We are installing a greenhouse (8×8 ft.) soon and there is some disagreement as to whether it is o.k. to smoke cigars inside. Is there definitive research on the effects of tobacco smoke and incidence of tobacco mosaic virus or other ill effects, other than the health ones, that is?
The effects of tobacco smoke on growing plants is the stuff of many science fair projects (like this example), most of which determine that the smoke stunts plant growth.
As for tobacco mosaic virus,University of Connecticut Integrated Pest Management has information on how to prevent this disease:
TMV is spread readily by touch. The virus can survive on clothing in bits of plant debris for about two years, and can easily enter a new plant from a brief contact with a worker’s contaminated hands or clothing. Tobacco products can carry the virus, and it can survive on the hands for hours after touching the tobacco product. Ensure that workers do not carry or use tobacco products near the plants, and wash well (with soap to kill the virus) after using tobacco products. Ensure that workers wear clothing not contaminated with tomato, tobacco or other host-plant material. Exclude non-essential people from greenhouses and growing areas.
University of California, Davis and Washington State University Extension concur with this information.
For general information on the toxins and irritants and added hazards of cigars in particular, see this information from the National Cancer Institute. It takes longer to smoke a cigar than a cigarette, so the duration of plant (and human) exposure to pollution is potentially longer as well.
Unless there is a compelling reason to smoke cigars in the greenhouse, I would avoid it, as it is not beneficial to the plants (or the smoker, of course) and more than likely will be detrimental.