination periods. Maximum values are reached in June and July, minimum levels are recorded in January and December. The parameters bearing the greatest positive influence on the occurrence of Urticaceae pollen grains are: temperature (maximum, minimum and mean), humidity (absolute, wet-bulb temperature, dew point and mixing ratio) and south western wind direction; negative parameters are: relative humidity, rainfall and period without wind. The highest correlation coefficients were obtained with temperature and wet-bulb. Absolute humidity and wet-bulb temperature yielded better correlation than relative humidity; hence, these two parameters must be included in this type of study. The use of one main pollination period or another in statistical analysis has an influence on the coefficient value. The behaviour of the pollen grains in the atmosphere during the year also influences the results.