Transfer of particulate matter pollution from smoking to non-smoking coaches: the explanation for the smoking ban on Italian trains.

A major struggle is growing in Italy between the proand anti-tobacco lobbies concerning the voluntary decision of Trenitalia, the corporation that manages the long distance, reservation only Eurostar (ES) trains, which introduced a complete smoking ban starting from March 2004. However, even non-smokers are doubtful about a total ban and wonder whether this decision could be an excessive penalty for smokers on these trains, with journey times of up to six hours. Before the ban, ES trains had two smoking coaches (the first and the last carriages out of a total of 11). The smoking coaches were separated from the adjacent non-smoking carriages by automatic sliding doors and each coach was equipped with a separate HVAC (heat, ventilation, and air conditioning) system. To verify air quality in ES trains before the ban, we measured the concentrations of fine particulate matter (PM2.5) in the different coaches during a trip from Milan to Rome. PM2.5 comprises respirable particles , 2.5 mm in diameter, which represent a risk factor for respiratory and cardiovascular diseases and for lung cancer. 2 PM2.5 is also used as an official index of outdoor air quality (15 mg/ m as a maximum yearly average level of PM2.5 is the present US limit). It can be measured easily in real time (every two minutes) with portable instruments, and is a recognised although non-specific marker of environmental tobacco smoke (ETS). 4 As shown in fig 1, the first measures taken in a non-smoking coach positioned in the centre of the train detected PM2.5 concentrations mainly within outdoor limits (15 mg/ m), taken as reference for acceptable air quality, with the exception of a brief small peak around 7 pm. After transfer to the nonsmoking coach next to the smoking car, a dramatic increase of PM2.5 concentrations was found with a peak of 180 mg/m. As expected, measurements taken in the smoking coach revealed exceedingly high values of PM2.5 that reached a maximum of about 250 mg/m. Returning to the non-smoking coach far from the smoking ones, PM2.5 concentrations returned to normal values. Our data show that present HVAC equipments cannot preserve non-smoking coaches from ETS pollution deriving from smoking cars, which is transferred mainly to the adjacent cars, but can reach coaches further away, as shown by the isolated PM2.5 spike recorded at 7 pm. After these results were confirmed in supplementary monitoring in collaboration with Trenitalia, the company’s management took the decision to issue the smoking ban. Passengers of ES trains who choose to sit in non-smoking coaches have, for many years, been exposed to a hidden health risk, as these non-smoking coaches have, in fact, been heavily polluted by ETS from adjacent smoking cars. The acknowledgement of these data can be useful for the development of smoking policies on railways in other countries; moreover, if shared by the mass media, these findings could make a ban on smoking on trains more acceptable because such a measure is intended to preserve the health of non-smokers and rail employees, not to be merely prohibitive.