Bioaerosols in urban environments: Trends and interactions with pollutants and meteorological variables based on quasi-climatological series.

Pollen grains emitted by urban vegetation are the main primary biological airborne particles (PBAPs) which alter the biological quality of urban air and have a significant impact on human health. This work analyses the interactions which exist between pollen-type PBAPs, meteorological variables, and air pollutants in the urban atmosphere so that the complex relationships and trends in future scenarios of changing environmental conditions can be assessed. For this study, the 1992-2018 pollen data series from the city of Granada (southeast Spain) was used, in which the dynamics of the total pollen as well as the 8 main pollen types (Cupressaceae, Olea, Pinus, Platanus, Poaceae, Populus, Quercus and Urticaceae) were analysed. The trend analysis showed that all except Urticaceae trended upward throughout the series. Spearman's correlations with meteorological variables showed that, in general, the most influential variables on the pollen concentrations were the daily maximum temperature, relative humidity, water vapor pressure, global radiation, and insolation, with different effects on different pollen types. Parallel analysis by neural networks (ANN) confirmed these variables as the predominant ones, especially global radiation. The correlation with atmospheric pollutants revealed that ozone was the pollutant with the highest influence, although some pollen types also showed correlation with NO2, SO2, CO and PM10. The Generalized Linear Models (GLM) between pollen and pollutants also indicated O3 as the most prominent variable. These results highlight the active role that pollen-type PBAPs have on urban air quality by establishing their interactions with meteorological variables and pollutants, thereby providing information on the behaviour of pollen emissions under changing environmental conditions.

Parietaria major allergens vs pollen in the air we breathe.

BACKGROUND: Parietaria and Urtica are the genera from the Urticaceae family more frequent in Mediterranean and Atlantic areas. Moreover, both genera share pollination periods, and their pollen (of the main species) is so similar that there is no aerobiological evidence of the proportion of each of them in the airborne pollen identification, except in the case of U. membranacea. However, Parietaria is one of the most important causes of pollinosis and Urtica is not. Our aim is determine if airborne Urticaceae pollen concentrations show the aerodynamics of the two major allergens of Parietaria (Par j 1 and Par j 2) as well as the allergen distribution in the different-sized particles. METHODS: The air was sampled during the pollination period of Urticaceae using Hirst Volumetric Sampler and Andersen Cascade Impactor in two cities of Southern Spain (Córdoba and Granada). The samples were analysed by the methodology proposed by the Spanish Aerobiology Network (REA) and the minimum requirements of the European Aeroallergen Society (EAS) for pollen, and by ELISA immunoassay for allergens. RESULTS: The patterns of airborne pollen and Par j 1-Par j 2 were present in the air during the studied period, although with irregular oscillations. Urticaceae pollen and Par j 1-Par j 2 allergens located in PM2.5 showed positive and significant correlation during the period with maximum concentrations (March to April). CONCLUSION: Parietaria aeroallergens show similar pattern of Urticaceae airborne pollen. Urticaceae pollen calendar is as a good tool for allergy prevention. On the other hand, important concentrations of Par j 1 and Par j 2 were located in the breathable fraction (PM2.5), which could explain the asthmatic symptoms in the allergic population to Parietaria.

Assessing allergenicity in urban parks: A nature-based solution to reduce the impact on public health.

Urban parks play a key role in the provision of ecosystem services, actively participating in improving the quality of life and welfare of local residents. This paper reports on the application of an index designed to quantify the allergenicity of urban parks in a number of Spanish cities. The index, which records biological and biometric parameters for the tree species growing there, classifies parks in terms of the risk they pose for allergy sufferers, graded as null, low, moderate or high. In this initial phase, the index was applied to 26 green areas in 24 Spanish cities; green areas varied in type (urban park, historical or modern garden, boulevard, square or urban forest), size 1-100 ha), geographical location, species richness, number of trees and tree density (number of trees / ha.). The data obtained were used to calculate the percentage of allergenic species in each park, which varied between 17-67%; density ranged from 100 to 300 trees/ha. The index values recorded ranged from a minimum of .07 to a maximum of .87; a significant correlation was found between index value and both number of trees and tree density. Taking an index value of .30 as the threshold considered sufficient to trigger allergy symptoms in the sensitive population, 12 of the parks studied may be regarded as unhealthy at any time of the year. Corrective measures to mitigate the impact of pollen emissions include the implementation of nature-based solutions at various levels: planning and design, handling and management, and strengthening of urban green-infrastructure elements. The index proved to be a useful tool for environmental analysis, and complies with the principles of portability and scalability central to current and horizon scientific research.

