The Nuclear Regulatory Commission approved a regulation Thursday that tightened radiation-exposure limits for nuclear plant workers and residents near atomic power installations.

Then, in 1988 and in 1993, Congress again tightened limits on what executives could get from regular pension plans.

Pfizer Limits Canadian Sales Pfizer tightened limits on sales of its products to Canadian pharmacies in an effort to reduce imports by United States consumers.

The rules, which tighten limits on certain smokestack emissions, are designed to enable lakes, streams and forests polluted by the corrosive rain to repair themselves naturally.

This concept assumes that if a country has tighten limits than other, or if it declares explicitly a limit, then the regulation could be considered more stringent.

In a series of closed meetings, supporters of efforts to tighten limits on gifts failed to make much progress towards compromise with foes.

The recent security crackdown that tightened limits on carry-on luggage serendipitously proved her point.

The proposals in Colorado and Utah would significantly tighten limits already adopted; the six other states have no Congressional term limits.

A measure to tighten conflict-of-interest limits on former government employees received 82 percent of the vote.

The proposal, called the interstate air quality rule, would gradually tighten limits on emissions of nitrogen oxides and sulfur dioxide through 2015.