Teenagers on their way to school in Huambo's São Antonio district walk within one metre of the edge of a minefield.
Chatting unconcerned, and dressed in the white coats which are school uniforms in Angola, they pass by the field where some 20 deminers from the Halo Trust scrape away at the earth.
"I am doing this job because our country is one of the most heavily mined countries in the world," said deminer Ricardo Azvedo.
The method is to start with a trench, and then work sideways so as to minimise the chance of detonating the mine. Metal detectors are useless here in the central Angolan highlands. The area has been a battlefield several times, leaving the ground full of metal debris which would leave a detector beeping constantly.
Mechanically excavating the minefield would also pose too much of a risk. The field contains bounding fragmentation mines, lethal devices that spring out of the ground before exploding, and which in this location could send fragments flying across the school premises.
An area like the school is a high priority for de-mining organisations like the Halo Trust
"When we are assessing a minefield and deciding whether to clear, we have to consider the risk of accidents if the area is not to be cleared. A minefield that is close to a town would be considered important," explained Christian Richmond, the Halo Trust's programme coordinator for Angola.
"Then we have to look at the total number of beneficiaries and their status. Who is going to benefit from the removal of mines? [Hopefully] the poorest people around who need to farm or to build. And we need to look at the use to which the land will be put after clearance, the socioeconomic impact."
The peace accord signed in April between the Angolan Armed Forces (FAA) and the UNITA rebels has opened up new opportunities for Halo.
"Before the end of the war, Halo was working in a very restricted area," Richmond said. "So when it ended, we were able to expand our operations and begin to survey and re-survey. We have realised there is a lot to be done and a need to expand our programme considerably to give and adequate response."
But the arrival of peace has at the same time made the deminers' task more urgent, as displaced people head home to long-abandoned areas.
"The survey work Halo has done in the last few months indicates that most of these mines are concentrated around the towns and villages most of these people will be going back to," said Richmond.
Halo is looking at more than doubling the size of its staff in Angola, which at present stands at 350 local employees and only a handful of expatriates. The Trust has put in proposals to donors to help meet the extra demand, and has already received a donation of around US $1 million from the US State Department.
One continuing problem is the lack of information about where Angola's minefields are located. Mines have been laid by various military forces, both Angolan and foreign, and records have disappeared or never existed at all. But the end of the war has prompted engineers both from the FAA and UNITA to start divulging what information they have.
"While there is a lot of information missing, there is also some very good information that is being freely given to us," Richmond said.
He dismissed as "ridiculous" the unsubstantiated claims that there are millions of landmines buried in Angola. "The fact is that nobody knows how many mines there are in the ground in Angola - it's far wiser to look at the number of mined areas and that comes as a result of good surveying."
He added that in the central highland region where Halo works, there are about 500 mined areas, of which 127 have been cleared in the eight years that the trust has been operating there.
"So we are about a third of the way through the job. The point is it's not hopeless, there are not so many mines here that it will never be cleared - the fact is the job can be done," Richmond said.