This is an article from I’ve Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to firstname.lastname@example.org
In Japan, many people wear face masks – is that to prevent the wearer getting the infection, or is the wearer already infected and protecting those around? Is the mask useful in protecting against viruses or bacteria? – Petrina, Greenwich
Thanks for your question, Petrina. You’re right, in countries like Japan and China, facemask use in the community is widespread – much more so than in Western cultures. People wear them to protect the respiratory tract from pollution and infection, and to prevent the spread of any pathogens they might be carrying.
Whether this works depends on the type of mask.
There are three supposed ways a mask can provide protection: by providing a physical barrier (which prevents splashes and sprays), by filtering the particles (blocking particles of a certain size from entering the respiratory tract), and by fitting around the face to prevent leakage of air around the sides.
Some mask makers have also gone the extra step of using antimicrobials and claim to kill bugs on the surface of the mask, but these haven’t been tested to see if they provide any benefit.
Healthcare workers have been using cloth masks (made of cotton or other materials and with ties to secure them at the back) while caring for patients since the late 19th century to protect from various respiratory infections such as diphtheria, scarlet fever, measles, pandemic influenza, pneumonic plague and tuberculosis.
During the mid 20th century, disposable surgical facemasks (similar in look to the cloth masks but made of paper) were developed. Surgical masks were developed to prevent the surgeon from contaminating the wound during surgery, but studies have not proven they help.
These were followed by respirators, which vary in shape and material but are designed to fit around the face and filter particles. Respirators are designed specifically to protect the respiratory tract from inhaled germs. There are many types, which may be reusable or disposable.
People must undergo fit-testing to ensure respirators are correctly fitted, with a good seal around the face. Unlike masks, respirators are subject to certification and regulation, and are proven to protect against respiratory infection.
Surgical masks are unregulated for filtration and do not fit around the face, and the evidence for their use is less convincing. In a community study, families with a sick child who wore such a mask were less likely to get sick if they also wore a mask, but many family members didn’t wear their masks all the time.
In a university setting, students were protected from sick classmates if they wore the mask within 36 hours of their classmate getting sick.
In many low income countries, the cost of even paper surgical masks is prohibitive, so cloth masks are used, washed and re-used. But these don’t protect against infection, and may even increase the risk of infection.
Prevention of infection vs source control
Masks can be used to protect healthy people (such as nurses and doctors) from exposure to infection, but are also used by sick people (such as a TB patient) to prevent spread of infections to others (called “source control”). There is less research on this use than on the use of masks by well people. The efficacy of source control is unknown.
Do masks work?
It’s long been thought surgical masks protect from transmission of pathogens, which spread through the air on large, short-range droplets, while respirators protect against much smaller, airborne particles, which may remain suspended in the air for several hours and transmit infection over long distances. So most guidelines recommend a mask for droplet transmitting infections (such as influenza) and a respirator for airborne infections (such as TB and measles).
But we’ve shown respirators protect better than masks even against droplet-spread infections. And the longstanding belief that infections neatly fit into either droplet or airborne transmission is not correct. Respiratory transmission of infections is more complex than this.
To say whether masks work, we have to specify whether we’re talking about a respirator, a surgical mask or a cloth mask.
The respirators are the Rolls Royce option and do protect, and this is a tool for frontline health workers facing epidemics of known and unknown infections. Surgical masks probably also protect but to a lesser extent. But there’s no evidence cloth masks will protect against invading or escaping bugs.
As unlikely as it may seem, your drive to the supermarket is responsible for a lot of noise pollution in our oceans – and a lot of stress to marine life as a result.
Of course, it’s not the specific sound of your car trundling along the street that the fish and whales hear. But many of the products that feature in your weekly shop – from the goods you buy, to the petrol you burn, to your car’s component parts – contribute to marine noise pollution.
Let’s start with the oil. Before we can drill the oil or turn it into fuel to drive our cars, oil companies have to discover it.
Companies look for oil using high-pressure airguns. These machines are towed across the surface of the ocean, firing off sounds to determine the make-up of sediment layers in the seafloor. These are some of the loudest human-created sounds – researchers working in the middle of the Atlantic Ocean have been able to record the sounds produced from coastal oil surveys.
These sounds are problematic for marine life. Whales and other animals that rely heavily on sound for communicating and finding food are most affected. Hearing is to these animals much the same as vision is to humans. Unusually loud sounds can disturb whales’ behaviour and, if they are close enough, can damage their hearing. There is even some suggestion that the airguns can cause whale strandings, although this is not yet completely certain.
Currently, one-third of all oil comes from offshore sources and this proportion is expected to increase. This can only mean more bad news for our marine life.
What about the metal box that consumes all the oil? Parts for the car are sourced from all over the world and have to be shipped across our oceans. In turn, the raw materials needed to make these parts are usually shipped in from yet more places. The commercial shipping needed for all this represents another problematic source of ocean noise.
The contributions of individual ships may seem trivial in comparison to the loud noise from airguns. However, the world merchant fleet includes around 52,000 ships. Collectively, these increase the ambient noise levels in our oceans. In fact, the amount of low-frequency sound in some parts of our oceans has doubled each decade over the past 60 years.
