New research from the ESRI shows the gap in life expectancy between manual and non-manual workers increased during the economic boom.

The gap is attributed to deaths from external causes - such as accidents, assaults and suicide - as well as digestive diseases and, in the case of women, cancers.

The mortality rate for men working in the manual sector from external causes was 2.3 times higher than professionals in the 1980s, but in the 2000s they were 3.9 times higher.

Evidence from previous studies suggests that suicide among younger unemployed men and increasing death rates in agricultural and industrial sectors may contribute to this.

The mortality rate for women in the manual sector from digestive causes was 1.5 times higher than professionals in the 1980s but had increased to 2.1 by the 2000s.

The report states that increases in deaths from digestive diseases such as cirrhosis are strongly linked to increased alcohol consumption.

The research has also found the death rate in the geographic area with the highest rate is four times that of the area with the lowest rate.

Overall, the research shows an average life expectancy increase of 15 years from 1950 to 2012.

It also shows that the rate of improvement in life expectancy has increased since 2000.

The reasons for the increase include reductions in smoking and improved cardiovascular and respiratory health.