Despite the disease's pervasiveness, no one knows how it is caused, says Phillippa Ellwood, senior project manager at ISAAC.
"It's the 64-million-dollar question. A lot of people get muddled between triggers and causes. We know what the triggers are, things like privet and cigarette smoke, but not the causes."
Swathes of inconclusive research has been undertaken on how to reduce the risk of actually acquiring the disease. Initially asthma was blamed on genetics.
However, studies amongst identical twins revealed that only half of identical twins with one asthmatic twin had an asthmatic co-twin. Asthma can run in families, but this could be due to entrenched family habits or the surrounding environment.
"When our genetic studies didn't come out strongly, we thought the causes could be environmental. A family tends to eat the same things; it tends to be in the same, damp house. Families follow the same pattern because of the environmental link," states Ellwood.
The influence of environmental conditions on asthma - where you live, diet, medication - has also been investigated with varying results. One study illustrated a link between frequent paracetamol use in babies less than one year old and asthma prevalence in school-age children.
Research also found that those living on farms had lower asthma rates coupled with fewer allergies. New Zealand's air quality is positively pristine compared to other countries such as China, so the 'poor air quality' theory is out too.
According to respiratory specialist and NZ Asthma Foundation medical director, Dr Bob Hancox, what is clear is that obese and overweight women have higher chances of developing asthma as adults and, if already an asthmatic, more likely to have severe symptoms. The effect is strong for women, says Dr Hancox, and probably true for men.
A Finnish study in 2011 reported that overweight women were also more likely to have adolescent children with asthma.
In 2009, research from the University of Nottingham emphasised a high vitamin intake kept asthma at bay.
Leanne Male, assistant director of research at Asthma UK, says that although the jury is still out, increasing vitamin intake by eating a balanced diet is a good precautionary step, especially if there is a family history of asthma or during pregnancy.
Diet does seem to play a key role, says Ellwood. "From our ISAAC research we found that the higher the intake of fresh fruit, green vegetables, fish, cereals, pulses and grains, the less asthma and allergies were apparent. Conversely, the less of those food groups they ate, the higher the asthma allergies".
Children on the so-called 'burger diet' (three or more burgers a week) displayed an increased asthma risk. Irresponsible parenting? Or could this diet be just another indicator of hardship?
Professor Innes Asher, pediatrician and global authority on asthma, says New Zealand faces a triple jeopardy which impacts on asthma rates: "Poverty, poor quality housing which is cold, damp and overcrowded and poor access to primary health care."
One in four children grow up in poverty, around 270,000 children; a frightening statistic for a country we consider to be 'developed'.
If you look closer, the figure reveals entrenched ethnic inequalities - one in six Pakeha children versus one in four Pacific, and one in three Maori children. Maori children are also more likely to have more severe asthma and are twice as likely to be hospitalised for asthma.
Adults have a higher rate of the disease, one in four compared to one in seven for non-Maori populations.
Asthma Foundation Maori health manager, Sharon Cavanagh, points out that social inequality underpins the inequalities of health. "If people are living in a state of poverty their homes may be overcrowded, they could lack adequate heating, or lack income to provide heating. Many live in areas where it is difficult to access a range of health services. Then there's the whole issue of insufficient nutrition."
There should be Maori-specific initiatives in place, says Cavanagh, and programmes like 'Whanau ora' are on the right track. "My personal view is that if we get it right for Maori, we will get it right for everyone."
One of the biggest issues for Maori is smoking, says Cavanagh. Smoking in adults could have links to adult-onset of asthma, whilst secondhand smoke is associated with a risk in childhood and adulthood asthma. Pre-natal exposure to cigarettes may also be a factor in causing the disease.
A recent press release from Action on Smoking and Health (ASH) showed that in 2011, 14 to 15-year-old Maori had the highest reduction in smoking rates.
"Young Maori are taking a leadership role by saying, 'we don't want to do this - this isn't our future," she reflects.
In his book 'The Strategy of Preventive Medicine', Professor Sir Geoffrey Rose wrote, "the primary determinants of disease are mainly economic and social, and therefore its remedies must also be economic and social. Medicine and politics cannot and should not be kept apart."
Recent research from the University of Otago emphasizes that increasing social inequalities are creating inequalities of health and increasing hospital admissions for infectious diseases, including respiratory infections. In 2011 the OECD report 'Divided we Rise' highlighted that chasm between the wealthy and the deprived is increasing in Aotearoa, and fast.
In 2010 The Children's Commissioner Report observed a link between poverty, insufficient housing conditions and poor health including respiratory infections, asthma and depression.
The 'Growing Up in New Zealand' study found that one fifth of homes are often or always damp. 30.6% of houses in lower socio-economic areas were more likely to be damp, and even in wealthier suburbs the number was high at 11.9%. Incredibly, 20% of families in deprived areas had no form of heating at all.
Dr Julian Crane, co-director of He Kainga Oranga (Housing and Health Research Programme) says that increasing the insulation of a house can help in the fight against asthma. A snugly insulated house means fewer days off school and doctors visits for asthma sufferers.
He Kainga Oranga research also showed that unflued gas heaters, which give off asthma-inducing nitrogen oxides, should be swapped for flued gas heaters (that vent air pollutants and water vapour outside the home), pellet burners or heat pumps.
In houses where unflued gas heaters were removed, the severity of asthma decreased and the heating of the house improved. Many houses have bedrooms well below the World Health Organisation recommended temperature of 18c.
These types of statistics paint a bleak picture for the future of New Zealand, where asthma will continue to thrive in conditions of poverty and inadequacy. Known as the 'cinderella' of diseases, asthma has never actually been a priority for the Ministry of Health and its lack of specific causes make it hard to be tackled head on.
It's perhaps this lack of priority, and therefore lack of funded research, that explains why we know so little about the disease. Until a breakthrough is made, asthma will continue to burden the country by well over $800 million each year.
Personal and financial costs such as hospital admissions and absenteeism costs could be avoided with better treatment in the community, says chief executive of the Asthma Foundation Angela Francis.
"This would require improved access to asthma education and health care to provide better long-term control of asthma and prompt treatment of deteriorating symptoms. We need to make this a priority."
