9 Asthma Risk Factors: What Puts People At Risk?

Bronchial asthma is a chronic inflammatory disease of the airways. It is a widespread disorder affecting people across the entire world — people of all ages and both genders. Still, there are some differences in prevalence among different groups of people, due to a variety of risk factors that contribute to the development and severity of the disease.

Genetics

Genetic studies on siblings and identical twins, but also on family members, have shown us the important role genetics play in the development of asthma. Although there is not a single gene we can blame for asthma, scientists have found that more than 100 genes and their variations (alleles), work in combination with environmental factors in such way that they facilitate the development of allergies and asthma. This type of genetic influence is called multifactor inheritance.

Gender

The development of asthma is related to gender, but the influence of gender is differs among age groups. For example, until puberty, asthma is more frequent in males than in females. During and after puberty, asthma symptoms in males are more likely to subside than in females. Furthermore, adult-onset asthma is more frequent in women than in men. This mechanism has not yet been explained, but scientists suspect that female sex hormones (primarily estrogen) play an important role in asthma development.

Allergy and atopic constitution

Reactions to inhalatory allergens are the most common causes of asthma development. There are people with so-called atopic constitutions, which means that they are prone to allergic reactions, usually to multiple allergens. These people are at a much higher risk of asthma than the general population. Allergic reactions cause the release of inflammatory mediators which can initiate the chronic inflammation of the airways. Although after that the pathological process is self-sustaining, the symptoms of asthma are always more severe when there is a higher concentration of allergen in the air.

Respiratory tract infections

Frequent viral and bacterial infections, especially during childhood, can damage the mucosa of the upper respiratory tract and make them susceptible to developing chronic inflammation. That is one of the assumed mechanisms, but it is a fact that many studies have found increased incidence of asthma in children with recurring infections of the respiratory tract.

Tobacco smoke

Tobacco smoke is one of the leading causes of morbidity and mortality in general. According to research, people who smoke are more likely to develop adult-onset asthma. Also, the length of smoking and the number of cigarettes per day correlate with the severity of asthma symptoms. Children whose mothers smoke while they are still pregnant often develop wheezing, which is one of the most common symptoms of asthma. The risk of asthma development in early childhood is even higher if women continue to smoke during the first year after childbirth.

Another harmful effect of smoking is second-hand smoke. Scientists have found that children who are exposed to second-hand smoke, usually by parents, are more likely to experience some type of respiratory disease, such as bronchitis, asthma, and frequent respiratory infections. Second-hand smoke is harmful to the airways of adults too. In one of the studies, an increased prevalence of adult-onset asthma has been noticed in flight attendants who were exposed to second-hand smoke during the time when smoking was allowed on airplanes.

Socio-economic status

In general, epidemiological studies show that children in families with lower socio-economic status have a higher risk of asthma development. However, different studies on this topic had different outcomes, so a clear conclusion regarding this risk factor cannot be made. Socio-economic status plays an important role in many medical conditions and further studies are needed to determine its exact role in asthma pathology.

Obesity

Obesity has recently been classified as a disease, and many studies have found that overweight and obese persons have an increased risk of inflammatory disorders, including asthma. The mechanism is still unknown, but people with existing asthma are always advised to keep their weight under control. Many patients with asthma reported that their symptoms improved after they took control over their body weight.

Air pollution

Other than allergens, there are substances in the air we breathe which are not causing an allergic reaction, but are highly irritative to our airways. Ozone (O₃), diesel exhaust particles, and nitrogen dioxide (NO₂) are some of the most common air pollutants, particularly present in cities and industrial areas. Chronic irritation of the respiratory mucosa may lead to the damaging of the local immunity, thus making a good environment for the development of chronic inflammation.

Occupational factors

In some workplaces there is an increased risk of asthma, because of the presence of harmful inhalatory agents. Painters, hospital staff, bakers, hairdressers, mineworkers, and many other professionals are facing this issue, because they are exposed to chemical vapors and/or dust particles, which can damage respiratory mucosa and cause asthma, emphysema, COPD, sarcoidosis, and other chronic lung disorders.