Progressive pollen calendar to detect long-term changes in the biological air quality of cities in the Madrid Region, Spain

Abstract

Rhinoconjunctivitis and allergic asthma are among the most frequent diseases in the world, and pollen is their main cause. The incidence of respiratory allergic diseases is expected to grow in the coming years as a consequence of ambient pollution, changes in land use and land cover in cities, and climate change. In this context of global change, the environmental information provided by monitoring and warning networks must be as updated as possible in order to be useful to the end users in the cities. The Madrid Autonomous Region (central Spain) has suffered a noticeable change in its land-use configuration in recent decades and a significant upward temperature trend throughout the entire area. We found that the aerobiological stations in the Madrid Region Palynological Network, covering the most populated cities of this region in central Spain, registered a marked shift towards a greater airborne pollen load of the most abundant tree pollen taxa (Cupressaceae, Platanus and Quercus, but also Pinaceae, Olea and others). These temporal changes are very evident in the pollen calendar for two periods, 1994–2004 (past) and 2012–2022 (present), pointing to changes in the phenology and intensity of the airborne pollen dynamic in cities in the Madrid Region. Based on these findings, we present a technical proposal to the Madrid Region Palynological Network to generate pollen calendars for each city using the reference period of the last ten years, and to update this information every three years. Finally, we propose the latest pollen calendar for all the aerobiological stations in the Madrid Region Palynological Network for the last ten years (2013–2022), which is considered the reference aerobiological information at present for one of the most populated metropolitan areas in Europe.