stigma and pollen surfaces. Cytochemical reactions are responsible for pollen binding to a specific stigma. Allergic diseases are considered to be one of the most important contemporary public health problems affecting up to 15–35% of humans worldwide. There is a body of evidence suggesting that allergic reactions induced by pollen are on the increase, particularly in highly industrial countries. Fungal spores Fungi, a major element of atmospheric bioaerosols, are capable of existing and surviving in the air for extended periods of time. Both the spores and the mycelium may be dangerous for people suffering from allergies, causing various health issues including asthma. Apart from their negative impact on human health, atmospheric fungi may be dangerous for plants as sources of infection. Moreover, fungal organisms may be capable of creating additional toxins that are harmful to humans and animals, such as endotoxins or mycotoxins. Considering this aspect, aeromycological research is considered capable of predicting future symptoms of plant diseases in both crops and wild plants. Fungi capable of travelling extensive distances with wind despite natural barriers, such as tall mountains, may be particularly relevant to understanding the role of fungi in plant disease. Notably, the presence of numerous fungal organisms pathogenic to plants has been determined in mountainous regions. A wealth of correlative evidence suggests asthma is associated with fungi and triggered by elevated numbers of fungal spores in the environment. Intriguing are reports of thunderstorm asthma. In a now classic study from the United Kingdom, an outbreak of acute asthma was linked to increases in Didymella exitialis ascospores and Sporobolomyces basidiospores associated with a severe weather event. Thunderstorms are associated with spore plumes: when spore concentrations increase dramatically over a short period of time, for example from 20,000 spores/m3 to over 170,000 spores/m3 in 2 hours. However, other sources consider pollen or pollution as causes of thunderstorm asthma. Transoceanic and transcontinental dust events move large numbers of spores across vast distances and have the potential to impact public health, and similar correlative evidence links dust blown off the Sahara with pediatric emergency room admissions on the island of Trinidad. Pteridophyte spores Pteridophytes are vascular plants that disperse spores, such as fern spores, Pteridophyte spores are similar to pollen grains and fungal spores, and are also components of aeroplankton. Fungal spores usually rank first among bioaerosol constituents due to their count numbers which can reach to between , while pollen grains