Representative seasonal variation of NDVI measurements for 2007–2008 in the Heraklion-Prefecture.

<p>NDVI values follow a 15 or 16 days temporal resolution. Figure was generated using ArcGIS v.8.0 and NDVI values are freely available from the MODIS web (<a href="http://modis.gsfc.nasa.gov/" target="_blank">http://modis.gsfc.nasa.gov/</a>).</p

Description of models used for allergy description.

<p>In the upper part of the Table the Akaike Information Criterion (AIC) and the Mean Absolute Error (MAE) are presented. In the lower part, the corresponding coefficients for the different retained variables for each model are shown. Significant values for the retained model are shown in bold. Abbreviations: ndvi, Normalized Difference Vegetation Index; tmean, mean daily temperature; tmax, maximum daily temperature; rain, daily rainfall; we, wind eastness. Squares of each factor are represented with the ² symbol, interactions are represented with the × symbol, in column 1. For the retained NT model (in bold) the most significant retained parameters are shown in bold characters.</p><p>Description of models used for allergy description.</p

Graphical presentation of the frequency of patients from the regional area of Heraklion, positive for specific IgE, refered to the University Hospital of Heraklion (solid line) and model fit of the NT Model (dotted line).

<p>Graphical presentation of the frequency of patients from the regional area of Heraklion, positive for specific IgE, refered to the University Hospital of Heraklion (solid line) and model fit of the NT Model (dotted line).</p

Upper Panels.

<p>Predictive value of the retained NT model. Employing a leave-one-out procedure, we attempted to identify whether our models could predict the frequency of emergency department (ED) visits in the metropolitan area of Heraklion. The predictive ability of the NT model, taking into account the ground temperatures (A) was very good, while the SAT model (B), integrating satellite temperature measurements was less performant. Periods refere to half month time-intervals, with the first referring to September 1–15 2007. Lower Panels. Validation of the NT model for severe allergy prediction. In order to validate our NT Model we analyzed a second data-set for the Heraklion metropolitan area (2009–2010) using the same model averaging technique and using the same environmental/meteorological parameters (NDVI, temperature; NT model). Development of the new NT model, based on the same base variables presented a very good model fit both at the Heraklion (C) and at the Chania area (D).</p

Graphical presentation of the frequency of emergency department (ED) visits at the Heraklion metropolitan area (solid line) and model fit of the NT Model, that is derived from NDVI and temperature (dotted line) (A) and the SAT Model Assemblage, from NDVI and satellite collected Land Surface Temperature (B).

<p>See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121475#sec002" target="_blank">Material and Methods</a> for the development of the models. It should be noted that while the raw output of the models is pi, i.e. the proportion of the total population that performed ED visits, results are presented as counts (pi × N), for ease of interpretation in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121475#pone.0121475.g002" target="_blank">Fig. 2</a> and subsequent Figs. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121475#pone.0121475.g003" target="_blank">3</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121475#pone.0121475.g004" target="_blank">4</a>.</p