A race-track single-core fluxgate magnetic gradient sensor has achieve
d a noise level of 30 pT cm(-1) r.m.s, (50 mHz-10 Hz) with a gradiomet
ric base of only 3.75 cm. Such a sensor has sensitivity high enough to
replace SQUIDs in the detection of ferromagnetic particles deposited
in human lungs. Measurements on tissue samples, dust from respiration
fitters and experiments with phantoms have proved that the total amoun
t and spatial distribution of dust in the lungs may be measured in the
case of welders, grinders and other metal workers. Measurements on co
al miners and asbestos workers are less specific. The construction of
the magnetization device for in vivo experiments is in the progress.