It is a daunting task. Contamination from the world's worst nuclear disaster since Chernobyl has spread far and wide, across fields and farms, rivers and forests. Tens of thousands of residents have been forced to flee their homes.

But, shovelful by shovelful, one half-empty city on the edge of the evacuation zone in Japan is fighting to bring its future back.

Feeling forgotten and left largely to fend for themselves by the central government, officials in Minami-Soma, about 12 miles (20 kilometres) away from the tsunami-crippled Fukushima Daiichi nuclear facility, have designated August as “Decontamination Month” in a campaign to woo spooked residents home.

Before the disaster, nearly 70,000 people lived in Minami-Soma. But, nearly six months later and despite relatively low radiation readings in most parts of town, more than 30,000 have left, nearly one-third of them from areas outside the official evacuation zone.

City officials fear that unless action is taken to demonstrate most of the town is safe for habitation, many may never return.

So, for the past week, the city has contracted local crews to hose down its schools, parks and community centres. The goal is to reduce by more than one-half the levels of radioactivity measured at places in the city where people gather.

The campaign has created a buzz of activity in the still-shaken town.

The work crews, clad in hazmat suits, also use bulldozers and power shovels to remove contaminated topsoil from public places, particularly school playgrounds. The wash off from the hosings and the mounds of contaminated topsoil are then moved to less-used areas and buried in huge trenches. For the time being, a large swath of Minami-Soma remains completely off limits.

That is because it is within a 12-mile (20-km) no-go zone set up by Tokyo days after the March 11 tsunami touched off meltdowns, explosions and fires at the Fukushima plant. All told, nearly 21,000 people were killed or remain missing after the tsunami, which devastated Japan's north-east coast.

But outside the no-go zone, contamination levels vary dramatically, depending on the local terrain. Still, most have stayed away because they fear for their health.

Some experts have reservations about the decontamination campaign. Hiroaki Koide, a radiation specialist and associate professor at Kyoto University's Research Reactor Institute, said simply removing the top three inches (5 cm) of soil has been shown to reduce radiation levels by about 90 per cent.

But he noted that the trees, roads and farmland near the decontaminated schools cannot be easily cleansed, and radiation from them can spread in the larger environment. Further, babies, children and pregnant women are the most vulnerable to radiation-related illnesses, and are generally advised to avoid exposure whenever possible.

“Any exposure would pose a health risk, no matter how small,” Koide said. “There is no dose that we should call safe.”

Another problem that has slowed the central government from acting to help is what to do with the irradiated soil, wash off and debris in the long-term.