Addressing disease at the population level must be the focus of the health system and its practitioners in the new era, says GP Dr George Crisp.

The past 150 years has seen the most remarkable and continuous progress in improving human health outcomes, with a dramatic fall in infant and childhood mortality and near doubling of longevity (and “health span”).

The emergence of modern medical science and means to apply it through parallel advances in engineering and technology have been key to this.

But while our high-tech individualised medical interventions and treatments have become the focus of healthcare, the majority of gains have resulted from preventive measures and applied at the population level.

For example, the single biggest health advance has been attributed to the introduction of water chlorination to eradicate water-borne disease in growing industrialising cities. Other important developments include sanitation, food safety, tobacco control, air quality, occupational and motor vehicle safety, maternal and infant health and vaccinations.

We are now facing new and emerging challenges arising from continuing growth and consequential interference of ecological and environmental systems.

Globally, there are rising rates of non-communicable diseases, novel pathogens, consequences of increasing climatic extremes and air pollution. In the developing world, malnutrition and diarrhoea, mediated through food and water insecurity, have never resolved and now face a renewed threat via these new environmental pressures.

The effective way to deal with these problems is through looking upstream to their origins, then understanding and addressing the determinants of them.

Dr John Snow addressed the cholera outbreak in central London, not by developing more effective rehydration agents, but by removing the Broad St pump handle and interrupting the source of contaminated water.

Climate change, identified as the greatest challenge to our health this century more than a decade ago, affects our health both directly, as so tragically experienced in Australia this summer, and by adversely affecting underlying conditions that support and protect our health, which jeopardises the functioning of our modern health services.

In parallel and for similar reasons, we are also losing biodiversity at an escalating rate, undermining ecosystems which are essential for production of food, medicines and many other health supporting services.

Solving these problems requires preventive action at a population level, that is public health*, and we can all play a role in promoting a health future both inside and beyond our consulting rooms.

For more information, the Planetary Health Alliance is an international consortium of over 200 universities, non-governmental organisations, research institutes, and government entities committed to understanding and addressing global environmental change and its health impacts

*Public health is defined as “the art and science of preventing disease, prolonging life and promoting health through the organized efforts of society” (Acheson, 1988; WHO).