Fog machines don’t just make it hard to see, they might also make it hard to breathe, according to a new study that says exposure to special effects fog may lead to a number of different ailments including wheezing, tightness in the chest, runny nose and headaches.

Exposure to glycol- and mineral oil-based fogs commonly used on stage, film and TV sets and at concerts ‘may contribute to both acute and chronic respiratory health changes in entertainment industry personnel,’ says researcher Sunil Varughese.

‘We also found that those who worked closest to the fog machines also had decreased lung function,’ he adds.

The study looked at workers who had regular exposure to fogs. It is not clear, however, if the effects are in any way permanent. The study is the first of its kind to look at fog machines on film and TV sets, and its authors stress that further study is needed.

In the meantime, Varughese and his colleagues at the University of British Columbia and its School of Occupational and Environmental Hygiene are recommending that crews limit their exposure to the kinds of fog identified in the report.

‘The problem is, right now there haven’t been any real levels set for the use of fogs. No one, as far as we know, has set levels that we could say are safe levels,’ he says.

‘We recommend reducing exposures to the crew. Eliminate fogs where they’re not important to the production.’ Steam-based fogs, camera filters or adding fog in post would be safer, he says. Crews could also shoot fog scenes at the end of the day, giving the air time to clear when the set is closed.

Both types of fog seem to affect breathing, but glycol-based fogs also seemed to cause headaches, dizziness and drowsiness.

The two-year study looked at film, TV and other entertainment workers in B.C., acting on a request from a provincial safety organization, Safety and Health in Arts Production and Entertainment. The results appeared this month in the American Journal of Industrial Medicine and the Journal of Occupational and Environmental Hygiene.