In the first six months of this year, ozone reached unhealthy levels on 13 days.

Many electric fountains for drinking water in schools and other buildings are exposing people to unhealthy levels of lead, a House panel was told today.

Hoarders, however, take collecting to an entirely new, and often unhealthy, level.

The radon could then, if ventilation is inadequate, build up to very unhealthy levels.

Unfortunately, it could add to superstition, which is already prevalent at an unhealthy level in our country.

Many fear greenhouse gases are warming the atmosphere to unhealthy levels.

Several categories of drugs can help to control unhealthy levels of blood lipids.

The influence of special interests is now at an extremely unhealthy level.

It added that "visitors would likewise want to minimize their exposure to what are likely extremely unhealthy levels of air pollution."

Athletes at the elite level will sometimes attempt to temporarily lower their body fat to unhealthy levels to give themselves an edge in important competitions.