Characterization of Allergen Emission Sources in Urban Areas.

Pollen released by urban flora-a major contributor to airborne allergen content during the pollen season-has a considerable adverse impact on human health. Using aerobiological techniques to sample and characterize airborne biological particulate matter (BPM), we can identify the main species contributing to the pollen spectrum and chart variations in counts and overall pollen dynamics throughout the year. However, given the exponential increase in the number of pollen allergy sufferers in built-up areas, new strategies are required to improve the biological quality of urban air. This paper reports on a novel characterization of the potential allergenicity of the tree species most commonly used as ornamentals in Mediterranean cities. Values were assigned to each species based on a number of intrinsic features including pollination strategy, pollen season duration, and allergenic capacity as reported in the specialist literature. Findings were used to generate a database in which groups of conifers, broadleaves, and palm trees were assigned a value of between 0 and 36, enabling their allergenicity to be rated as nil, low, moderate, high, or very high. The case study presented here focuses on the city of Granada in southern Spain. The major airborne-pollen-producing species were identified and the allergenicity of species growing in urban green zones was estimated. Corrective measures are proposed to prevent high allergen levels and thus improve biological air quality.

Platanus pollen season in Andalusia (southern Spain): trends and modeling.

Platanus is a major cause of pollen allergy in many Spanish cities. The present paper reports an analysis of Platanus pollen season throughout the Andalusia region (southern Spain), which has among the highest pollen counts and the highest incidence of Platanus-related allergies in Europe. The main aim was to analyze pollen season trends from 1992 to 2010 in Andalusia; models were also constructed to forecast the start of the season. Daily pollen counts were recorded using Hirst-type volumetric spore-traps. Pollen season start-dates were very similar at all sites, usually occurring in March. The pollen season was delayed over the study period. The Pollen-season duration and Pollen index generally increased throughout the study period. The starting date for temperature accumulation was around the 10th February, although the threshold temperatures varied by site. The regional model for Andalusia failed to provide sufficiently accurate results compared with sub-regional or local models. For modeling purposes, three sub-regions are recommended: Inland, East Coast and West Coast.

Tracking Montane Mediterranean grasslands: Analysis of the effects of snow with other related hydro-meteorological variables and land-use change on pollen emissions.

This paper explores the dynamics of temporal evolution of the high mountain Mediterranean grasslands, (Sierra Nevada, Spain SE). The indicator used is the emission of pollen (Pollen Index, PI) with respect to two important aspects: the incidence of the snow dynamic together with other hydro-meteorological parameters, and the changes in land use, which can Influence the evolution of the grasslands throughout time. The results reveal that pollen emissions in the last 25 years have shown a slight downward trend, with large interannual fluctuations, which are a consequence of diverse environmental factors, both general and specific to the area. One of the most influential parameters on pollen concentrations is snow cover, which reinforces the importance of the presence of snow-packs as water resource outside the winter season in the High Mediterranean Mountain environments. The changes in land use experienced in the area are a driver of change, especially due to the losses experienced in the last decades in the preferred habitats for many species of grasses. It can be concluded that the vulnerability of these ecosystems will be affected by an increase in winter temperatures and/or a decrease in rainfall (climate change) and an increase in the intensity of anthropogenic activities on land use. In this context, the PI is shown as a useful indicator of global change given its sensitivity to both anthropic and hydro-meteorological changes. In addition, it has a wide range of spatial detection and discrimination capacity by altitudinal dimensions.