Stainless steel sinks may up your risk of legionnaires’ disease

First published on 28.08.17 in the New Scientist.

A combination of rusty water and stainless steel taps, or faucets, can put people at risk of life-threatening legionnaires’ disease.

It’s already known that rust particles in a water system, which can come from iron pipes, encourage the growth of Legionella bacteria. These bacteria cause legionnaires’ disease, which can involve headaches, muscle pain, fever and confusion. The condition has been on the rise in Europe: in 2015, there were 7000 known cases, and the European Centre for Disease Prevention and Control (ECDC) thinks there may be many more that went unreported.

Now it seems that the protective coating on stainless steel fixtures – currently a firm favourite for kitchen and bathroom sinks – can degrade over time, encouraging the growth of Legionella species.

To better understand how the material of sinks can influence legionnaires’, Wilco van der Lugt, a safety engineer who contributed to European guidelines on preventing Legionella, and his team experimented with three kinds of tap commonly found in household water systems.

The researchers tested stainless steel, brass ceramic, and brass thermostatic mixer taps, each with clean water and water contaminated with either Legionella anisa, which is the most common strain in rust in the Netherlands, or both rust and the microbe. The team monitored this set-up for more than three years.

When rust was combined with Legionella anisa in the stainless steel tap, half the water samples ended up infected. The Legionella was much better able to survive and replicate in this combination than in the set-up that involved no rust, reaching concentrations of between 20,000 and 100,000 live bacteria cells per litre.

Safer taps

This outcome could be because the film coating of stainless steel taps degrades over time if rust particles are present in the water. By the third year of testing, the concentration of bacteria in this tap had shot up.

In contrast, the brass mixer tap seemed to be the safest, with only a quarter of samples from that experiment showing contamination, even when rust was present. Van der Lugt and his team thinks that taps for sale should be explicitly tested to assess their bacteria risk.

But Victor Yu at the University of Pittsburgh, Pennsylvania, says it isn’t possible to draw conclusions about safer tap design from the work, because this hasn’t yet been linked to people actually contracting legionnaires’ disease. He also notes that a different strain of Legionella is responsible for most cases in humans.

To avoid contracting legionnaires’ disease, the ECDC recommends keeping hot-water systems heated to between 50 and 60°C, and running taps regularly to avoid water standing for too long.

Journal reference: International Journal of Hygiene and Environmental Health, DOI: 0.1016/j.ijheh.2017.08.005

Mud bricks best for cool, green houses, says study

This article was first published on SciDev.Net, 28.06.17

Simple mud concrete bricks provide the most affordable and sustainable houses in the tropics, a Sri-Lankan study suggests.

Comparisons of four different types of walling materials revealed that mud concrete bricks have the lowest environmental impact and keep houses cool. They are also the cheapest, and easiest to dispose of once a house is knocked down.

Researchers compared mud concrete bricks with red bricks (modern fired clay bricks), hollow cement blocks and Cabook, the Sri Lankan name for bricks made from laterite soil, which are common in the tropics. The goal of the study was to find out which types of walling material are the most suitable for constructing affordable houses in the tropics, where population density and poverty are generally high.

“The sustainability of buildings and housing construction is essential to save lives and prevent inadequate living conditions.”

Christophe Lalande

“Why spend more money and destroy the environment more?” asks Rangika Halwatura, a civil engineer at the University of Moratuwa in Sri Lanka, and one of the authors of the paper.

Mud concrete bricks are made from soil in the same way as traditional mud bricks, but contain gravel and sand to improve their strength. The researchers looked at the carbon footprint of all four walling materials, and found that mud concrete bricks were the most environmentally friendly to produce and dispose of.

To check on thermal conductivity the researchers built one-square-metre model houses of the different walling types. Here, they found that red brick kept a house coolest, but mud concrete bricks performed almost as well.

Mud concrete bricks were also found to be the cheapest, at less than US$1,000 in Sri Lanka for an average-sized house, whereas red bricks cost nearly US$3,500.

Mud concrete bricks are widely used in other tropical countries but novel in Sri Lanka. They are popular because they are easy to make and therefore cheap, says Hurryson Moshi, a civil engineer in Tanzania. However, Moshi points out that as people grow wealthier they prefer the red bricks and cement blocks, as these are associated with higher socio-economic status.Walling material graph (FINAL)

Red Brick (modern fired brick), Cement (Hollow Cement Blocks), Cabook (laterite soil brick), Mud (mud concrete brick). Adapted from a graphic ©Udawattha and Halwatura, with permission. 

 

Moshi agrees with the study’s findings but says that other considerations, such as aesthetics, and symbols of modernity or social status, influence people’s choice of materials. Future studies should also take into account other sources of environmental damage such as deforestation (to produce timber to fire the bricks) or excavation of soil, he added.

In 2015, the government of Sri Lanka launched a programme to build 150,000 houses for the poor. This triggered the researchers’ idea to compare the different types of brick.

According to the United Nations, more than 850 million people around the world live in inadequate slum housing.

According to Christophe Lalande, leader of the UN-Habitat’s Housing Unit, poor neighbourhoods in developing countries are often the most affected by climate change and natural hazards such as storms and rising temperatures.

“The sustainability of buildings and housing construction, being adapted to the local environment, is essential to save lives or prevent inadequate living conditions,” he says.

