Styrene, which leaked from the plant, reacted with oxygen in the air to form higly toxic styrene dioxide
Environmentalists have advised everyone living in close proximity to the LG Polymers factory in Vishakhapatnam, where a styrene gas leak killed 11 people, must be immediately evacuated as the chemical is highly toxic and may have severe health impact - in the long and short run.
Sunita Narain, director general at the Centre for Science, said styrene can be more dangerous if it reacts with oxygen in the air and converts into styrene dioxide.
She said evacuation of people is needed and advised they should wear wet masks to protect themselves from the toxic gas.
According to India's Manufacture, Storage and Import of Hazardous Chemical Rules 1989, styrene is classified as a "hazardous and toxic chemical".
Anumita Roychowdhury, Executive Director, Transport, at the Centre for Science and Environment (CSE), said air is the medium and the styrene gas is toxic and it is this kind of exposure that has caused huge harm.
CSE researcher Soundaram Ramanathan said the gas is still in the air and even in its mild form can have health effects on people so the general practice is to wear wet masks and stay careful till the local environmental authorities say that the effect has gone and things are back to normal.
"The effect can last for a few days. People should be very careful at least for the next three days. If possible nearby areas should be evacuated but it will be difficult in the present situation," she said.
Due to the fear of coronavirus, people are mostly staying indoors and it can help if they have filters or are disinfecting their houses, Ms Ramanathan said.
She said short term exposure to the gas can result in eye irritation, gastrointestinal effects while chronic long term exposure can affect the nervous system. "If it goes beyond 800 ppm then the person can go into coma," she told PTI.
Sunil Dahiya, analyst with Centre for Research on Energy and Clean Air, said one of the reasons such things happen in India is due to negligence to environmental regulations.
"In terms of protecting themselves, people experiencing symptoms should immediately reach out and wear wet masks. In the long term these kind of gases will impact you for years and there must be immediate evacuation of people from exposure areas," he said.
"Styrene can stay in the air for weeks. It is highly reactive, it can combine with oxygen to form styrene dioxide which is more lethal. The presence of other pollutants can also affect the reactivity. On a sudden note operating one reactor in full load can also lead to such disasters," said Thava Palanisami, Senior Scientist, Global Centre for Environmental Remediation (GCER) & CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), University of Newcastle, Australia.
The CSE, in a statement, said the duration of the exposure and its relative concentration will determine toxicity.
"We currently know that roughly 3 tonnes of the gas leaked from its storage tank and the feeding line. We now need to determine the exposure," the CSE said.
Environmentalists said it seems that the gas leak occurred as the plant management, in its haste to re-start the plant, ignored the protocol of conducting maintenance of the plant before resuming operations.
"This, combined with the lack of proper storage of the gas - not maintained at the temperature required - and faulty fixtures could have resulted in the accident. The lesson for COVID times -- Vizag could be just a tip of the iceberg," the CSE said.
They advised that an immediate directive must go to all units to ensure safety while resuming operations, and these safety precautions must not be negated in case the lockdown continues.
A specialised CBRN (chemical, biological, radiological and nuclear) team of the National Disaster Response Force (NDRF) and medical specialists are being rushed to Vishakhapatnam where 11 people have been killed and about 1,000 affected due to the gas leak at a chemical factory, the centre said on Thursday.
Till now, 500 people belonging to almost 250 families living within a 3-km radius of the factory have been evacuated to safer places.