A 27-year-old man presents to A&E with acute dyspnoea and right-sided pleuritic chest pain after a bout of coughing. He is tall and thin, a smoker, and has no past medical history. Observations: RR 22/min, BP 120/76 mmHg, SpO2 97% on air. Chest examination suggests reduced air entry on the right. Chest X-ray shows a 2 cm rim of air between lung margin and chest wall at the level of the hilum with no mediastinal shift. What is the most appropriate management?