Streets around Notre Dame Cathedral in Paris are shut down to be decontaminated for lead

City officials in Paris shut down the streets surrounding the Notre Dame Cathedral on Tuesday to begin decontaminating the area for high levels of lead.

The Notre Dame Cathedral caught fire on April 15, destroying the structure’s spires and parts of the roof. Tons of lead from the structure melted from the fire, and the particles spread to the surrounding areas.

“After the melting of at least 300 tons of lead in the gables of the spire and in the roof, Notre-Dame de Paris is now a polluted site,” French environmental group Robin des Bois said in a statement. “The cathedral has now become filled with toxic waste.”

Work to renovate the cathedral was put on hold July 25 in order to improve the protection of workers from lead pollution. Equipment and procedures are being installed to ensure the safety of the workers and to better control access to the site in order to prevent any polluting elements from escaping.

“Our priority is to prevent any risk to employees working on the site,” Paris prefect Michel Cabot said. “With new safety protocols and the delivery of two new decontamination units, the quality of lead decontamination of workers, machinery and equipment will be optimized. Thus, the site will continue to be safely ramped up.”

Officials expect the construction site to resume operations on August 19. However, the streets surrounding the cathedral will take more time. The decontamination operation is expected to roll out in three phases and take three to four weeks, according to city officials.

Cleaners will use an absorbent gel and high-pressure water jets to clean the area of lead, dust and other fallout from the fire.

President Emmanuel Macron has set a five-year goal to complete renovations on the 850-year-old structure, and approximately 850 million euros ($955 million) in donations has been pledged to help restore the cathedral.