Toxic smoke

If you're sitting next to - or are in the vicinity of - a smoker you'll be breathing in their smoke. Even if a room's not particularly smokey, 85% of second-hand smoke is invisible and odourless, so you're still exposed to its toxic cocktail of over 4000 chemicals, including 43 cancer-causing carcinogenic agents. While some of the harmful substances are obvious - you only have to look at the ceiling and curtains of an old boozer to see the yellow stain of tar - it's the smoke wafting out of a burning cigarette that produces the most poisonous smoke. This contains a concentrated mix of chemicals such as hydrogen cyanide, ammonia and acrolein (formally used as a chemical weapon) - not something you'd choose to inhale.

Health risks

Passive smokers are exposed to the same health risks as smokers. In the short-term this can be:

• Irritated eyes
• Headache
• Dizziness
• Nausea
• Lung function is decreased in asthma sufferers
• Blood flow through the heart is reduced

The long-term effects include:

• Increased risk of heart disease
• Middle-ear disease
• Lung cancer
• Asthmatic attacks and reduced lung function in children
• Behavioural problems in children
• Premature birth and miscarriage
• Childhood respiratory disease
• Sudden infant death syndrome (SIDS)

How many people die?

Passive smoking kills 12,000 in the UK every year, but since the smoking ban was enforced in July 2007 the number of deaths has dropped significantly - especially in the workplace.

Those working in the hospitality industry were particularly at risk, but the new law means that virtually all enclosed public places and workplaces in the UK are smoke-free, creating a safer and cleaner environment. "The legislation resulted in a significant reduction in exposure to second-hand smoke," says Professor John Britton chair of the Royal College of Physicians Tobacco Advisory Group.

The main aim of the ban was to protect workers and the general public from the harmful effects of second-hand smoke, but it's also has a positive effect on people's attitudes towards smoking in general.

"Thanks to the overall improvement in the quality of the environment many smokers have also made their own homes smoke-free," says Professor Britton. There's also been a surge in people quitting altogether. Between April and December 2007 nearly 234,060 people quit smoking with the help of NHS Stop Smoking Services - that's an increase of over 20%.

Those still at risk from second-hand smoke

"Of course, there is still a risk of inhaling second-hand smoke, but it depends on your level of exposure," says says Professor Britton. "For example, if you're a security guard you're more likely to inhale second-hand smoke as a result of people congregating outside."

Children who live in a smoking household are also considered high risk. According to a recent report by the Royal College of Physicians (RCP), Passive Smoking and Children, the effects of passive smoking on the young costs the NHS £23.3 million a year. This includes treating at least 22,000 new cases of wheeze and asthma.

The future

Despite an overall positive response to the smoking ban, many young people still take up smoking. Tobacco kills around 87,000 people a year in England alone and it remains the single greatest cause of preventable illness.

The Government continues to push forward measures and policies to protect the public from second-hand smoke, but Professor Britton believes extending smoke-free areas is what's needed - especially places frequented by children.

"There's a loophole in legislation that needs to be addressed, and this includes smoking where there's a possibility of drift, for example outside windows, in doorways and playgrounds etc, and the effect this has on others."

Updated: 01/06/2011