MAVO Year 4 · Gas exchange and excretion · Section 14.5

Air quality and lung disease

Why clean air matters

Air may contain harmful gases and particles from sources such as smoking, exhaust emissions and combustion. These can damage health and worsen existing lung conditions. Asthma and COPD are two conditions that can make breathing more difficult, but they have different patterns and causes.

Asthma

Asthma involves inflammation and variable narrowing of the airways. Triggers may include allergens, smoke, exercise or cold air, depending on the person. During symptoms, airway muscle can contract, the lining may swell and mucus can increase. This can cause wheezing, coughing, chest tightness or breathlessness.

Asthma is often long-term, but symptoms vary and may be absent for periods. Appropriate treatment can reduce inflammation and help control symptoms; its course differs between people.

COPD

Chronic obstructive pulmonary disease is a long-term condition involving persistent airflow limitation. It commonly includes features of chronic bronchitis and emphysema.

In chronic bronchitis, long-lasting airway irritation and inflammation contribute to coughing and mucus production. In emphysema, damage to alveolar walls reduces elastic recoil and can reduce the effective gas-exchange surface. Smoking is a major cause, while other harmful exposures and inherited factors can also contribute.

Existing structural damage is not normally reversed, but avoiding harmful exposure and receiving treatment can improve symptoms and help limit further deterioration.