Humans perceive only some of this sound, because of the very low pitches involved. But these sounds are well within the frequency range used by baleen whales. Recent work suggests that this constrains the communication ranges in whales, causing chronic stress and potentially interrupting mating behaviour.
Oh, and most of your groceries are shipped around the world at some point too, as are many other consumer items – including the battery in your hybrid car, if you have one. Around 90% of world trade is carried by commercial ships at some stage. Not all of this ends up in your shopping bag, but a large proportion enters the consumer market at some point.
Certain grocery items, such as fish, originate from the oceans themselves. Like cargo ships, fishing vessels produce noise from their engines and propellers, but they also have noisy fish-finding sonars and winches as well.
The good news is that noise pollution, unlike chemical pollution, dissipates quickly. This means that the future for underwater noise remains bright. If you want to give the whales a break, just drive a little less, or support higher efficiency standards for vehicles. This will not only reduce oil consumption, but also the wear and tear on your car, meaning that fewer replacement parts will need to be shipped in.
You can also buy locally produced items and support the local economy too. That way everyone wins.
No matter how connected we think everything is, the situation is generally even more complicated than we can imagine. So next time you walk to the shops and buy an apple grown in your state, you should allow yourself a moment to feel good about yourself, safe in the knowledge that you have helped to make the oceans a tiny bit quieter.
Nothing uses more resources or produces more waste than the buildings we live and work in. Our built environment is responsible for half of all global energy use and half of all greenhouse gas emissions. Buildings consume one-sixth of all freshwater, one-quarter of world wood harvests and four-tenths of all other raw materials. The construction and later demolition of buildings produces 40% of all waste.
The sustainability of our buildings is coming under scrutiny, and “green” rating tools are the key method for measuring this. Deakin University’s School of Architecture and Built Environment recently reviewed these certification schemes. Focus group discussions were held in Sydney and Melbourne with representatives in the field of sustainability – including government, green consultancies and rating tool providers.
Two main concerns emerged from our review:
Sustainability ratings tools are not audited. Most ratings tools are predictive, while those few that take measurements use paid third parties. Government plays no active part.
The sustainability parameters measured only loosely intersect with the building occupants’ sustainability concerns. Considerations such as access to transport and amenities are not included.
That’s the backdrop to the sustainability targets now being adopted across Australia. Australia has the highest rate of population growth of any developed country. The population now is 24.8 million. It is expected to reach between 30.9 and 42.5 million people by 2056.
More buildings will be needed for these people to live and work in. And we will have to find ways to ensure these buildings are more sustainable if the targets now being adopted are to be achieved.
So how do green ratings work?
Each green rating tool works by identifying a range of sustainability parameters – such as water and energy use, waste production, etc. The list of things to be measured runs into the dozens. Tools differ on the parameters measured, method of measurement, weightings given and the thresholds that determine a given sustainability rating.
There are over 600 such rating tools worldwide. Each competes in the marketplace by looking to reconcile the credibility of its ratings with the disinclination of developers to submit to an assessment that will rate them poorly. Rating tools found in Australia include Green Star, NABERS, NatHERS, Circles of Sustainability, EnviroDevelopment, Living Community Challenge and One Planet Communities.
So, it is easy enough to find landmark developments labelled with green accreditations. It is harder to quantify what these actually mean.
Ratings must be independently audited
Government practice, historically, has been to assure building quality through permits. Planning permits ensure a development conforms with city schemes. Building permits assess structural load-bearing capacity, health and fire safety.
All this is done off the plan. Site inspections take place to verify that the building is built to plan. But once a certificate of occupancy is issued, the government steps aside.
The sustainability agenda promoted by government has been grafted onto this regime. Energy efficiency was introduced into the residential building code in 2005, and then into the commercial building code in 2006. At first, this was limited to new buildings, but then broadened to include refurbishment of existing structures.
Again, sustainability credentials are assessed off the plan and certification issued once the building is up and running. Thereafter, government walks away.
We know of only one longitudinal energy performance study carried out on domestic residences in Australia. It is an as-yet-unpublished project conducted by a retiree from the CSIRO, working with Indigenous communities in Far North Queensland.
The findings corroborate a recent study by Gertrud Hatvani-Kovacs and colleagues from the University of South Australia. This study found that so-called “energy-inefficient” houses, following traditional design, managed under certain conditions to outperform 6- and 8-star buildings.
Sustainability tools must measure what matters
Energy usage is but the tip of the iceberg. Genuine sustainability is about delivering our children into a future in which they have all that we have today.
Home owners, on average, turn their property around every eight years. They are less concerned with energy efficiency than with real estate prices. And these prices depend on the appeal of the property, which involves access to transport, schools, parks and amenities, and freedom from crime.
Commercial property owners, too, are concerned about infrastructure, and they care about creating work environments that retain valued employees.
These are all core sustainability issues, yet do not come up in the rating systems we use.
If government is serious about creating sustainable cities, it needs to let go of its limited, narrow criteria and embrace these larger concerns of “liveability”. It must embody these broader criteria in the rating systems it uses to endorse developments. And it needs an auditing and enforcement regime in place to make it happen.