Smoke rises over damaged containers and cars after a huge explosion rocked the port city of North China's Tianjin, August 13, 2015. [Photo/CFP]

The environment outside the core zone of the Tianjin blast site remained normal despite the rainfall over the past two days, authorities said on Tuesday.

The site is still being cleaned up.

Fire started again at the site on a rainy Monday night, as certain chemicals that ignite when coming in contact with water-magnesium and sodium metals－got wet. Experts at the scene who were quoted by Tianjin Daily said the fire was under control and was not unexpected.

The smoke from the fire is not toxic, the authorities said.

As of Tuesday afternoon, the blasts that rocked a warehouse storing hazardous chemicals had claimed 159 lives, including 95 firefighters, and left 14 missing. A total of 321 people are still hospitalized, and four are in critical condition.

According to the Tianjin Information Office on Tuesday, the quality of water and air were normal outside the core zone on Monday.

Meanwhile, cyanide levels in four of the 21 water-monitoring stations in the core zone exceeded the national standard, with the highest concentration 31.4 times the standard.

According to the official micro blog of the Tianjin Binhai New Area on Tuesday morning, the command center has a detailed response plan in case of rainstorm, including digging open trenches and strengthening the waterproof barrier surrounding the core zone.

It has also prepared 50 vehicles to move excess water in case the level rises too fast.

No rain is forecast from Wednesday to Friday.

Vice-Premier Zhang Gaoli, who served as the top official in Tianjin from 2007 to 2012, has paid great attention to the ongoing work and emphasized that dealing with rainy days is an important part of an emergency plan, the Information Office said.

Chen Sheng, an official with the State Council's Emergency Management Center, visited the blast site on Tuesday and urged that toxic water be prevented from flowing into the sea.

Huo Bin, head of the land and resources management department of Tianjin Binhai New Area, confirmed on Tuesday that if occupants of affected households want to buy a new apartment, the new residence will be considered as a first one under mortgage policies.

More than 5,000 apartments in the area are available for purchase, and the government has asked property developers to set prices no higher than they were before the accident, according to the Information Office.