A large number of plants exist on Earth. Geographical location, soil composition, and climate are the main natural factors associated with plant distribution and botanical biodiversity. Speciation and hybridization are responsible for the existence of different plant varieties of the same species, which often produce pollen with allergenic capacities composition. Pollen is responsible for seasonal allergies worldwide.
The topic of how human activities impact pollen is complex. Urbanization alters the distribution of native plants by reducing their ecological niches. On the contrary, plants that produce highly allergenic pollen are often introduced in urban areas due to landscaping practices.
Invasive plants are also accidentally introduced in ecosystems, and they slowly replace native plants. For example, short ragweed (Ambrosia artemisiifolia), a weed native from the USA that produces highly allergenic pollen, was introduced in Europe years ago, and now this pollen is responsible for seasonal allergies in many European countries.
“Global warming”, another phenomenon associated with human activities, also affects plant biodiversity. A global increase in temperature is altering the geographical distribution of many plant species and their pollination patterns.
In addition, to the effect of human activities on pollen previously mentioned, this phenomenon might also impact pollen directly. For example, many observations indicate that the increasing levels of air pollution associated with urbanization and extensive use of fossil fuels augment the allergenic potential of pollen derived from different plants. Other observations suggest that pollen exposed to high levels of air pollution have greater inflammatory properties than pollen present in non-polluted areas.
In summary, the effect of human activities on plant biodiversity, pollination patterns, and pollen allergenic potential has been documented. The potential impact of this phenomenon on human health is under investigation.
Allergists/immunologists should be aware of the potential impact of human activities on pollen, and that their patients could perhaps experience non-expected exacerbations of their allergy symptoms in the future. Companies that manufacture pollen allergen extracts to diagnose and treat allergic diseases should take the correct measures to assure that the appropriate pollen is collected for the intended purpose.