.when robert had to go on full medical disability in his early 50s after hurting himself at work, helen went back to work, this time in the oil industry.. .in particular, the country has extreme levels of nitrogen dioxide due to heavily congested roads in urban areas,...he said: "greater and immediate attention needs to be applied in these two areas.".elizabeth loder, md, professor of neurology, harvard medical school; chief, division of headache, brigham & women's hospital.