The bustling city-state of Singapore has been enveloped by a thick haze over recent days, thanks to winds bringing in smoke from forest fires in neighbouring Indonesia that are sparked by companies to clear plantations and farms. 

More than 2,000 Singaporeans had to seek treatment related to problems from the haze in one week alone, and the government had to shut schools for several days and close several tourist areas as pollution levels breached the safety limit.

On Thursday, the Pollutant Standards Index (PSI) stood at 317, indicating 'hazardous' air, and it climbed to 341 on Friday, according to the National Environment Agency. The health hazard threshold is 300, while anything above 200 is considered 'very unhealthy'.  

According to Singapore's health advisory, citizens are advised to cut down on outdoor activities when pollution levels cross 100. This year, the pollution levels may cross the record air pollution index of 401 reported in June 2013.

Singapore has now taken legal action against five Indonesian companies said to be responsible for the plantation fires, after it passed the Transboundary Haze Pollution Act last year that allows it to fine any foreign entity up to $70,000 for contributing to air pollution in the city-state. 

Here are some pictures to show how the haze has affected Singaporeans -