Nearly 4,500 patients will lose their only NHS dentist in a Gwynedd town from the end of the month.
The My Dentist practice in Dolgellau will close on 31 March and the town's other practice is private.
A spokesman for the NHS practice said it had been unable to recruit a permanent dentist in the last two years
The deputy mayor of Dolgellau, Delwyn Evans, told BBC Radio Cymru's Post Cyntaf programme more needed to be done to get dentists into rural areas.
My Dentist clinical director Steve Williams said: "There is a shortage of dentists in parts of rural Wales where long-term unfilled vacancies persist over a significant period of time.
"We have tried unsuccessfully to recruit a dentist for the last two years and, regretfully, can no longer provide services at the Mervinian House Family Dental Practice."
What can patients at the practice do?
Find at an alternative dentist within Betsi Cadwaladr University Health Board by visiting its website.
- If you require urgent treatment when the practice has closed, or before they have registered with an alternative practice, contact NHS Direct Wales on 0845 46 47.
A spokesman for Betsi Cadwaladr Health Board said it intended to re-commission dental services in the area as soon as possible.
"However, there is likely to be a gap between the date of termination of the existing services and the completion of the tender exercise and the re-establishment of new services," he said.
"We are therefore making arrangements for the provision of dental services on a cover basis until a permanent solution can be put in place
"This will include exploring options for short-term support from the other nearest practices, as well as a dental out-of-hours clinic to operate from Dolgellau Community Hospital for patients requiring urgent unscheduled care."
A Welsh Government spokesman said: "When a dentist decides to reduce or end their NHS commitment, the associated funding remains with the health board to re-commission the service.
"Betsi Cadwaladr UHB has invited applications from dental contractors to help ensure there are NHS services available in the area.
"We expect the health board to continue to review and improve access to NHS primary care dental services through the targets set within its 2016-17 Operational Plan."
Is there a way to tackle air pollution?
The search for solutions to the threat of polluted air is generating ideas that range from the modest to the radical to the bizarre.
A London primary school may issue face-masks to its pupils. The council in Cornwall may take the extreme step of moving people out of houses beside the busiest roads.
Four major cities - Paris, Athens, Mexico City and Madrid - plan to ban all diesels by 2025.
Stuttgart, in Germany, has already decided to block all but the most modern diesels on polluted days.
In India's capital, Delhi, often choked with dangerous air, a jet engine may be deployed in an experimental and desperate attempt to create an updraft to disperse dirty air.
The World Health Organization calculates that as many as 92% of the world's population are exposed to dirty air - but that disguises the fact that many different forms of pollution are involved.
For the rural poor, it is fumes from cooking on wood or dung indoors.
For shanty-dwellers in booming mega-cities, it is a combination of traffic exhaust, soot and construction dust.
In developed countries, it can be a mix of exhaust gas from vehicles and ammonia carried on the wind from the spraying of industrial-scale farms.
In European cities, where people have been encouraged to buy fuel-efficient diesels to help reduce carbon emissions, the hazard is from the harmful gas nitrogen dioxide and tiny specks of pollution known as particulates.
The first step is to understand exactly where the air is polluted and precisely how individuals are affected - and the results can be extremely revealing.
Scientists at the University of Leicester are trialling a portable air monitor to gather precise data at a personal scale.
We watched as volunteer, Logan Eddy, 14, carried the device in a specially adapted backpack that recorded details of the air he was exposed to.
Exactly where he walked was then displayed as lines on an electronic map, the colour of those lines conveying how unhealthy the air was at different points.
It was much worse than WHO guidelines where he had waited to cross a busy junction, strikingly cleaner in a side-street but then almost off the scale in a sheltered spot beside an arcade of shops where a car was parked with its engine idling.
Seeing a graphic display of how pollution can vary so dramatically changed Logan's view of air, and his friends adjusted their behaviour immediately.
"The people who found out have stopped waiting right near the buses after school for their friends," he says.
"They've been waiting… further away from the buses.
"It's obviously had an impact on them."
The personal monitor is one of a range of devices being deployed in Leicester to build up a detailed picture of where pollution hotspots form - and when.
In many cases, they can be short-lived, appearing during rush-hours when traffic jams develop.
For Prof Roland Leigh, of Leicester University, understanding precisely where and when vehicles slow to a crawl or stop will help manage the flow of traffic in a way that minimises the impact on the most vulnerable people - the young and the elderly.
