Ongoing monitoring of outdoor aeroallergen levels has regularly provided information that varies, sometimes significantly, from that of previous years. Using results of 22 years and 30 sites of controlled monitoring by ARL using our protocol and self-sourced funding, seasonal differences are investigated to quantify and qualify annual and spatial variances.
The investigation of variances was performed using various statistical analysis and data-mining approaches. Key events of the annual seasons--such as season start and season end--were identified, and their temporal variances were compared for each genus of interest in each location. Similarities and differences in these variances between genera were identified. Similarities and differences in these variances between locations were also identified.
Start dates and end dates for the pollination season of various genera vary annually by up to a month. The number of seasonal peaks within a genus, also varies in number annually. The timing of seasonal events for some genera vary in a similar way in a given year; others vary in an opposite direction in the same year. The timing of events for locations near each-other are not the same, but the annual variances are similar.
The variance of pollination seasons from year to year is significant, and supports the need for continued controlled data collection to monitor and quantify these changes. It is important that such variances, or steps to mitigate them, are taken into account in any practises that depend on or are affected by outdoor allergens.