The report, Reflecting on our Health, notes a decline in life expectancy, especially in deprived areas with people now living for more years of their life with ill health. It highlights that around 75% of deaths in people under the age of 75 in Wales are preventable but that successful prevention initiatives, such as tobacco control, have demonstrated the potential for significant improvements in population health over time.

If smoking rates had not changed in the past 10 years, there would be more than 170,000 additional smokers aged 18 or over. If smoker rates continue to reduce from the present 10% in Wales to 8%, it is estimated this change alone would prevent nearly 600 smoking-related deaths and 2,700 smoking-related hospital admissions each year.

The report calls for action across all levels of government and society to address the social, economic and environmental determinants of health; continue to support parents and early years education programmes for low-income families; encourage vaccination and screening take up; and help adults make healthier choices.

Key findings include:

• the average number of years that people in Wales can expect to live in good health is declining, particularly in women
• evidence shows public health programmes offer an average return on investment of 14 to 1.
• without accelerated action on prevention, people living with four or more long-term conditions could almost double by 2035
• preventable physical and mental ill-health is contributing to rising economic inactivity and increasing costs.

Professor Isabel Oliver, chief medical officer for Wales, said: ‘The evidence is clear – prevention is incredible value for money. Ahead of next week's Senedd vote on the Tobacco and Vapes Bill, there is no room for complacency - we need to see smoker rates continue to decrease. But we also need to replicate the progress in tobacco control across other areas – such as healthy eating and exercise.'

To strengthen prevention efforts, the chief medical officer has established a Preventing Ill-Health Advisory Group to provide national leadership and ensure prevention considerations are a key component of ministerial advice.

The Welsh Government is also introducing legislation that will make it mandatory for specified public bodies to consider the impact of their decisions - in sectors such as housing, education and transport - on long-term population health.