When a deadly cloud of chemicals being used to make pesticides killed thousands of people in Bhopal, India, in 1984, Americans wondered: Where could it happen here?

The U.S. government couldn't answer. All over the nation, factories, refineries and industrial plants were churning out vital products using toxic chemicals, but the companies didn't have to tell anyone what the hazards were. If something went wrong — a spill, a leak, a fire — emergency responders often didn't know what they'd encounter. Neighbors didn't know whether to take cover or evacuate.

Today, they do. Information on hazardous chemicals is a mouse-click away, thanks to the 1986 "Emergency Planning and Community Right-to-Know Act." An easy-to-use database includes specifics on 650 toxic chemicals that have the potential to cause cancer, neurological damage, or other health damage.

But EPA now wants to weaken those safeguards with two proposed rule changes. It wants to collect less data, less frequently. That would set back the clock, just when the public needs that information the most — in a time of increasing natural disasters, such as Hurricane Katrina, and the threat of terrorist attack.

The EPA itself brags that this public-disclosure law, which includes the Toxics Release Inventory (TRI), repeatedly has improved corporate behavior and empowered communities to protect themselves.

After Katrina, emergency workers and public-health advocates used the TRI to identify the possible threats in the air and water. By tapping into the database, officials instantly learned that New Orleans and its surrounding parishes host 66 chemical plants, refineries and petroleum bulk-storage facilities, containing a stew of more than 875 chemicals.

The TRI has been used similarly all over the United States. In Chicago, a citizens' group prompted an investigation into high lead levels from a neighborhood smelter. In Toledo, Ohio, environmental groups persuaded an alloy factory to reduce alarming emissions of beryllium, a toxic metal. In Colorado, the database is helping researchers study why chemical releases are more concentrated in the Rocky Mountain states than in the nation as a whole.

To reduce paperwork for industry, EPA proposes changing annual reporting to every other year, and raising the threshold for reporting pollution from the current 500 pounds to 5,000 pounds. With that change, 14 of 52 facilities in Philadelphia would no longer be required to detail information about their toxics. That would leave some neighborhoods where they were in the '70s — with little knowledge of their vulnerability to poisoning.

The TRI isn't a perfect tool. It's basically an honor system, dependent on companies' self-reporting. Information is already 2 years old when posted online.

But watering down the TRI won't make it better. America doesn't need a "right to guess" law.