The relationship between structure and function in asthma has been extensively studied. All the compartments of the airway have been shown to have some structural alterations contributing to functional defects. The structural alterations are thought to be a consequence of the chronic inflammation present in asthmatic airways, leading ultimately to remodeling. The decline of the ventilatory function over time in some asthmatic patients may be a consequence of airway remodeling. In this review, the authors describe the phenomena leading to airway remodeling and discuss the role of inflammatory mediators involved in this process. The structural alterations of the asthmatic airways are presented and the possible correlated functional defects are discussed.

Keywords: bronchii; pathology; asthma.

Over the past 250 years-since the Industrial Revolution accelerated the process of pollutant emission, which, until then, had been limited to the domestic use of fuels (mineral and vegetal) and intermittent volcanic emissions-air pollution has been present in various scenarios. Today, approximately 50% of the people in the world live in cities and urban areas and are exposed to progressively higher levels of air pollutants. This is a non-systematic review on the different types and sources of air pollutants, as well as on the respiratory effects attributed to exposure to such contaminants. Aggravation of the symptoms of disease, together with increases in the demand for emergency treatment, the number of hospitalizations, and the number of deaths, can be attributed to particulate and gaseous pollutants, emitted by various sources. Chronic exposure to air pollutants not only causes decompensation of pre-existing diseases but also increases the number of new cases of asthma, COPD, and lung cancer, even in rural areas. Air pollutants now rival tobacco smoke as the leading risk factor for these diseases. We hope that we can impress upon pulmonologists and clinicians the relevance of investigating exposure to air pollutants and of recognizing this as a risk factor that should be taken into account in the adoption of best practices for the control of the acute decompensation of respiratory diseases and for maintenance treatment between exacerbations.

Keywords: Respiratory System; Air pollution; Pregnancy; Pulmonary disease, chronic obstructive; Asthma; Respiratory tract Infections.