"Heavy smoke" means that there is a lot of thick and dark air filled with the ashes and particles from something burning, such as a fire or a cigarette. Full definition
A special gene variant increases the risk of heavy smoking. (sciencedaily.com)
When arriving on the scene, firefighters were greeted with heavy smoke. (effectivecoverage.com)
Such factors include heavy smoking, alcohol consumption and chronic stress, for example when the mother feels neglected and abandoned by her partner and family. (sciencedaily.com)