The substitution of fifty percent of combustible tobacco smoke exposure with either electronic cigarettes or heated tobacco products did not attenuate acute lung injury in an animal model.

•Substituting 50% of combustible tobacco nicotine exposure with ECIG or HTP does not reduce lung injury compared to 100% CS.•Even in a best-case scenario where smokers are able to partially substitute rather than augment cigarette use with ECIG or HTP products, we find no evidence of pulmonary disease risk reduction.