Unlike triggers which provoke the asthma attack, asthma causes are not exactly known. However, due to the fact that asthma is prevalent in the developed countries – 7% of the population of the United States suffer from asthma some theories are more probable than the others. Factors which might be the main causes are generally divided into environmental, genetic and combination of both.
Health experts have no answer why some people get asthma and the others do not. Researches have shown that genetic predispositions are greater in some people than in the others. It is believed that people who have a family history of asthma as well as of atopic diseases and allergies are more likely to get asthma.
Due to highest incidence of asthma in developed countries experts believe that asthma is caused by some environmental factors.
Risk of asthma is greatly increased in people living in urban environment, being exposed to air pollutants such as smog or tobacco smoke, to various chemicals and living in too “sterile” environment during the early childhood. So-called hygiene hypothesis claims that people who are not exposed to certain amount of pathogens during their early childhood are more likely to be affected by various allergies as well as by asthma because the immune system cannot tell the difference between harmful pathogens and harmless antigens. Other most common risk factors are antibiotic use in early childhood, frequent respiratory infections in early age, obesity and stress.