New EU-funded research shows that even very powerful ventilation systems cannot clear pub air of harmful substances from tobacco smoke. Tests have shown that one dangerous chemical remains at almost twice the level at which health effects are seen and 30 times the level in a non-smoking environment.
The research comes from the EU's top research centre at Ispra in Italy. The findings represent a further blow to vintners' hopes that some compromise might be reached on the proposed ban on smoking in the workplace, due to come into force in January.
The Joint Research Centre (JRC) at Ispra did follow-up research on whether strong ventilation was capable of clearing pub air of the dangerous substances including nitrogen oxides (NOX), benzene, toluene and carbon monoxide released by smoking. Earlier JRC research revealed by The Irish Times in September showed how ventilation could not eliminate these substances from an enclosed space.
Preliminary results from more comprehensive testing were given to The Irish Times by the director general of the JRC, Dr Barry McSweeney. "I know of no experiments in the US or anywhere else that have done this in this detail," he said, when contacted about the as-yet-unpublished research.
The study involved the automated burning of 20 cigarettes over a 37-minute period in an enclosed space. Ventilation levels were varied and measurements were taken of a range of substances given off by the cigarettes which would be taken up as passive smoking by those nearby.
NOX causes observable health effects at very low levels, Dr McSweeney said. "The lowest observed impact is only 200 parts per billion (ppb)." NOX is measured at just 10ppb in a clean air environment.
NOX levels reached 800ppb when ventilation reached one complete room air change in two hours and fell to 350ppb when the system completed five changes an hour. It showed however that ventilation could not clear the chemicals away, Dr McSweeney said.
"You are up to 30 times the clean air environment and above the level which in the literature shows you have problems," he added. "This is putting in context any question about ventilation. We have no axe to grind with anyone, we are only quoting facts."This research was only a tiny part of the JRC's activities and was not designed "to sabotage the vintners".
Modelling was used to simulate 10 air exchanges an hour, one full room air change every six minutes, but the NOX level still only reached 175ppb.
Similar measurements were done for carbon monoxide, but again the ventilation system, even when run at five full exchanges an hour, could not clear the air. The chemical levels tended to reach an equilibrium, Dr McSweeney said.
"You get it to equilibrium. The equilibrium level [for carbon monoxide\] is 15 parts per million (ppm). To the best of our estimates in a non-smoking environment it is 1.1ppm. We are getting this effect even at five exchanges per hour. I am making no health claims on carbon monoxide."
Benzene was also measured. Its levels did not fall in the test chamber even with two complete air changes an hour, he said.
"I am not claiming any health effects, but for modelled smoking in an enclosed space with ventilation, you cannot get back to clean air levels except by 20 exchanges per hour. I have absolutely no doubts on the figures."
The full report would be published in a matter of weeks, he added.
