In a study published in the journal Environmental Science & Technology last week, researchers found that improved cookstoves produced three times as many ultrafine particles of black carbon, also known as soot, smaller than 30 nanometers in diameter for a given unit of fuel compared with open fires. Ultrafine generally refers to particles than have diameters below 100 nanometers. In addition, the team discovered overall soot emissions per unit of fuel were similar across different stove designs.
They also typically use one half to one third as much fuel when compared to open fires, and the overall health benefits from improved stoves are massive... less CO in the atmosphere for a start, due to cleaner combustion.
No action, in any field, is wholly good... you can always point to a negative with everything. But this argument appears to be a slight of hand deflecting attention away from the big up front benefits.
If the increased efficiency of the stoves means they are used more, that will only be to give those households a better standard of living (warmth and such). That should be discouraged? What other means would they have to stay warm, and how much pollution would be created in producing it?
They say "study... found that designers could cut black carbon emissions from stoves using forced drafting." Yes, that sounds like a reasonable solution for millions (billions?) of households that don't have any electricity...