One major causative effect of asthma is the presence of cockroaches (of all species) almost always infesting the living areas of niggers. There was a scientific study done by epidemiologists about 30 years ago which concluded that the invisible dust of defecating cockroaches was "the primary effect of early childhood asthma among Negros". Sorry that I can't find that research on line, I suspect that (((they))) have redacted it by now.