Sulfur dioxide, as one of the main air pollutants, is described as an important cause of cardiorespiratory disease and associated mortality. Exposure is primarily seen in the occupational setting. Known for its effects of inducing bronchoconstriction after inhalation, patients principally report symptoms such as dyspnea and cough, whereas rare cases may progress to severe insufficiency. The diagnosis rests on identifying exposure and clinical workup by the physician.
Sulfur dioxide (SO2) is one of the more important air pollutants described in the literature, along with nitrogen dioxide (NO2) and carbon monoxide (CO) . Having in mind the fact that SO2 arises from both natural and industrial (fossil fuel combustion, smelting) sources, poisoning from this gas can be seen in both occupational and non-occupational circumstances  . Several studies have confirmed its effect on human body, most notably on the respiratory system     . Namely, bronchoconstriction, as a result of an inflammatory reaction and irritation of the bronchial mucosa, is one of the principal effects of SO2, which may result in symptoms such as dyspnea, wheezing, and a cough, but also exacerbation of underlying pulmonary disorders, such as asthma   . In fact, reports indicate that SO2-polluted air might be one of the causes of increased prevalence of asthma in the pediatric population . Mucosal hypersecretion is also described as an important symptom of sulfur dioxide poisoning . Prolonged exposure to high concentrations of SO2 might lead to more severe forms of respiratory injury, including pulmonary fibrosis and acute respiratory distress syndrome (ARDS) . Cigarette smoking was identified as a risk factor for a more severe respiratory symptomatology . In addition to lung-related symptoms, many studies have established a strong connection between increased mortality rates due to cardiovascular diseases and exposure to SO2   . SO2 is known for its ability to disrupt neuronal signaling responsible for heart rate control and may result in tachycardia, although cessation of exposure to SO2 is sufficient to abolish its effects . Because SO2 is a mucosal irritant, its harmful effect on the conjunctiva, the gastrointestinal tract, and even the skin, is also described.
The diagnosis of sulfur dioxide poisoning might be challenging, especially in the absence of specific tests. For this reason, the physician and its ability to perform a detailed clinical assessment is the essential step in the workup. In the presence of undisclosed respiratory complaints, a complete patient history, including the patient's socioepidemiological data (living in industrial areas, or in proximity to factories or heavily polluted areas). The patient's occupancy (and to which substances is the individual exposed on a daily basis) must be assessed during history taking, as studies point to chronic low-dose SO2 exposure at the workplace as a very important source  . Physicians must also identify whether undrelying chronic pulmonary diseases are present and if exacerbation of associated symptoms has occurred. Once the clinical evaluation is completed, pulmonary function testing (in the form of spirometry) and imaging studies (either plain radiography or computed tomography) of the chest should be employed , primarily to determine the optimal therapeutic strategy.