How to Live on Planet Earth

Bethany Torr

In a very over simplified, and arguably unhelpful manner, Google provides this definition of urbanisation: “the process of making an area more urban”.

Nevertheless, let’s put some numbers to this definition. One-hundred years ago only 20% of the world population lived in a city. Factor in one industrial revolution, the emergence into the technological era and a massive increase in GDP per capita (wealth of people) and the result today? Over half of the world’s population live within urban areas.

This number is not set to remain here, however. In 2017, the global population size is ~7.5 billion and this is expected to increase to 10 billion by 2050. It is also expected by this date that over 75% of the world population will live in urban areas. It is expected that we’ll see for the first time, the majority of people in developing countries living within urban areas.

Mumbai_Skyline1

Image Credit: Wikimedia Commons

Whilst increasing world population is a driver in urbanisation. The greater availability of resources, wider job opportunities and higher salary pull people into cities. You only need to look at the number of graduate opportunities in London to know that cities pull people in this way.

Geoffrey West*, a physicist at the University of Cambridge, and colleagues identified that doubling the size of a city increases wealth, income, the number of available workers and creative people etc. by 15%. Essentially this equates to a 15% saving on all city infrastructure. This makes urbanisation increasingly attractive, especially for lower economically developed countries (LEDs).

On the surface, all of this makes urbanisation look desirable for increasing prosperity of countries and people. There are, however, a wide range of issues for both people and the environment that come alongside increasing urbanisation.

Beside the 15% increase in availability of people and wages upon doubling city size, a similar increase is observed in the amount of domestic and sewage waste. The major issue is that correct management of waste comes with a large price tag and for developing countries this cost can be too high.

Improper waste management may lead to issues with poor sanitation and disease. For example, during the 19th century when London’s population was dramatically increasing, there was a severe outbreak of Cholera in the Soho district. This was due to improper disposal of waste and excrement entering the water systems. This case, labelled the Broad Street cholera outbreak, was a large influence in increased investment into public health and improved sanitation in the UK.

There are also implications for the environment from improper waste management. Domestic waste that is not recycled is either placed into landfill sites or incarcerated. During the decomposition process, methane is released. A greenhouse gas that strongly contributes to global warming.

Leachate fluids are also produced during decomposition of waste. A term that refers to any liquid containing environmentally harmful substances. These fluids are a particular issue if the landfill sites are not properly contained, allowing the fluids to pass into water streams. This may alter oxygen content and be damaging to water species, as well as being damaging to the environment through evaporation and the water cycle.

The major environmental impact of urbanisation is loss of green space and natural habitats. The impact this has on the increasing atmospheric carbon dioxide levels is two-fold. A bigger city requires more energy and thus increasing the production of greenhouse gases from non-renewable fuel source. Additionally, as vegetation is removed for buildings, there is less atmospheric carbon dioxide taken up by plants and converted to oxygen through the process of photosynthesis. The potential loss of species through removing natural habitats is, also, a major issue.

The University of Sheffield are researching green roof technology designed specifically to overcome these environmental impacts of urbanisation. Extensive green roofs are composed of drought and weather resistant, small-growing plants, that require very little support from building structure. Allowing vegetation to be added to pre-existing buildings more easily than intensive green roofs, that are similar to normal ground landscapes, composing of trees and shrubs. The green roof technology aims to replace ground habitats onto rooftops, avoiding loss of species and reducing carbon dioxide levels within cities. The technology, also, has economic value by providing insulating properties to buildings.

The increase in urbanisation is happening so quickly that, in many places, the number of slums have also been increasing due to lack of available housings. These slums are formally known as “informal settlements” and pose huge health risks because of the lack of proper infrastructure, sewage and water systems and inadequate food storage. The overcrowding and lack of legal health and safety services are also likely to lead to increased violence, drug usage and negatively impact mental health.

While many countries are increasingly facing the struggles of urbanisation and major cities across the world are attempting to overcome pollution and climate change. Many pre-existing urbanised countries, such as the UK (90% of the population live in cities or towns), are seeing a greater movement in counter-urbanisation. With statistics suggesting that more people are attempting to move out of cities to the edge of urban areas instead.

The predicted increases in urbanisation and the impacts are most likely to be seen in African countries, where the 3bn increase in global population between now and 2050 will be concentrated.
*More from Geoffrey West about the maths of cities and corporations here.

