Almost 3 billion people worldwide use biomass and coal
as their main source of energy for cooking, heating, and
other household needs, so the population at risk worldwide
is very large. In these communities, indoor air pollution is
responsible for a greater fraction of COPD risk than SO2
or particulates from motor vehicle emissions, even in cities
densely populated with people and cars. Biomass fuels
used by women for cooking account for the high prevalence
of COPD among nonsmoking women in parts of the Middle
East, Africa, and Asia34,35. Indoor air pollution resulting from
the burning of wood and other biomass fuels is estimated
to kill two million women and children each year36.