Nearly half the people on Earth use wood or coal to cook their food, and every year three to four million people die from illnesses related to fuel used for cooking.

"People burn these inefficient fires usually in their home," Danny Wilson, a development engineer at the Lawrence Berkeley National Laboratory, told Seeker. "They're producing a lot of smoke, it's as if you were barbecuing right there in your kitchen. And they're doing that three times a day, every day."

Cooking and heating sources are also a key contributor to Africa's air pollution crisis. From 1990 to 2013 outdoor air pollution rose to 36 percent across Africa, causing an increase in pulmonary and respiratory diseases like heart attack, stroke and lung cancer.

WATCH: For 3 Billion People Cooking Can Be Deadly

Wilson and his team are trying to build new cookstoves with efficient designs and distribute them to places like Sudan, Darfur and Ethiopia where this problem is prevalent.

"The cook stoves are designed to really satisfy two important needs for people," Wilson told Seeker. "One is to reduce the amount of fuel that people have to burn to cook their food, then the second objective is to reduce the amount of smoke that people are exposed to."

Last year, Seeker's Laura Ling visited Tanzania and witnessed this problem firsthand. She met a woman named Mwanaidi in the rural part of the country, who said she uses firewood to cook everything.

"I use the firewood to cook tea, ugali, rice, vegetables and to boil water for the kids," she said. "When the smoke enters my eyes it hurts. Then tears start to come out," she said.

Mwanaidi knows regularly inhaling smoke is a health risk, but wood is her only available fuel source.

RELATED: Which Are The Most Polluted Cities in The U.S.?

While cookstoves are a key contributor to deaths from air pollution, in many African countries pollution from traffic and power generation are an even larger contributor to fatal illnesses. In addition to air pollution, Africa continues to deal with rampant issues like unclean water, unsafe sanitation, malnutrition and an energy crisis, making it difficult to tackle each problem individually.

In Sudan and Darfur, international conflict has raged since 2003, and two million people are living in camps where it's difficult to find fuel for cooking.

"When your life centers around a seven hour walk to go get wood and bring it back home, it's very hard to make space for education, business, or entrepreneurship, time and energy invested in kids, etc.," Wilson said. "This problem is not only a health crisis, it's also an economic crisis, and I think of it as a crisis of drudgery."

Wilson's stove, called the Berkeley-Darfur stove, burns wood but reduces fuel use by 50 percent. Wilson and his team are continuously testing and updating their design as well. Thanks to data they receive from a sensor attached to each stove, they're always working to make them more efficient.

RELATED: 92 Percent of the World Breathes Polluted Air

It's estimated that three billion people worldwide cook and heat their homes using inefficient and dangerous sources of fuel.

"Because the problem is so large, there is a very large potential impact," Wilson said. I can see how the decisions that I'm making as a designer or the decisions that partners are making in the field are influencing people's lives. It just gives me energy and excitement to keep on going."