"One of the things we can all do is to improve our transport systems so that our congested traffic is not queued up outside of primary schools and old people's homes but instead is queued in other parts of the city where there's going to be less harm," he says.
But what about tackling one of the main sources of the problem in the first place, the vehicles spewing out the pollutants?
In Europe, under pressure from regulators, the manufacturers have progressively cleaned up their engines over the past few decades - first to trap carbon monoxide and unburned fuel, then particulates and most recently nitrogen dioxide.
The latest European standard, Euro 6, requires vehicles to emit far less pollution than older models, but trust has inevitably been eroded after the car giant VW was caught cheating - using software that activated the emissions controls only during tests.
At Bath University, engineers use a "rolling road" and a robotic "driver" to put cars through realistic simulations of how they are normally used, to find out exactly what's released from the exhaust pipe.
They are also working to understand the trade-offs involved in cleaning up an engine.
For example, adding more pollution-trapping devices can add to fuel consumption, which means increased emissions of carbon dioxide, undermining efforts to tackle climate change.
And however good the latest standards, they still leave vast numbers of older vehicles out on the roads.
Hence the idea of a national scrappage scheme - to provide incentives to drivers to switch to a cleaner model.
It's attracting growing support from an unlikely coalition including the Federation of Small Business, London First, Greenpeace and the Licensed Taxi Drivers' Association.
The challenge, as ever, is to find the money to make this happen and to agree who should pay - taxpayers through government incentives or the vehicle owners themselves.
Prof Chris Brace, an automotive engineer of Bath University, says; "Whichever way you approach it, you are asking people to spend more in taxation or more to buy new vehicles, and we need to decide whether that's something we're comfortable with as a society."
Some awkward choices lie ahead.
Will the parents of an asthmatic child dig deep in their pockets to switch to a cleaner car?
Will new housing developments include charging points for electric cars?
Will the money saved from a fuel-efficient diesel be seen as worth sacrificing for the sake of better air for everyone?
And bear in mind that these are "First World" questions.
In the rapidly growing cities of Africa, and many parts of Asia, there is hardly any monitoring of pollution at all, let alone political will or money to tackle it.
Why young people are now less likely to smoke
All age groups in the UK are smoking less - but the largest decrease is among 18- to 24-year-olds, according to the Office of National Statistics. Why is that?
The latest figures, for 2015, suggest one in every five (20.7%) 18- to 24-year-olds is a smoker.
In 2010, this figure was one in every four (25.8%).
Today, about 70% of 16- to 24-year-olds have never started smoking cigarettes in the first place, the data suggests - up from 46% in 1974, when records began.
And even among the age group most likely to smoke, 24- to 35-year-olds, about 60% - up from 35% in 1974 - have never picked up the habit.
Action on Smoking and Health (Ash) says: "We know that young people who try smoking are highly likely to grow up to become smokers, so the high numbers of young people reporting that they have never even tried smoking is good news."
Model Kylie Jenner was called a bad role model after she was pictured smoking on Instagram, perhaps an indicator it is no longer seen as cool.
The new data suggests 23.3% of 16- to 24-year-olds quit smoking in 2015, compared with 21.4% in 2010 and 13.4% in 1974.
Ash says this has been "achieved through a combination of effective legislation, policy and support for adults to quit over many decades - much of which has had a big impact on youth uptake as well as quitting".
Policy director Hazel Cheeseman says: "Creating an environment in which fewer young people try smoking and more smokers quit will protect the health of future generations and avoid hundreds and thousands of premature deaths.
"However, the achievements made to date are at risk.
"The government must urgently publish a new tobacco control plan for England and ensure this is properly funded."
In 2015, three out of every 100 16- to 24-year-olds used electronic cigarettes, up from one in every 100 in 2014, the new data suggests.
And, in total, 2.3 million people in the UK are using them - half in order to stop smoking.
But some are concerned vaping could prove a gateway to smoking for teenagers.
And critics say the fruit flavours of some e-cigarettes could make them more appealing to children.
In December 2016, the US Surgeon General said the use of e-cigarettes by children was "a major public health concern".
But Ash says the latest figures "confirm that most users are smokers or ex-smokers".
"The figures also highlight that most users are seeking to improve their health, with the most common reason for use being as an aid to quit smoking," it says.
"Where smokers make a complete switch, they can expect to significantly reduce their exposure to harmful chemicals which cause cancer and other smoking-related illnesses."