Hazy outlook – Workers install seats by part of the Formula One street circuit for the night Singapore Grand Prix, which takes place on September 20, as a haze shrouds the city skyline. Organizers say the event will go ahead, with air quality forecast to improve in time.
Lighting the way – Floodlights pierce the atmosphere to reveal the layout of the race circuit. The haze is caused by farmers in neighboring Indonesia burning forests to clear land, with air quality dropping to unhealthy levels. Paper and palm oil firms are also criticized for the practice. Swathes of Indonesia, Singapore and Malaysia suffer from the resulting air quality problems.
Ferrari's Sebastian Vettel will start the 2015 race from pole position.
Familiar scene – Smog shrouds the track in 2014 in this aerial view of the drivers' parade before the start of the Grand Prix.
Clouded outlook – A closer look at the Marina Bay Circuit during the 2014 drivers' parade.
Covering the waterfront – The Singapore waterfront stadium and Formula One racetrack are blanketed by haze in the final days of the build-up to the 2014 race.
Lew's the man – Lewis Hamilton poses on top of his car after winning the 2014 Singapore Grand Prix.
Recurring theme – The haze problem has been ongoing for many years -- this 2006 image shows Singapore's skyscrapers enveloped in smog. Experts have warned that the annual recurrence of carbon-rich haze caused by fires in Indonesia could fuel global warming if not stopped.
Lurking in the shadows – Malaysia is also heavily affected by the haze spreading from its neighbor, seen here in 2013 as motorists drive past the smog-enveloped Petronas Towers in Kuala Lumpur.
Covering up – A woman helps her friend with an anti-pollution face mask in Kuala Lumpur. Masks will be made available to fans at the Singapore Grand Prix, authorities have announced.
Precautionary measures – Students in Kuala Lumpur don masks during the 2013 haze -- a situation that led to states of emergency being declared in some areas of the country.
Escaping the smog – A woman walks through a smoky haze in Siak Regency, Riau Province, Indonesia, during the burning of forests there in 2013. Eight farmers were arrested for setting fires on Sumatra Island, and fires are also common on Borneo.
Rays lowered – Construction workers labor against the backdrop of a hazy sun In Medan, Indonesia. The province declared a state of emergency when smogs worsened in 2013.