Lifestyle and environment affect health and are shaped by socio-economic factors. The material circumstances of people’s lives and the behavioural choices they make are influenced by things like income, employment status and education.
Cancer has been the single biggest cause of death in New Zealand since the early 1990s. In 2015 it accounted for around 30% of all deaths. Most cancers are not strongly inheritable, and so are in theory preventable.
Lung cancer is mainly caused by tobacco smoking and exposure to second-hand smoke. It is one of the most common causes of death from cancer.
Tobacco consumption rose significantly in the 1930s and 1940s and stabilised from the 1950s to the 1980s, after which it dropped steadily. Male lung-cancer death rates peaked in 1965 but did not drop significantly until the 1980s. Female deaths peaked in the mid-1970s, but have not declined to the extent male rates have. Because women took up smoking later than men, female lung-cancer trends follow behind male trends.
Tobacco is the single biggest cause of preventable deaths in the world, as well as in New Zealand. In addition to lung cancer it is linked to bladder, liver, pancreatic, kidney, mouth, lip, throat and stomach cancer, leukaemia (blood cancer) and a growing list of other cancers. Tobacco contributes to heart and respiratory diseases and blindness, and is associated with infertility and foetal-development problems. Exposure to cigarette smoke is a major risk factor for cot death in babies.
There are socio-economic and ethnic inequalities in tobacco use and lung-cancer deaths. In the 2010s people living in the most deprived neighbourhoods were three times as likely to smoke as those living in the least deprived areas. Māori adults were 2.5 times as likely to smoke as non-Māori. Lung-cancer registrations and deaths increased with neighbourhood deprivation. Lung cancer caused 34% of Māori cancer deaths and 17% of non-Māori cancer deaths in 2015.
Other behavioural factors associated with cancer include excessive alcohol consumption, sun exposure, poor nutrition and obesity. 30–40% of work-related deaths through disease are due to cancer caused by exposure to toxic substances such as asbestos.
Cardiovascular diseases are also major causes of death. In 2015 coronary heart disease (mostly heart attacks) caused 16% of deaths and cerebrovascular disease (mostly strokes) caused 8%.
Coronary heart-disease rates peaked in the late 1960s and then declined steeply. The decrease was slower for Māori, who experienced higher rates of the disease than non-Māori in the early 21st century. Heart disease was overtaken by cancer as the single leading cause of death in the early 1990s.
The 7.1 magnitude earthquake which struck the Canterbury region on 4 September 2010 caused a big increase in recorded heart attacks. In the week after the quake, between eight and 10 people per day suffering heart attacks were admitted to Christchurch Hospital, compared to the usual two or three. Natural disasters cause a sudden and unusual surge of adrenaline in the body which can trigger a heart attack.
Though heart disease has an age and genetic component, major risk factors are associated with lifestyle – smoking, poor nutrition and low physical activity, which are in turn influenced by social factors. The decline in coronary heart disease is projected to slow in the 21st century, partly because of the emergence of an obesity (and type 2 diabetes) epidemic since the 1970s.
Unhealthy diet is a major cause of chronic disease in New Zealand. Researchers estimate an extra serving of fruit or vegetables per day would reduce deaths from coronary heart disease by 10%, and from strokes, oesophageal and stomach cancer by 6%.
Being overweight or obese causes ill health. The age-standardised obesity rate for the adult population increased from 19% in 1997 to 31% in 2014/15. New Zealand had a high obesity rate compared to other OECD countries.
Some New Zealanders have difficulty obtaining nutritious food for economic reasons. In a 2010 study, almost half of low-income households regularly ran out of food through lack of money.
Housing and pollution
Cold, damp houses and polluting indoor heating are associated with respiratory problems such as asthma. Studies in the 2000s found that insulating houses and installing non-polluting heating resulted in higher average temperatures, less mould and condensation, lower nitrogen-dioxide levels, improved respiratory health, fewer days off school and work, and fewer doctor visits.
A 2012 report found that air pollution (mainly caused by emissions from home heating, vehicles and industry) was associated with 1,175 premature deaths, 607 extra hospital admissions for respiratory and cardiac illness and 1.49 million restricted-activity days (when people cannot do activities they may have undertaken if pollution was not present) each year.