Hay fever, majorly known as allergic rhinitis, is a common condition that shows signs and symptoms similar to a cold with sneezing, congestion, runny nose and sinus pressures. Hay fever is caused by an allergic response to airborne substances, such as pollen - unlike a cold which is caused by a virus. The time of year in which you get hay fever depends on what airborne substance you are allergic to.
Although hay fever and allergic rhinitis have the same meaning, most lay people refer to hay fever only when talking about an allergic reaction to pollen or airborne allergens from plants or fungi, and understand allergic rhinitis as an allergy to airborne particles, such as pollen, dust mites or pet dander which affect the nose, and maybe the eyes and sinuses as well. As with other allergies, hay fever symptoms are a result of your immune system mistaking a harmless substance as a harmful one, and releasing chemicals that cause the symptoms. The International Study of Asthma and Allergies in Childhood Phase Three covered all the major regions of the world
The 13- to 14-year age group involved 670 242 children in 232 centres in 97 countries, and the mean response rate was 91.1%. The 6- to 7-year age group involved 388 811 children in 144 centres in 61 countries and the mean response rate was 84.5%. In four centres data were available only for the 6- to 7-year age group. In total, the survey involved 1 059 053 children from 236 centres in 98 countries. The percentage of cases effected by hay fever per year is 7.2%