Soldiers help residents retrieve basic necessities from their blasts-damaged homes during rains in Tianjin Binhai New Area on Tuesday morning. The residents were temporarily allowed to go back home after massive explosions hit a warehouse in Binhai New Area in Tianjin on Wednesday night, Aug 12, 2015. [Photo/ wj.81.cn]

Rain Tianjin currently is experiencing does not pose any imminent risk to people's health, and an evacuation will be ordered if necessary, Bao Jingling, chief engineer of Tianjin's bureau of environmental protection, said at a news conference on Tuesday morning.

The first rainfall hit the blasts scene in Tianjin Binhai New Area at around 10:30 am Tuesday morning, prompting fears that rainwater could be polluted by toxic chemicals remaining at the site and contaminate surrounding areas and affect the health of the public.

Bao said toxic chemicals could be released into air when chemical residues on the ground are touched by rainwater, resulting in indirect pollution in air. As long as there are no further blasts, there will be no direct pollution to air, he added.

"Once we detect an excessive level of cyanide or organic compounds in air, we will timely issue notice, and the best solution for now is to stay away (from the blasts site)," said Bao.

Bao said the rains will also take away some of the toxic chemicals into drainage, and the government has blocked the access to sea and rivers to prevent further contamination.

"We will keep a close eye on environmental index. Once any irregular data is found, emergency measures will be conducted," he said.

Earlier reports claimed that the municipality have artificial mitigation measures ready against possible rain so as to prevent chemical reactions between sodium cyanide and water, which, however, was rejected by the municipal meteorological bureau, who said they don't have artificial mitigation plan for Tuesday and they have never had such plans since the blast, according to Caijing.com, a financial news portal.

Experts said people could feel choking after inhaling minor amount of oxygen being contaminated by sodium cyanide gas, according to a report carried by Caijing.com, a financial news portal.

Previously, photos depicting Premier Li Keqiang and other officials visiting the blasts site on Sunday showed Li not wearing masks or taking any other protecting measures, in a gesture to demonstrate the leadership's confidence in local air quality, experts said.

People worry that rains might complicate rescue efforts and spread pollution in Tianjin port, which was rocked by the blasts last week.