He works extensively on understanding mechanisms affecting lung function and pathology in various chronic respiratory diseases by external factors, such as environmental smoke and air pollution. Irfan primarily focuses on research regarding oxidative stress, inflammation, molecular clock, mitochondrial dysfunction, epigenetics, and cellular senescence by environmental tobacco smoke/tobacco products (cigarette smoke, e-cigarettes, flavoring chemicals in e-cigarettes, waterpipe/hookah, iQOS, CBD/THC, and cigars), airborne particulate matter, ozone, carbon nanotubes, nanoparticles, microplastics, and PFOS/PFAS Perfluorooctane sulfonic acid/perfluorinated alkylated substances, also called perfluorochemicals (PFCs) in the lung (Chronic Obstructive Pulmonary Disease and Idiopathic Pulmonary Fibrosis/Interstitial Lung Diseases), as well as oral/periodontal diseases. His major research emphasis and focus have been on understanding the pathophysiology of chronic inflammatory lung diseases particularly Chronic Obstructive Pulmonary Disease (COPD)/emphysema, lung cancer, and pulmonary fibrosis.