After more than a week of haze in Singapore, hail storms, wind, and rain offered much needed relief from the choking amounts of smoke that has broken air pollution records and cost an estimated $1 billion in losses from damages and lost tourism.

"The torrent came in a five-minute burst; something was clanging on my windows and I went to my front door to see what was going on," Lucas Ho, a playwright and teacher, told The Straits Times. "I never thought I'd see hail in Singapore."

A number of other Facebook users and contributors to the citizen journalism website, Stomp, also sent photos and videos of the hail, which Singapore hasn't seen since 2008.

"Hailing in Singapore! I thought stones were flung into my balcony when I saw it was ice cubes," Foo, a contributor, wrote.

Kent, another contributer, also wrote in, saying," The welcomed downpour came with ice!"

Moderate to heavy thundershowers with gusty wind are expected over southern, eastern, and central Singapore. When hail started dropping, the National Environment Agency (NEA) assured residents that it was not toxic, or even related to the haze. Luckily, the wind was blowing the haze away from Singapore at the time.

Singaporeans welcomed the change of weather after more than a week of record breaking air pollution levels and choking haze. Caused by widespread forest fires in nearby Sumatra, the haze broke Singapore's previous Pollutant Standards Index (PSI) of 226, which it hit during the 1997-1998 dry season, reaching as high as 401 on Friday. Anything over 300 is considered hazardous to breathe — Singapore's government even said a reading of over 400 sustained for 24 hours "may be life-threatening to ill and elderly persons."

The fires that caused the haze are caused by a number of hotspots on Sumatra, one of the islands of Indonesia. These hotspots are peat and forest fires, which started because of the country's dry season, but were illegally exploited by companies looking to build oil palm plantations on the land.

But the haze comes at a huge cost to Singapore residents. A study found that land-clearing fires and their pollutants in the atmosphere pushed air quality levels in Malaysia and Indonesia 300 percent past World Health Organization (WHO) limits for almost 200 days of 1997. The researchers estimated that these levels could result in about 15,000 deaths — not including infants and children. Between 1997 and 2006, they found that between 5.4 million and 60 million people were exposed to particulate matter (PM) and ozone levels above WHO recommendations.

Although the World Health Organization (WHO) found that there is no safe level of PM under which no damage to health occurs, The WHO Air Quality Guidelines estimates that by reducing PM levels from 70 — the world average — to 20 micrograms per cubic meter, air quality related deaths will be reduced by 15 percent.

Air pollution has short term consequences too. The Environmental Protection Agency (EPA) says that excess ozone — a component of smog — can cause chest pain, coughing, throat irritation, and congestion. It can also reduce lung function, especially in children, because their lungs are still developing and they tend to play outdoors more frequently when ozone levels are high.

Source: Marlier M, DeFries R, Voulgarakis A, et al. El Niño and health risks from landscape fire emissions in southeast Asia. Nature Climate Change. 2012.