[eng] To inform the clinical practice guidelines' recommendations developed by theEuropean Academy of Allergy and Clinical Immunology systematic reviews (SR) as-sessed using GRADE on the impact of environmental tobacco smoke (ETS) and ac -tive smoking on the risk of new- onset asthma/recurrent wheezing (RW)/low lungfunction (LF), and on asthma- related outcomes. Only longitudinal studies were in -cluded, almost all on combustion cigarettes, only one assessing e- cigarettes andLF. According to the first SR (67 studies), prenatal ETS increases the risk of RW(moderate certainty evidence) and may increase the risk of new- onset asthma andof low LF (low certainty evidence). Postnatal ETS increases the risk of new- onset asthma and of RW (moderate certainty evidence) and may impact LF (low certaintyevidence). Combined in utero and postnatal ETS may increase the risk of new-onsetasthma (low certainty evidence) and increases the risk of RW (moderate certaintyevidence). According to the second SR (24 studies), ETS increases the risk of se -vere asthma exacerbations and impairs asthma control and LF (moderate certaintyevidence). According to the third SR (25 studies), active smoking increases the riskof severe asthma exacerbations and of suboptimal asthma control (moderate cer -tainty evidence) and may impact asthma- related quality- of-life and LF (low cer-tainty evidence).