There are 4,000 reasons why secondhand tobacco smoke is harmful - deadly in fact.

That is the shocking number of chemicals found in cigarette smoke - a complex cocktail of chemicals including more than 40 that are carcinogenic.

The three main components of cigarette smoke are:

  • Nicotine - a fast-acting drug that makes smokers crave cigarettes
  • Carbon monoxide - a poisonous gas that reduces oxygen in the blood stream causing breathing problems
  • Tar - a sticky black residue made up of thousands of chemicals that stays in the smoker's lungs and causes cancer.

Other harmful chemicals found in cigarettes include:

  • Formaldehyde - used to preserve dead bodies
  • Acetone - used in nail varnish remover
  • Ammonia - used in dry cleaning fluids
  • Arsenic - used in pest control and insecticides
  • Benzene - used in chemical manufacture
  • Cadmium - used in batteries

Breathing in secondhand smoke increases a non-smoker's chance of getting heart disease and lung cancer by a quarter and stroke by three-quarters

Secondhand smoke also exacerbates respiratory conditions like asthma, especially in children.

On December 6th 2005 Heart of Mersey (HoM) launched a dramatic Mersey-wide campaign warning of the dangers of secondhand smoke in the workplace.

The campaign came on the same day as the Government's Health Bill began its Committee stage in the Commons, where the issue of equal protection for all workers was debated.

A huge mobile billboard and a team in gasmasks spread the message about deadly secondhand smoke. The initiative was supported by an interactive website where the amount of toxic chemicals you absorb in your workplace - or bar - can be calculated.

The campaign was based on the successful model in the Republic of Ireland, where public attitudes against treating bar workers as second-class citizens played a key part in helping to enforce a smoking ban in 2004; 94% compliance in the first year was attributed mainly to public support.

Want to find out how much you've been inhaling? Visit www.4000reasons.org.uk

HoM believes that completely smokefree workplaces are the only way to protect against the harm done by secondhand smoke.