Living near noisy roads could make it harder to get pregnant

This article first appeared in New Scientist, 26.06.2017

Living near noisy roads could make it harder to get pregnant

Living near a noisy road seems to affect couples who are trying get pregnant, increasing the likelihood that it will take them between six to 12 months.

That’s according to an analysis of 65,000 women living in Denmark. Jeppe Schultz Christensen of the Danish Cancer Society Research Center in Copenhagen and his team made this discovery by analysing data from the Danish National Birth Cohort, a project that ran from 1996 to 2002. They selected women who had tried to get pregnant during the project if traffic noise data was available for where they lived.

Previous research has suggested that 80 per cent of women who are actively trying to get pregnant usually do so within six menstrual cycles. But Christensen’s team found that for every 10 decibels of extra traffic noise around a woman’s home, there was a 5 to 8 per cent increased chance of it taking six months or longer.

This link persisted even when factors like poverty levels and nitrogen oxide pollution were taken into account. However, their statistical analysis showed that this association did not hold for women who took more than 12 months – perhaps because these couples may have had other factors affecting their fertility. “Road traffic noise may affect reproductive health,” says Christensen.

Him or her?

It is unclear whether traffic noise may be affecting women or their partners. Previous research has found a link between sleep disturbance and decreased fertility in women, as well as lower quality of semen in men. A 2013 study showed that consistent exposure to aircraft traffic noise activates a system in the brain that is known to disrupt the rhythm of ovulation.

Rachel Smith of Imperial College London says the link between traffic noise and health is worrying. Because traffic noise is common, even a small effect on health could feasibly have a large impact across a population, she says.

Europe’s roads are getting noisier. In the UK alone, an extra 2 million cars hit the road between 2011 and 2015. Christensen says traffic noise and fertility need to be investigated further before drawing up any recommendations for couples hoping to get pregnant, but Smith suggests that anyone who is worried could try to choose bedrooms away from the road, and close windows at night.

Marie Pedersen at the University of Copenhagen says traffic issues should be tackled by society as a whole, through better town planning and alternative transport. “It is a matter for urban planners and politicians,” she says.

Journal reference: Environment International, DOI: 10.1016/j.envint.2017.05.011

Read more: Dying for some quiet: The truth about noise pollution; Noise kills and blights lives in Europe

Bigger isn’t better for energy savings

This article first appeared on Climate News Network, 19.05.17.

LONDON, 19 May, 2017 Advances made in the energy efficiency of heating and transport are lost because of people’s desire to have bigger houses and cars, two research papers have shown.

Researchers have found that houses in England, Australia, Canada, the US and New Zealand are getting bigger as people want more space and extra rooms. This means there is more air to be heated, destroying any climate benefits gained by better heating systems and more efficient insulation, they say.

The study, published in ScienceDirect, found that most house buyers struggled to understand the actual amount of energy their new home would use. Instead, they took information on energy efficiency as a yardstick for consumption.

This means house-owners may think their new, efficient home uses little energy, when in fact it may use more than their neighbours older, smaller houses, says Helen Viggers, a researcher at the public health department of the University of Otago in Wellington, New Zealand, and a co-author of the paper.

Implicit trade-off

“There is general knowledge in the public that both house sizes and insulation standards have increased, and a feeling that both of these are probably ‘good things’,” she told the Climate News Network. “But there is less understanding of the implicit trade-off in energy requirements with increasing house size.”

Viggers is critical of measuring energy usage by square metre, as this “immediately hides [the fact] that larger houses use more energy than smaller ones”.

The New Zealand team also found that larger, stand-alone dwellings featured more wasted” space – such as large lobbies, corner space and little-used hallways. They were designed in a less energy-efficient way than multi-home buildings or small houses.

The findings of the study mirror a 2016 paper by a team of scientists from the University of Barcelona in Spain. They compared Spanish car-buying habits with advances in the energy efficiency of engines, and found that, instead of actually saving energy, people would buy bigger and faster cars.

With little awareness of actual energy consumption,
people involuntarily increase their carbon footprint
while thinking they are helping the environment

The Spanish researchers found that fuel efficiency would have improved by 32% and 40% for petrol and diesel cars respectively, if the cars had stayed the same size. However, they learned that car weight increased by 31% for petrol cars and 26% for diesel between 1988 and 2015, meaning modern cars actually use more fuel than those from three decades ago, despite being more energy efficient.

The New Zealand researchers admitted they did not know whether increases in efficiency directly led to larger-sized consumer objects, or whether other factors influenced people’s buying decisions. But such consumer behaviour has dire consequences for the environment, both teams warn in their papers.

With little awareness of actual energy consumption, people involuntarily increase their carbon footprint while thinking they are helping the environment, Viggers says.

Attractive alternatives

She and her colleagues say policymakers and homebuilders need to come up with better, more attractive smaller homes, and should design some “stunningly good” smaller dwellings.

“They should make the maximum use of the space available, have appropriate room sizes and be aesthetically pleasing,” says Viggers, “so that buyers can see an alternative that might work just as well as a larger dwelling for their family.”

She also supports the creation of mandatory energy certificates that take into account actual consumption, and not just heating efficiency, which would allow those moving into a new home to “make a more informed decision about what that dwelling is worth”.

“Thermal modelling earlier in the design process also forces the designer and builder to explicitly choose the level of energy efficiency they want, and therefore the trade-offs they have to make,” she says. Climate News Network

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