Having elevated levels of the heavy metals lead and cadmium does result in an increased incidence of asthma, as demonstrated in recently published research from Brown University.
Elevated lead levels can be seen in children living in homes with old-fashioned lead paint, and in adults with workplace-exposure to lead fumes.
Elevated cadmium levels are typically only seen due to industrial workplace exposure.
The heavy metals cause a shift in TH1/TH1 response, thus leading to much greater production of IgE, the allergic antibody that causes asthma.
The next phase of the research at Brown University if to see if reduction in the heave metals in the blood stream leads to amelioration of the asthma.