## 5 Discussion
This agrees with the results of this work, where different models are shown for different locations and years. Today, air pollution and other essential factors such as concomitant diseases, socioeconomic factors, and other environmental factors such as climate contribute to geographical differences in the prevalence of allergic conjunctivitis. Air pollution contributes to the exacerbation of the symptoms of this pathology but also to the increased incidence of its severe manifestations [31]. In the study conducted in Japan [31], both PM\({}_{10}\) and NO\({}_{2}\) showed a statistically significant association with the prevalence of vernal keratoconjunctivitis, one of the most severe forms of ocular allergy, and which presents with bilateral inflammation of the conjunctiva, and occurs more frequently in children and in the spring and autumn months [31; 32]. Furthermore, in that study, atopic keratoconjunctivitis, another severe ocular allergy that, like the previous one, threatens vision and presents with similar clinical manifestations, showed a significant relationship with NO\({}_{2}\) levels. Seasonal allergic conjunctivitis was associated with PM\({}_{10}\) and oxidants (NO\({}_{2}\) and O\({}_{3}\), both recognized as essential pollutants associated with allergies), albeit with a low relative contribution, considering the high prevalence of seasonal allergic conjunctivitis. Therefore, it can be stated from that study that air pollution may particularly affect severe forms of ocular allergic diseases [31]. Comparatively, in the present study, as could be seen, O\({}_{3}\) is the most frequently included in the equations found for allergic conjunctivitis, followed by NO\({}_{2}\) and particle PM\({}_{10}\), which confirms the importance of these three air pollutants to allergic conjunctivitis, as in [31]. According to some authors [33], it would be convenient to analyze this interrelation in the pollination seasons (within the main pollination period) of the species under study to avoid the possible masking of the interrelation between the independent variables by the most stable variables in their concentrations throughout the year, such as atmospheric pollutants. An analysis of meteorological parameters should also be carried out, together with the variables included in this work, since they have an essential influence on pollination and act synergistically on pollen grains and all types of aerobiological particles and pollutants in the atmosphere [9; 34]. The annual variation in the models fitted for each season in this study indicates the possible influence of time-varying meteorological parameters. The interaction between pollen and pollutants also manifests itself in the form of other pathologies such as asthma, as shown in the cohort study conducted by [PERSON], [PERSON] et al. [33], which analyses the evolution of asthmatic patients allergic to grass and olive tree pollens (with positive sensitization in the skin test), with a mild to moderate clinical evolution, during the _Paceae_ and _Olea_ pollination season, in two Spanish cities, one highly industrialized, Puertollano, and the other with a lower concentration of atmospheric pollutants, Ciudad Real. In this study, it is concluded that patients living in Puertollano have a worse clinical evolution of asthma, significantly related to environmental pollution, due to the presence of PM\({}_{10}\), NO\({}_{2}\), SO\({}_{2}\), and O\({}_{3}\) in the atmosphere, and evidenced by an increase in the severity of symptoms and in the consumption of medication. This study is of special interest, as the clinical course of asthmatic patients with increased severity of their disease is usually analyzed [33]. Also, in relation to asthma, the study by [PERSON], [PERSON] et al., using a Brown Norway (BN) rat model of a house dust mite (HDM) allergy, indicates that an exacerbation of the symptoms associated with asthma may occur because of pre-exposure of asthmatic patients to the metallic components of residual oil fly ash particles (ROFA).