Clean-up workers have begun a huge “decontamination” operation around Notre Dame Cathedral after a health scare over lead particles from the fire.

It is the second attempt to remove hazardous dust spread across a swath of central Paris that settled on homes, schools and on the ground after the blaze in April that destroyed the cathedral’s roof and spire.

Police sealed off the area around the cathedral to vehicles and pedestrians on Tuesday morning as the 10-day clean-up began. The nearby suburban train station has been closed and buses diverted.

Q&A Who has given money to rebuild Notre Dame? Show The race to restore Notre Dame cathedral has topped €1bn (£865m) in donations. Bernard Arnault: €200m

Billionaire businessman Arnault announced he would donate €200m through his LVMH luxury goods group just hours after his business rival Francois Pinault announced he would contribute. Francois-Henri Pinault: €100m

Pinault, husband to actor Salma Hayek, was the first to announce a major donation, of €100m through his company Artemis. L'Oréal: €200m

The cosmetics group, along with the the Bettencourt Meyers family who own the company and the Bettencourt Schueller foundation, will give €200m in total. Total: €100m

The French oil and gas major has committed €100m.

City of Paris: €50m

The city will give €50m to rebuilding efforts, according to mayor Anne Hidalgo. BNP: €20m

The banking group has said it will donate €20m. JCDecaux: €20 million

The French outdoor advertising group, known for its public bike rental systems and street furniture, will give €20m. Axa: €10m

The French insurer pledged €10m. Fimalac: €10 million

Marc Ladreit de Lacharriere, who runs the investment company, will give €10m. The Bouygues brothers: €10m

Martin Bouygues and his brother Olivier, who run one of France’s biggest construction companies, have said they will give €10m. Société Générale: €10m

The bank has pledged €10m. Île-de-France: €10m

The regional authority that includes the French capital has donated €10m. Walt Disney Company: $5m

The American entertainment group will donate $5 million, according to Robert Iger, the chairman and chief executive of Disney. Auvergne-Rhône-Alpes: €2m

The local government said it would give €2m. Capgemini: €1m

The IT services company has pledged €1m. International Olympic Committee: €0.5m

The IOC has said it will give half a million euros ahead of the 2024 Olympic games. Photograph: Lionel Bonaventure/AFP

Decontamination teams will use “ultra high pressure” water hoses filled with a chemical detergent or gel which will then be vacuumed up, taking the lead with it, officials hope.

Experts say 400 tons of lead from the roof and spire burned during the blaze that engulfed the cathedral, threatening the collapse of the entire edifice.

The regional prefect said work on consolidating the damaged building – halted over health concerns for site workers – would begin again next week.

“Our priority is to foresee any risk that could affect employees working on the site,” Michel Cadot, the prefect, said in a statement.

Several schools and creches in the area are being decontaminated before term starts in September and 162 local schoolchildren have been tested for lead levels – 16 were found to have levels that need monitoring and one child was found to have a worryingly high level, but officials said it was unclear if this was linked to Notre Dame or his home.

In May, police and officials said the air around Notre Dame was not toxic.

Last week, Annie Thébaud-Mony, research director at Inserm (National Institute for Health and Medical Research), said the lead contamination was worrying.

“We have to realise that the 400 tons of lead that were spread corresponds to four times the lead emissions in the whole of France for a year,” she said.

“Lead is as bad as asbestos in terms of poison. At the time of the blaze, the firefighters should have been better protected, in my opinion. The same goes for those who began work (on the cathedral).”

She added that the French authorities were sending contradictory messages: “On one side we have the talk of rebuilding the cathedral in five years; on the other, the minimising of the risk, to the point of denial, regarding the level of lead.”