Hypersensitivity towards any foreign material or particle is known as

$A$ person shows strong unusual hypersensitive reactions when exposed to certain substances present in the air. Identify the condition. Name the cells responsible for such reactions. What precaution should be taken to avoid such reactions?

Allergy is due to the release of chemicals like $...$ and $...$ from the $...$ cells.

Which chemical is used for the treatment of allergy?

$Hay \, fever$ is a type of which disease?

Many people suffer from which system-related problem due to pollen grains of many species?