It is a terrible fact of life after 9/11 that we now more fully understand the elements of a terrorist attack. It involves a weapon, a target and a terrorist. In London, Madrid, Islamabad, Mumbai and Bali, the elements were separate and distinct. In some cases, however, the weapon and the target could be one and the same.

While the protection of all critical national infrastructure is important, chemical plants represent a special subset of those assets. The chemical sector is a critical part of our nation’s economy, employing more than 1 million people and accounting for more than $550 billion in annual revenues. At the same time, many chemical facilities produce and maintain hazardous chemicals that if released as a result of a terrorist attack would cause significant harm to facility workers and the surrounding population.

As a country, we recognized similar dangers when it came to nuclear power plants, aviation, ports and rail systems, as enhanced security measures have been put into place over the past several years in all of these sectors.

To respond to the threats in the chemical sector, in 2007, the Department of Homeland Security enacted the Chemical Facility Anti-Terrorism Standards, placing chemical facilities into tiers based on risk. The intent was for the department and industry to collaborate on measures that would ensure the security of these facilities. To date, of more than 36,000 facilities, the department has determined that 7,000 will be regulated, with about 150 now placed in the highest risk tier.

The Department of Homeland Security has done an admirable job in promulgating and enacting CFATS, but the department’s authority sunsets in the fall. Congress has the responsibility to act in order to ensure the continued security of the nation’s chemical facilities and the communities around them.

Last week, we introduced a bill that not only makes the CFATS program permanent but strengthens it by making facilities, as a part of their site security plans, analyze how they can switch to safer chemicals or processes to reduce the consequences of a terrorist attack. By reducing the amount of a dangerous chemical used on-site, for example, a company can make its facility less desirable as a terrorist target. The bill will require the highest-risk facilities — those that would endanger the most people in the event of a terrorist attack — to switch to safer chemicals or processes when feasible.

Existing law exempted several classes of facilities, including drinking water and wastewater facilities and most facilities located at our ports, a security gap identified by the Department of Homeland Security. This bill will ensure that port facilities and wastewater facilities meet the same standards as other chemical facilities. We will work to ensure that the Department of Homeland Security and Environmental Protection Agency work together to develop and enforce these standards.

The time for action is now. We have an opportunity to ensure this vital industry, the men and women who work in these facilities, and the population that lives around them are safe and secure. We understand the threats, and we know enough to act on them. We must seize the initiative to work together to secure our infrastructure, our economy and the lives of our citizens.

Rep. Bennie Thompson (D-Miss.) is chairman of the House Homeland Security Committee. Rep. Henry Waxman (D-Calif.) is chairman of the House Energy and Commerce Committee. Rep. Sheila Jackson Lee (D-Texas) is chairwoman of the Homeland Security Subcommittee on Transportation Security and Infrastructure Protection. Rep. Ed Markey (D-Mass.) is chairman of the Energy and Commerce Subcommittee on Energy and Environment.