According to Practical Action (formerly the Intermediate Technology Development Group), a United Kingdom-based organization that uses the principles of "small is beautiful" to help poor people in poor countries:
And therein lies the reason for one of El Porvenir's newer projects: helping families replace smoky open-fire cooking with modern, concrete, chimneyed two burner stoves, like the one pictured above.
In the Nicaraguan countryside, women who live in houses like this daily begin cooking tortillas at 4 am on open wood fires in the main (usually only) room. The smoke filters out the roof tiles, but not before women and children breathe it in, often all day long in the rainy season. Bronchitis and asthma are the chronic norms in such a setting.
This was the fire place in this house.
This picture, from a World Bank-financed evaluation of improved stoves [pdf] shows the dark, smoky interior environment.
El Porvenir aims to replace as many of those as they can with these. The replacements won't altogether solve either the interior air pollution or the over use of wood fuel, but among very poor people, every incremental gain can be a great benefit.