Video: Mass evacuations in Buenos Aires due to toxic cloud Office buildings in the Buenos Aires were evacuated as toxic gas cloud covered the city's business district and port area. The cause of the foul smelling smoke was thought to be the result of a shipping container fire at the city's central port. An intense sulfur-like odour, combined with mild eye and respiratory irritation caused many people to flee offices and homes. While the exact content of the container was still under investigation, officials claimed that it was only mildly toxic and did not pose any immediate health risks. The emergency manuals say that this product is mildly toxic, that it only causes irritation to the mucous membranes and skin. Obviously, the investigators are going to take samples to verify that the actual contents of the container correspond to what is listed. But, at this point it seems that we are dealing with a solid carbonate, something that has a low level of toxicity," said security secretary, Sergio Berni. Subway and train services to the affected neighbourhoods were suspended or delayed. As a precautionary measure, residents were advised to remain inside and close all windows and doors.