In Asia, campaigners at the China International New Energy Vehicle show in Hong Kong this week have urged Asian countries to take an aggressive approach to fighting air pollution.
Part of the Chinese government's solution would be a transition from diesel-fuelled cars to clean energy vehicles.
International news agency Agence France-Presse (AFP) said that the city continues to battle with pollution levels, with the government’s monitoring system frequently measuring the air as "hazardous".
According to a 2013 Hong Kong University report, air pollution is the cause of death for 3,000 people every year.
Chief executive officer of Hong Kong-based Clean Air Network Kwong Sum-yin said: “In terms of air pollution in Hong Kong...this is really the biggest health crisis.
"All the Asian countries really need to act right now, otherwise we'll really reach the point of no return.
Mr Kwong added: "It's still the mentality to develop first and then fix the problem later, but we don't really have that timeline anymore."
Gov push towards clean energy vehicles
AFP notes that in a bid to reduce emissions, the Chinese government has proposed the replacement of 80,000 older commercial diesel vehicles with clean energy vehicles between 2014 and 2019.
The China International New Energy Vehicle show displayed the latest models from major Chinese manufacturers and French automobile manufacturer Renault.
"We need to have concrete cooperation from this conference," said former French prime minister Jean-Pierre Raffarin.
"We have to develop new initiatives the year after the conference and we have to act very quickly."
The smart car show took place as Paris prepares to welcome 147 world leaders to a climate summit to formulate a new international treaty to curb global warming.