Aerobiological study of Chenopodiaceae and Amaranthaceae in the Mediterranean area of southwestern Spain.

The study area is characterized by a maritime Mediterranean climate, abundant presence of Chenopodiaceae in the vegetation, and a high incidence of pollinosis caused by the pollen of this family. A Hirst-type sampler was used to determine pollen concentrations in the air of the city of Huelva during 3 consecutive years (1995-1997). The total annual amount of Chenopodiaceae-Amaranthaceae pollen was between 10.59% and 6.28% of the pollen spectrum of the city, depending on the year. The annual pattern of variation in pollen concentration (5-day means) was very similar in the 3 years, and no statistically significant differences were found between years. This pattern is characterized by concentrations not exceeding 20 grains/m3 between April and the beginning of August, with an obvious seasonal variation in the second half of August and September, when the 5-day mean concentrations exceeded 40 grains/m3 and the daily maxima exceeded 100 grains/m3. This coincided with the flowering of most of the species in the group. The meteorological parameters with a statistically significant effect on daily pollen concentration during the pollen season (August 15 to September 20) included mean temperature and south wind (positive correlations) and relative humidity of the air (negative correlation). The highest intradiurnal concentrations were found between 10:00 a.m. and 5:00 p.m.