Killer gas hard to find in pubs only days after smoking ban

Smokers are retreating to balconies. Picture / Brett Phibbs

The levels of a gas linked to cancer have plummeted in bars and on the breath of pub patrons since new smoking laws took effect.

Tobacco researcher Murray Laugesen said even he has been surprised by just how much the level of gases linked to second-hand smoking deaths had dropped.

The tests, understood to be the first of their kind in the world, were led by public health research company Health New Zealand and showed hydrogen cyanide gas levels in the six pubs and venues tested had fallen 40 per cent.

They had also fallen 45 per cent on the breath of five researchers who took part in the study since the smoking ban came into force on December 10.

Gas levels were taken before and after the law banning smoking in public places such as bars, restaurants and casinos.

The contentious law change - intended to reduce smoking-related deaths - has prompted claims it will cut profits for pub owners if smokers stay away, and in Wanganui on Saturday a woman bartender was allegedly assaulted after asking a patron to stub out his cigarette.

While some pub owners and employers say they will defy the law, others have introduced outdoor areas for smoking and report few problems or complaints.

Dr Laugesen, a long-time public health specialist and former chairman of anti-smoking lobby Action on Smoking and Health (Ash), has previously estimated that 400 people die each year from illnesses related to second-hand smoke.

He said yesterday that hydrogen cyanide had been identified as the leading gas in cigarette smoke to affect the heart and blood vessels, and nine out of 10 second-hand smoking deaths were linked to heart attacks or strokes.

He said the gas reductions suggested considerable health benefits for staff and patrons.

"That means there will be real [health] gains," he said.

The research was conducted by Health NZ, the University of Auckland's clinical trials unit and Otago University's national addiction centre, using a commercial model of a gas analyser made by Christchurch company Syft Technologies.

It is believed to be the first time researchers have been able to measure cigarette gas levels at such a sensitive level, and in real time.

The final stage of the research will be conducted today. Preliminary results have shown that in the public places tested the levels of some gases emitted by cigarettes have dropped a startling amount. The researchers asked five non-smokers - who lived with non-smokers - to provide samples of their breath before and after spending half an hour in each of six venues in Auckland and Christchurch, including pubs, casinos and clubs.

They also tested the air on the street and inside venues, taking more than 200 samples overall.

The third of four rounds of tests was taken five days after the smoking ban.

The levels of gases believed to be cancer-causing or linked to second-hand smoking deaths all reduced after the ban.

Gases did not disappear because they are present anyway, mainly through vehicle and industry emissions.

Greg Guthrie of Panmure said Sky City Casino had improved instantly after the ban.

"It's much better. In the past it was a case of just having to put up with it [smoke]. In some places it was always very thick."

A pokie machine player who did not want to be named said the air was much fresher.