Three ways climate change might affect your health

A new NZ report helps show why climate change is the world's major looming health risk, reports Eloise Gibson

A report just out from a Government-owned science company details the health risks to New Zealanders from climate change, helping to illustrate why it has been called the biggest contemporary health issue.

The Institute of Environmental Science and Research (ESR) report is dated September but was released only yesterday by Associate Health Minister Julie Anne Genter. It gathers peer-reviewed research to sum up the likely impacts on respiratory illness, skin cancer, infectious disease and other things.

While many risks were not within the report’s ambit - nutritional impacts, stress and communicable diseases among them - there is plenty to mull over. Genter has asked ESR to write a follow-up, advising how the health sector can adapt to the risks.

Here are three of the major issues identified:

1. Mould, pollen and smog

New Zealand already has one of the world’s highest rates of hay fever, and a staggering one in seven children are on asthma medication at any one time, according to the Ministry of Health.

While warmer winters may help reduce respiratory disease by decreasing air pollution from fires, there are other ways in which people will breathe less easy as the world warms.

First, pollen. Warmer average temperatures will help boost plant growth and may start the pollen season earlier - likely causing problems for hay fever sufferers. Meanwhile, warm humidity indoors may increase respiratory problems caused by mould, unless New Zealand gets on top of its problems with damp housing.

The report makes clear that researchers don’t yet know the magnitude of any increase in problems such as hay fever and asthma. The actual health effects will depend on localised changes, for example, changes in wind (carrying pollen), that aren’t yet fully understood.

Cities like Auckland may experience worsening summer air pollution from vehicle emissions, with more hot days increasing the effects of ground-level pollution (a major cause of death from respiratory and heart issues).

The Government and others could help people breathe easier by tackling fossil fuel pollution from cars and heating, ESR says.

2. Skin cancer and Vitamin D

New Zealand’s already high mortality and cost (an estimated NZ$123 million a year) from skin cancer could increase with people heading outdoors on hotter, dryer days – although there could be some benefits from increased Vitamin D exposure.

The potential rise in the sunburn risk comes from increased hotter, dryer days, leading people to want to spend more time outside.

Although projections are we’ll have more extreme rainfall in most places, and more rain full-stop in certain seasons and places, these wet times will be accompanied by a rise in dry, hot days over 25C - in other words, more extremes.

New Zealand is projected to have between 40 and 100 percent more hot days by 2040, depending on how much greenhouse gas we emit globally, and more dry days nationally, too. In some places, there will be less cloud - on the West Coast, for example, NIWA projects 10 percent more solar radiation in summer because of clearer skies. (Ironically, the West Coast is also in line for the largest increase in average rainfall).

At the same time, heat-trapping gases in the atmosphere will slow the recovery of the ozone layer from damage caused by ozone-depleting gases, allowing more UV light to get through to burn people.

As with the effect on breathing problems, the effects on our skin aren’t universally bad - if people head outdoors, for example, we might have fewer problems with low Vitamin D caused by sunshine deficiency. On the flipside, climate-induced migration might bring higher proportions of people with naturally darker skin to live here, says ESR, and they may suffer from low Vitamin D here.

People rely on sun to get most of their Vitamin D, which is important for bone health and immune function. 

“Potentially, the largest effect of climate change on Vitamin D levels will be through increasing migration to NZ from people with darker skin eg, due to sea level rise, increased temperature or weather events. People with darker skin are more prone to Vitamin D deficiency in New Zealand,” says the report.

ESR notes that both low Vitamin D and too much UV damage can be managed by calibrating our outdoor time and sun exposure during the year, and possibly by taking Vitamin D supplements. Quite how our habits will need to change to keep us healthy isn’t clear yet.

3. Infectious disease

“There is evidence that climate warming is causing profound and complex changes in the prevalence of some infectious diseases, through changes to pathogen’s life cycles, transmission and distribution,” says ESR.

Waterborne infections are expected to rise, partly because droughts can concentrate pathogens like cryptosporidium and giardia in the surface of water. Meanwhile, floods can flush pathogens into water and overwhelm drinking water treatment systems.

“Health officials are also observing the incidence of diseases like salmonellosis and cryptosporidiosis, as health experts believe that we will see higher rates of these diseases as conditions get warmer,” says the report.

Then there are diseases carried by the likes of mosquitos, sandflies, fleas and ticks.

New Zealand already has 15 species of mosquitoes (12 of them native) and, right now, they don’t seem to cause major disease problems. Nor does New Zealand have the problems with ticks (spreaders of Lyme disease) being experienced in the United States.

We do have cases of dengue fever (191 cases in 2016, a bad year), zika (167 cases in 2016) and malaria, although they’re often reported by people who’ve travelled overseas, says ESR. Dengue, Ross River and zika viruses and their mosquito vectors are not established in New Zealand.

However, if temperatures rise towards the higher/extreme end of scientists’ projections, some parts of New Zealand may become hospitable to exotic disease-carrying insects within 25-75 years, the report notes. Especially at risk are the northern parts of the North Island, where temperatures will rise the most. “If vector-borne diseases were to establish in New Zealand, a high percentage of New Zealand residents would be vulnerable due to not having protective antibodies,” says the report.

Experts are keeping a close eye on Australia, since most of the mosquitoes intercepted at New Zealand borders come from across the ditch.

In February 2017, three outbreaks of dengue fever were declared in Australia, though it’s not expected that New Zealand could become infested with it in the near future.

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