Choked by the haze and as the Pollutant Standards Index climbed to as high as 300, some members of the public called for a boycott of palm oil products. Errant oil palm plantation owners set fire to adjacent forests to open up new land for cultivation.
Some also do this to clear their plantations after a crop cycle.
According to the Roundtable on Sustainable Palm Oil (RSPO), a recognised palm oil certification body, of the many fires that happened in Indonesia last month, 1,400 were within oil palm plantations.
To prod shoppers into action, global body Consumers International, a not-for-profit company based in Britain, last week called for people to stop buying items made by firms contributing to the forest fires in Indonesia.
A Straits Times street poll this month seemed to show that consumers - half of the 50 surveyed - would stop buying products from firms contributing to the haze.
But first, they need to know how.
WHAT'S ON A LABEL
The toothpaste that you brush your teeth with each morning and night, with that minty freshness, probably has palm oil in it.
Experts say that half of all products on supermarket shelves here - from cosmetics to ice cream and potato chips to biscuits - do too.
But you, the consumer, would not know it.
The key reason is that, unlike many other developed countries, Singapore does not require those who sell products here to list palm oil as a specific ingredient on labels.
A check with the Agri-Food and Veterinary Authority (AVA), which regulates food labelling here, found that generic terms like "vegetable oil" and "vegetable fat" can be used on packaging to disguise the use of palm oil.
It is necessary to declare the source of an ingredient if it is known to cause hypersensitivity, say, in the case of soy lecithin, commonly used as an emulsifier in food production.
Palm oil, said the AVA in response to queries from The Straits Times, is not known to cause hypersensitivity in individuals.
Laws are different elsewhere.
As of December last year, all food items sold in Europe must list palm oil in their ingredients if it is in the product.
In Canada, palm oil is one of five vegetable oils, along with palm kernel oil, coconut oil, peanut oil and cocoa butter, which must be specifically named in a food product.
In Australia, the government is reviewing the labelling practices for palm oil in food, which now allow it to be listed as a vegetable oil.
THE ISSUE WITH PALM OIL
Palm oil is not unsafe to eat - although it has a saturated fat content of over 50 per cent, which fares poorly in comparison with other vegetable oils like canola - but its sale has sparked dramatic demonstrations around the world.
In March last year, Greenpeace activists ziplined across Procter & Gamble's headquarters in Cincinnati to unfurl giant banners; and in 2008, activists dressed as orang utans climbed onto the roof of Unilever's headquarters in London.
Groups, like the United States' Palm Oil Consumers Action, have also raised awareness of the negative impact of unsustainable palm oil.
The burgeoning palm oil movement has forced firms like Unilever to use only palm oil from sustainable sources.
The World Wide Fund for Nature (WWF) said that between 1990 and 2005, as much as 60 per cent of oil palm expansion was at the expense of natural forest, some of them the most ecologically diverse in the world and home to endangered species including the orang utan and the Sumatran rhino.
By 2020, the use of palm oil is expected to double, as the world's population increases and people - especially in places like China and India - become more affluent and consume more manufactured goods.
According to the RSPO, as much as 80 per cent of global palm oil is currently not certified.
"While we are sure about the origins and the sustainability criteria under which 20 per cent of global palm oil is produced, we are not able to claim the same for the other 80 per cent," the global outreach and engagement director of RSPO, Mr Stefano Savi, told The Straits Times.
RSPO-certified palm oil is produced under a strict set of environmental, economic and social criteria. These include ensuring that oil palm plantations do not replace forest or peatland - in other words, no burning is done.
WHO'S TO KNOW?
The culprits of forest fires are difficult to trace as supply chain processes are muddied by a lack of land ownership information in Indonesia and bulk processing, in which fruits from hundreds of small plantations are trucked to a central mill where they are mixed up.
Interestingly, despite the backlash against unsustainable palm oil, certified versions may not even be labelled as such, as it is not mandatory for firms with RSPO certification to mark their goods.
Mr Savi reckons only a handful of products here have the RSPO mark. There has been reluctance from manufacturers to carry the RSPO logo for several reasons.
First, palm oil typically makes up a small part of the formulation of a product, so few manufacturers feel compelled to specify its origin.
"Also, in certain markets, palm oil is not perceived positively, so companies won't want to emphasise that palm oil is in their products at all," said Mr Savi.
Try looking for "palm oil" on supermarket shelves here. Few such explicitly labelled items can be found.What this means is that, even if consumers know that the item they buy has palm oil in it, few will be able to tell if it is from a sustainable source.
COSTS OF LABELLING
Labelling, said Singapore Polytechnic senior retail lecturer Amos Tan, could be a trade barrier.
"Labelling requirements that are too onerous might deter companies from exporting to Singapore," said Mr Tan.
He added that Singapore distributors, who work with exporters overseas to import items to the country, will have to either source for products which already have the necessary palm oil labelling, or work with exporters to change the labels.
"This adds to cost," he said. The Republic imports over 90 per cent of its food supply.
When asked if it would consider tweaking regulations to make it compulsory for manufacturers to indicate the presence of palm oil in products here, the AVA said that Singapore is one of the 186 Codex members, representing 99 per cent of the world's population.
"Any regulatory change in a country's labelling requirements will have an impact on how the country imports or exports food products from other countries that follow the Codex standard," said an AVA spokesman.
The Codex, or the Codex Alimentarius Commission, is the international food standards setting body established by the United Nations Food and Agriculture Organisation and the World Health Organisation.
Other countries in the region including India and China also do not require manufacturers to list palm oil as a specific ingredient on their products.
But despite industry opposition to the new rule, the recent transition in Europe was largely manageable for businesses, who were given three years to make the change.
By the time the regulations came into force in December, many had already slapped on the new labels.
The Association of Chocolate, Biscuit and Confectionery Industries of Europe initially lobbied against the change. Its secretary-general Sabine Nafziger, however, was later reported in The Guardian newspaper as saying: "At first, people were nervous... But now, they are really happy to do it because it creates a level playing field."
Tweaking labelling regulations here could spark positive change.
It would, first off, give companies an incentive to source for sustainable palm oil and encourage those already using sustainable sources to promote this.
In the lead-up to the new regulations in Europe, for instance, sales of certified sustainable palm oil spiked 65 per cent, as firms prepared for the change and responded to consumer concerns about sustainability.
"If you know that a commodity is present in a product and that it may be associated with environmental issues, as a consumer, you will be able to pressure companies to source sustainably," said Mr Savi, adding that Singapore has been a front runner in the region in many aspects.
This, he said, could pave the way for change in nearby countries.
The move will also send a strong signal to firms that Singapore cares about where its food comes from.
It will also help to break ground for the Singapore Environment Council, which is working with the RSPO to launch a new green label certification for palm oil products here early next year.
Yes, the process of identifying sources of raw materials and attaining certifications does cost more. It might also lead to fewer varieties of food here.
But the haze has already impacted the lives of Singaporeans and others in the region. Scores of people have gone to clinics to seek treatment for respiratory ailments, schools have closed, and the volume of business has dropped. Tourism arrivals are also expected to plummet if the haze sticks around for much longer.
It is ironic that Singaporeans who want to stop contributing to the haze that is making them sick, cannot do so.
Surely, they have the right to make informed choices about the food and other household items that they consume and use on a daily basis.
After all, as Mr Savi said: "If you don't know that the commodity is in the product, there is little you can do."
Labelling palm oil in products here would not immediately lift the haze.
But it would be a good start.