Beirut is probably covered in potentially harmful dust particles, despite the cloud of pollutants and nitrogen dioxide produced by Tuesday's blast clearing, a leading Lebanese expert has warned.
No full scientific analysis of the debris at Beirut port has yet been done, said Najat Aoun Saliba, a professor of analytical chemistry and the director of the Centre for Nature Conservation at the American University of Beirut.
Prof Saliba said a quick study showed there was no uranium or other radioactive substances.
But she said potentially harmful ammonium dust, finely ground debris and glass dust could be coating much of the city.
“I think, environmentally, what worries me now is the diversity and the waste generated from glass powder and from the dust that is going around in the city,” Prof Saliba said.
“And now people are trying to clean up the mess in front of their homes, and you can see roads covered with glass and even powders. This is extremely dangerous if inhaled.”
She said people should wear masks and gloves and spray water to settle any airborne particulates.
But Prof Saliba said cheap paper masks would not be able to filter out the finest and potentially most harmful dust.
“I'm telling people that the precautions you take for the pandemic you need to keep them and actually double down on them,” she said.
Prof Saliba said thick gloves should be worn when handling dust, along with a face shield or goggles to stop it getting into eyes and heavy-duty masks to prevent inhalation.
She little was known about what chemicals were in the toxic fire and what might still be around the city.
“Chemically speaking, ammonium nitrate on its own will produce nitrogen dioxide and we saw that with the brown smoke over Beirut on the night of the blast,” Prof Saliba said.
“What we know today is that the brown smoke that was there on the night of the blast has dissipated.”
That does not mean the city is now safe.
“We need the inventory of what was there during the blast and we need to take samples from the ground,” Prof Saliba said.
“What are the other chemicals that were burning with the ammonium nitrate? I'm sorry, I don't have an answer for that because we were not able to do thorough chemical analysis.
“We don't know whether there are other chemicals stored in addition to what they’re saying.
"We need a clear mapping of the industrial facilities in the area and for the material that was stored in the containers.”
She said that air-quality monitors at her university picked up the surge in particulates and pollutants to hazardous levels straight after the blast.
But Prof Saliba said these dropped within hours as wind cleared the air.
While they could be harmful in large quantities, she said they were not uncommon in the polluted city.
“Sometimes when we get dust storms from the desert close by, we get to this level," Prof Saliba said.
"But what is more important is the amount of nitrogen dioxide.”
She said that gas was very dangerous.