Raising sea levels, glaciers retreat, altered patterns of agriculture, climate change - global warming is also making increasing number of people susceptible to allergies, say experts warning that the trend is assuming worrying proportions.

Allergies are fast emerging as disease of the 21st century, warns the World Allergy Organisation (WAO).

Incidence of allergy and associated diseases as asthma and rhinitis or inflammation of internal nasal areas, is on the rise. The problem may assume alarming proportions with decline in the number of health care professionals trained in diagnosis and treatment of allergy. Globally 2.5 lakh people die of asthma annually.

"Allergy is a major problem for the 21st century, and this problem is predicted to worsen as this century moves forward," the WAO says.

It says that an estimated 300 million people worldwide have asthma. Around 400 million people suffer from allergic rhinitis.

"A field study conducted in four major cities of India showed the overall presence of asthma in 2006 to be 2.38 per cent.," report by the WAO says.

"Higher standards of hygiene in the West and elimination of diseases through public health measures has led to a lot of immune disorders. These immune disorders are less in developing countries," says Dr Randeep Guleria of the Department of Medicine, All India Institute of Medical Sciences (AIIMS).