A new study found that people living nearest the equator have higher rates of allergies and asthma.
Geography and sunlight could be to blame, according to the study published in the The researchers believe that the varying allergy rates could be due to the effect of UV-B rays on the body's vitamin D production.
Annals of Allergy, Asthma & Immunology.
The researchers, from the American College of Allergy, Asthma and Immunology, analyzed data from a larger study involving 5,729 participants. Of these, 1,397 visited clinics for allergy testing. The participants were children when the study began in 1968, and were in the study until 2004, with follow-up surveys conducted in 1974, 1981, 1992, and 2004.
Increased Allergy Rates Found
It was found that participants whose addresses were closest the equator – resulting in high UV-B exposure – had an increased likelihood of developing hay fever,
, skin sensitivity to household allergens such as mold and dust mites, and asthma.
Vicka Oktaria, lead study author, wrote: "UV-B rays exposure is higher for people living in areas closer to the equator. This increase in UV-B may be linked to vitamin D, which is thought to modify the immune system. These modifications can lead to an elevated risk of developing allergy and asthma."
Source: Everyday Health