Chlorine makes human life safer. Its most universally recognised application is in water treatment for human consumption, considered by many to be one of the greatest discoveries of the last millennium, without which the history of humanity would have been substantially different. But its importance goes far beyond this extraordinarily important or even decisive application.

As an infiltrating agent, chlorine is present, but not visible, in thousands of products that are part of our day-to-day lives. Through integration into essential chemical compounds in the most diverse production processes, its scope is remarkable, as is the impact of its dozens of derivatives.

The so-called "chlorine tree", graphically illustrating the branches (derivatives) and fruits (products) obtained from this chemical element, highlights its importance in a crucial area of society – safety in its broadest sense.

The airbag system, a safety component of a car, uses hydrazine, a chlorine derivative, as one of the gases that allows it to expand in a crash. Chloroethanol, on the other hand, is the basis for the manufacture of the polyester that makes up safety belts, an element estimated to have saved more than a million lives on the road since it was invented in the 1950s.

In cars and other vehicles, another key application is chloropropanol in brake fluids, a compound that has long been widely used in hydraulic braking systems.


In nautical activities, another chlorine derivative, dichlorobutane, gives rise to adiponitrile, which is an intermediate in the production of nylon. Among countless other applications, nylon can be used to manufacture life jackets, whose function and importance is widely recognised as a last resort for survival in the event of an accident in the aquatic environment.

Chlorine and its derivatives are also of fundamental importance in the manufacture of Personal Protective Equipment (PPE), which is essential in military, security and civil protection activities, as well as in other work functions with high physical risk.

Bullet-proof vests and protective gloves, for example, incorporate telephthaloyl chloride, a key component in the manufacture of high-performance polymers (such as kevlar) and aramid fibres, offering great physical resistance to fire and chemical attacks, among other advantages.

Suits used for high-risk activities, such as firefighters or racing drivers, contain isophthaloyl chloride, as do military and police suits, giving them high resistance.

Phosgene also plays an important role in this field, as a basic element in the production of polycarbonate, which is used in the production of goggles and bulletproof glass.

Chlorine has also proved to be a precious ally in serious public health situations, both from a preventive and curative perspective, helping to save lives and maintain social order.


As the active principle in sodium hypochlorite, it has, for example, been of fundamental importance in the fight against Covid-19 as a disinfectant agent for public and private spaces, as well as in the fight against viral infections with major impact in terms of public health, such as those caused by the Zika or Dengue viruses. Its importance as a powerful deterrent to the spread of Legionella should also be highlighted.  


Carl William Scheele, the Swedish chemist who discovered chlorine almost 250 years ago, would certainly not have imagined that he was laying the seed for the advent of something especially important in our daily lives, and which is illustrated by the "chlorine tree". As in several other fields, this tree also extends its branches far with regard to security matters – from personal to public protection, from the defence of the common good to the maintenance of physical integrity in more radical leisure activities.


Portugal has, for several decades, played an important role in the production of this social guardian. With production units in Estarreja and Torrelavega, in the north of Spain, Bondalti is today, in terms of installed capacity, the largest Iberian producer of chlorine, which is obtained through the electrolysis process, using the best techniques and technologies available and in accordance with the highest environmental requirements.