Question

what is the greatest source of indoor air pollution in less - developed countries? poorly ventilated cooking fires air conditioning units

Explanation:

In less - developed countries, many households rely on traditional cooking methods using solid fuels (such as wood, coal, dung) in poorly ventilated spaces. These cooking fires release a large amount of pollutants (like particulate matter, carbon monoxide, etc.). Air - conditioning units are less common in less - developed countries compared to the prevalence of traditional cooking methods.

Answer:

Poorly ventilated cooking fires