Smoking is bad for you, but you probably already knew that. The Center for Disease control reports that Cigarette smoking causes more than 480,000 deaths per year in the USA, 41,000 of those deaths from secondhand smoke. Smoking is also bad for your tomatoes and other solanaceous plants as well, no statistics are available on fatalities of tomato plants from second hand smoke but its probably at the very least equal to, and more than likely greater than the human fatalities.
The Nicotene in tobacco doesn't really harm the plants, in fact it is sometimes used as an insecticide, allthough not really all that advisable. Nicotine sulfate is toxic to nearly all mammals and requires extreme caution when handling and applying. It kills insects by disrupting their nervous systems. In Victorian England tobacco was steeped in water to manufacture it, it was then sprayed onto plants and sometimes livestock to ward off insects. Nicotine sulfate is not recommended , nor is it readily available, there are more suitable organic insecticides available.
What does harm the plants is a virus carried on the tobacco itself. If you are a smoker or use any type of tobacco, chew, smoke, snuff and stuff you really need to keep that crap away from your plants, your garden, your greenhouse. Tobacco, in any form, including the smoke can give tomatoes and related plants the dreaded disease Tobacco Mosaic Virus (TMV) as well as the related disease ToMV, or Tomato Mosaic Virus.
TMV is rapidly and readily transmitted from plant to plant. An infected plant brushes against a leaf of another plant - it's game on, same for gardeners who have recently smoked or used tobbacco in any form. Insects, even though they are non smokers [lol], can also spread the disease . Slightly less than half of all commercially available tobbacco products is infected with TMV, tobacco mosaic virus is not killed in curing.
Tobacco Mosaic causes leaves to be mottled light and dark green. The plants are generally stunted and the leaves rough. The tomatoes do not always show symptoms but may be reduced in size and ripen unevenly.
Fungicides are not effective in controlling Tobacco Mosaic, there are no known efficient chemical treatments that protect plants from this virus. Control of tobacco mosaic virus depends on reducing and eliminating sources of the virus.
If TMV is an issue, could be an issue or has been an issue in the past, for G-ds sake don't smoke by your plants. You may also want to consider planting resistant varieties. Take note that 'resistance' is not 'immunity.' Even disease-resistant varieties may encounter some growth and production difficulty when exposed to this virus.