The ban of indoor smoking observed in clubs and pubs, is directing the problem of second-hand smoke from indoors to outdoors.

Monitoring of outdoor areas of several venues in NSW found smoke levels had increased by about four times since indoor smoking bans were brought into effect in July 2007.

According to a study conducted by the University of Western Study, indoor air quality had increased significantly, however, the problem of second-hand smoke was shifted from indoors to outdoors.

Dr Sue Reed, research leader said the study brought to light the issue of confining smokers in areas that are poorly ventilated, even though being outside.

She said, If you're a hospitality worker who has to go and serve people in those outdoor areas, or staff poker machines because we have outdoor pokies areas now, then you have moved it (the passive smoking hazard) from indoors to outdoors.

We set out to record the situation before the bans and after ... we did not expect the outdoor levels to increase, but they did.

Both before and after indoor smoking bans took effect, devices capable of detecting toxic ultra-fine particles in the air were installed at 10 venues and monitoring was conducted.

According to the World Health Organization's (WHO) recommended exposure for ultra-fine particles, said Dr Reed, went beyond the limit dozens of times outdoors sometimes reaching 20 times higher.

(In) the areas where people sat outdoors, the concentrations of ultra-fine particles increased and increased significantly above levels the WHO suggest could be problematic if exposed to for long periods, she said.

The smoke levels indoors decreased by 96 per cent following the introduction of smoking bans.

Dr Reed explained about the cloud a smoker brings inside when they return from having a cigarette which attributed to small amount of smoke found indoors.

At two of the venues, the spikes of very high indoor (fine particle) levels strongly correlated to large groups of smokers coming back inside at once.

Smoker's who've just finished a cigarette are still exhaling smoke and carry a cloud around them ... they do bring it back in with them.

While the level of smoke exposure indoors had improved for hospitality workers, they still had to spend a lot of time outdoors breathing in hazardously high levels of smoke.