Smoking’s Cancer Risk Explained

Bethany Torr

For a long time, it has been known that smoking significantly increases the chances of developing cancer. Yet despite this knowledge, smoking-related cancers still account for around a fifth of all UK cancer cases, making smoking the biggest preventable cause of cancer.

Tumours form due to mutations within cell DNA that allow cells to divide uncontrollably. For a tumour to become cancerous through further mutations, cells must also gain the ability to metastasise (spread to other parts of the body) and develop other traits which are known as the ‘hallmarks of cancer’. There were originally six hallmarks of cancer cells, but in 2011 this number was updated to ten:

cancer

The ten hallmarks of cancer (Hallmarks of Cancer: The Next Generation – Hanahan & Weinberg, 2011, http://dx.doi.org/10.1016/j.cell.2011.02.013)

Not every individual cancer cell will have all the hallmarks of cancer. It is likely that within a tumour, sub-populations of cancer cells will exist with different mutations, and therefore different hallmarks. The presence of cells with different mutations within a tumour is the reason that treating cancer can be so difficult.

Mutations occur naturally at a very low rate when DNA is copied to form new cells that replace dead cells. Research has found that smoking one pack of cigarettes a day can cause an additional 150 mutations in lung cells every year. Therefore, smoking significantly increases the risk of cells becoming cancerous.

Smoking causes mutations to arise due to oncogenic (cancer-causing) chemicals found within cigarettes. It is believed that out of the 250 known harmful chemicals in cigarettes at least 69 of these cause DNA damage, and consequently cancer-causing mutations.

The chemicals from cigarettes are absorbed into the bloodstream and transported around the body. This is how smoking causes not only mouth and lung cancers, but 12 other known cancers: including pancreatic, stomach, ovarian and liver cancers.

Strong evidence that smoking is the direct cause of tumours in multiple areas of the body came from collaborative research done at a number of centres, including the Wellcome Trust Sanger Institute. The research identified a mutational signature (a pattern of mutations) unique to the tumour cells of smokers.

They did so by comparing the mutations in tumour cells of smokers to the mutations found in tumour cells of non-smokers. The researchers identified mutational signatures, not only in lung cancer cells, but also in the tumour cells of mouth, bladder, liver, larynx and pharynx cancers.

The cancer risk associated with smoking was first suggested during the 1940/50s, due to a global epidemic of lung cancer following a marked increase in smoking uptake during the late 19th and early 20th century. Despite this, in the 1960’s only a third of US doctors believed that there was sufficient evidence to confirm the link between smoking and lung cancer.

Since this, the link has become widely accepted and despite tobacco company’s best efforts to glamorise smoking, rates of smoking in the UK have seen a marked decrease in the last few decades. In 2014, 19% of the UK population smoked, with slightly higher rates in men than women. This was a dramatic decrease from nearly half of the population 40 years prior.

The average number of cigarettes consumed has also fallen from around 16 cigarettes to more like ten cigarettes per day. The UK lifestyle survey suggests that smoking prevalence is greatest in young adults between the ages of 20 and 24 years old, whereas previously rates were highest in people aged between 25 and 59 years of age.

The changes seen in smoking rates in the UK between 1974 and 2014 are likely due to several initiatives and rulings implemented to reduce smoking, including:

▪ The prohibition of tobacco advertising on TV and radio in the broadcasting acts of 1990 and 1996
▪ The total ban on advertising and tobacco company event sponsorship in the UK in 2003
▪ The global ban on event sponsorship in 2005.
▪ The 2007 ban of smoking in enclosed public place – the biggest change in the UK but one that very few EU countries have implemented.

Since 2014, campaigning by Cancer Research UK (CRUK) and Action on Smoking and Health (ASH) has seen the introduction of further legislation that attempts to prevent people taking up smoking by making it less appealing.

The changes include the ban on displaying cigarette sales, and the ban on branding tobacco products – meaning only plain, standardised cigarette packaging is allowed. The UK is the second country to introduce laws that allow only this packaging and the decision was based upon the successful impact the same law had had on reducing smoking rates in Australia.

CRUK states that people using stop smoking services have a greater success rate when attempting to quit smoking compared to those who try alone. The Smokefree service from the NHS provides free text, email and face-to-face support, as well as an initial Quit kit and an app to help people quit smoking.