BHUBANESWAR - On a hot, humid afternoon on the outskirts of Bhubaneswar in eastern India, construction worker Sabitri Mahanand frets about increasingly "dangerous" summers.

Carrying more than a dozen bricks on her head, she fears getting sunstroke while at work, but home offers no respite.

"When the day's work is over, I'm so exhausted that I often don't want to cook food but I have no choice," said Mahanand, 35, wiping the sweat from her face with a cloth wrapped around her waist. "I have to feed myself, my husband and my son."

The ancient city of Bhubaneswar is the capital of Odisha state - one of the few parts of South Asia that has a heat emergency plan.

Odisha's government departments have been asked to put in place measures in anticipation of heat waves this summer.

The world has already experienced three record-breaking hot years in a row, and the rising global temperature could have profound effects for health, work and staple food supplies for hundreds of millions of people, climate scientists told the Thomson Reuters Foundation.

The poor in urban slums in developing nations are particularly at risk, they said, while solutions to cool homes and bodies that do not hike climate-changing emissions remain elusive.

Even if the world is able to limit global temperature rise to 1.5 degrees Celsius above preindustrial levels - a goal set by governments in Paris in 2015 - by 2050, around 350 million people in megacities such as Lagos in Nigeria and Shanghai in China could still be exposed to deadly heat each year, according to a recent study by British researchers.

Fawad Khan, senior economist with ISET-International - which has conducted studies on heat stress, when the body absorbs more heat than is tolerable - describes heat as a "silent killer" and the world's "biggest impending climate-related hazard".

"First, your quality of life is going to deteriorate. You don't feel well, your children don't perform well at school, your physical and mental ability is affected," he said.

"The husbands work all day and come back tired and cannot sleep, children cry because it's too hot, and women say they have more domestic quarrels. These things take a huge toll, and they're immeasurable," he said.

Meanwhile, a new modular roofing system made with recycled agricultural and packaging waste, called ModRoof, may offer an option for cooling homes without using electricity.

Produced by ReMaterials, a company based in Gujarat, India, the roofs can lower the temperature inside by 6 to 10 degrees Celsius compared with metal and cement roofing, founder Hasit Ganatra said.

So far 75 roofs have been installed in Ahmedabad's slums, but they aren't cheap, with an average cost of $772 per family.

Ganatra said the company's all-women sales team is working with microfinance firms to make the product more affordable for the poor.