In a statement, 21 NGOs said the fire could have led to significant atmospheric methane emissions, posing short- and long-term health risks.
They said natural gas was primarily composed of methane, a potent greenhouse gas with much higher global warming potential than carbon dioxide.
“Methane can reduce the amount of oxygen in the environment and induce health issues such as slurred speech, vision and memory loss, nausea, vomiting, and headaches,” they said.
The groups said a US study also found that leaks from gas pipelines could lead to the emission of atmospheric chemicals, including PM2.5 and PM10, volatile organic compounds, ozone, and nitrogen oxide.
“These hazardous chemicals are known to cause longer-term impacts as well, including worsening respiratory disease and increased respiratory, cardiovascular, and cerebrovascular mortality.”
The groups urged Putrajaya to ensure that investigations into the incident are transparent and the results are released in full to the public.
They also asked that the results of air quality monitoring in the area be released to disclose the impact of the fire, and for methane emissions from the blaze to be revealed.
“We call on the government and Petronas to commission an independent study into the short and potential long-term health and safety impacts of the incident, benchmarked against World Health Organization standards.
“This study should be made public, and Petronas should provide full healthcare coverage for both local communities and first responders.”
The statement was prepared by green groups RimbaWatch and Greenpeace Malaysia, and endorsed by groups like Sahabat Alam Malaysia, the Consumers Association of Penang, Pusat Komas and the Center to Combat Corruption and Cronyism.
Separately, the environment department said the air quality in the area was not at an unhealthy level, and there was no abnormal rise in the air pollutant index (API) following the blaze.
Its director-general, Wan Abdul Latiff Wan Jaffar, said the department would increase surveillance on the ground and in the air, with the deployment of drones to monitor the API in the area.