The air we breathe: The scary stuff that can make us sick, or even kill
In part two of our 'Air We Breathe' series, Michael Daly examines some of the scarier stuff that goes unseen.
Breathing is the most natural thing in the world, but at times it can make us sick, and sometimes the air we breathe can even be a killer.
From the misery of hay fever that can affect an estimated one-third of New Zealanders, to the insidious threat of carbon monoxide that can kill without warning, many of the things we take into our bodies as we breath can be bad for us.
THE DREADED HAY FEVER
New Zealand has just the right sort of conditions for producing hay fever.
"Our humid, temperate climate is perfect for house dust mites, and we have a lot of pollen-producing trees, grasses and weeds," Allergy NZ chief executive Mark Dixon says.
"Add windy weather patterns to that and life can be very unpleasant for a lot of people."
Hay fever, which is technically known as allergic rhinitis, is the most common symptom of allergies and causes a runny, stuffy, itchy nose and frequent sneezing. It can also affect eyes, sinuses, throat and ears.
The main source of allergens in this country are house dust mites, which affect people year round, along with wind-blown pollens, which have the biggest impact in spring and summer.
Allergy NZ estimates around 1.5 million Kiwis suffer from hay fever and says international predictions indicate half the population will be suffering by 2025, mainly because of climate change.
"A recent study has found elevated levels of carbon dioxide increase the amount of grass pollen produced per flower. This means airborne grass pollen concentrations are likely to increase significantly in the future as greenhouse gases rise," Dixon says.
Allergic rhinitis has also been found to be a common trigger for asthma in both children and adults, while patients with allergic rhinitis have more frequent and prolonged respiratory infections.
Common diseases that spread through the air include influenza, measles and chickenpox. A University of Otago, Wellington study in 2014 calculated an average of around 400 people died in this country each year from causes associated with influenza.
Modelling showed a big variation in the number of deaths each year, from 31 in 1991 to 898 in 2003, with the virulence of the dominant circulating strain of the disease a key factor in how many people died.
Researchers found 86 per cent of the deaths were of people aged 65 and over. Most of those who died were killed by other illnesses that were triggered by influenza infection. Those illnesses included bacterial pneumonia and heart attacks.
"We need to keep remembering the huge toll from seasonal influenza, which comes around each year," lead author Dr Tara Kessaram said.
Vaccination has reduced the number of measles cases but there have been outbreaks in recent years. The most recent epidemic was in 1997 when 300 people were hospitalised. The most recent deaths from the disease were during an epidemic in 1991, when seven people died and 600 were hospitalised.
THE DEADLY GAS
Carbon monoxide is one of the scariest things to breathe. It's odourless, tasteless, invisible, doesn't irritate the nose, moth or skin, and is invisible. It can also kill.
Sources of the gas include incompletely burned carbon-based fuel, such as wood, as well as gas heaters, barbecues and internal combustion engines.
The risks posed by carbon monoxide were illustrated by the tragic deaths of Ashburton woman Cindy George and her three children in 2015, when the gas came from a car left running in a garage attached to the house they were looking after.
In 2016, a Canterbury man and his three sons came perilously close to death. They were using a generator, and even though it was outside, wind blew the carbon monoxide into the house. Just as they were about to go to bed one of the boys started having a seizure and lost consciousness.
"They were about to go to bed. I told [the father], 'you were very close to going to saying goodnight to your kids for the last time'," a local firefighter said.
The problem with carbon monoxide is that it sticks to the hemoglobin molecules in the body's red blood cells. It does it better than oxygen, stopping oxygen from getting to the brain, heart, or other cells, which start to die.
RISKS OF OLD BUILDINGS
With asbestos, the problem is that it is made of small fibres, which can be inhaled and lodge in the lungs, causing diseases such as asbestosis, lung cancer and mesothelioma. It can be decades before symptoms start to show.
Asbestos-containing products can no longer be imported into this country but any building constructed before 2000 is likely to contain asbestos, according to WorkSafe.
Asbestos that is left undisturbed and is in good condition or sealed is considered relatively safe, the Asbestos Aware website, developed for Greater Christchurch, says.
"(B)ut if it is easily crumbled, broken down, or damaged, or if you intend to drill it, sand it or break it up, it can be harmful and needs specialist attention."
"If you, or any contractors you use, don't plan work carefully and take appropriate precautions, you may spread contamination. This can settle on carpets, drapes and soft furnishings and become airborne at a later date. Don't expose yourself and your family to this risk."