Firecrackers explode and thick smoke fills the air as seething farmers arrive at Brussels' door

Ahead of us, a ring of police protecting the European Parliament while acrid smoke billows over our heads. Firecrackers go off all the time, near and far.

The very heart of Brussels, normally populated by politicians, advisers and smooth-suited lobbyists, has been transformed into a cauldron.

A firecracker explodes too near for comfort. On the other side of Place Luxembourg, a hay bale is on fire. Next to it, a green flare has gone off. Then someone throws a rubber tyre on to the smouldering fire and thick black smoke starts filling the air.

To be in the middle of Brussels right now is a visceral experience of noise, smell, heat and sights.

And lacing it all, a sense of tension between those who have come to protest, and those who stand in their way.

For weeks, farmers have been demonstrating in their countries – blocking roads in France, Germany, the Netherlands, Spain, Italy and beyond.

The French farmers are today heading towards their own Parliament.

The Belgian farmers have only recently revved up their own tractors to join the protest, but the momentum is growing and now their own capital has become the focus of so much attention.

Read more on this story: Fires erupt during protests

There are reckoned to be a thousand tractors in the city today. I don’t remember ever seeing one in the city’s central European quarter before.

But none of this is a coincidence. The European Parliament is blamed for endorsing restrictive environmental legislation that has hindered farmers, slashed profits and increased bureaucracy.

And, increasingly, the focus of these protests is also being directed at the European institutions who have designed and signed free trade agreements with the rest of the world.

These have pushed down the cost of many items – grain, meat, vegetables, fruit, which may be good for consumers, but is palpably bad for farmers.

Another regular complaint is that some countries stick to the rules, forcing their farmers to abide with new regulations, while others turn a blind eye.

“Why should we have to suffer when farmers in Romania don’t have to do anything because nothing will happen to them if they break the rules,” said one French farmer.

And amid all of this acrid acrimony, Europe’s leaders are arriving in town.

At the European Council building, just a short stroll from the Parliament, the EU’s presidents and prime ministers are gathering to discuss a variety of topics, including their budget and their ongoing support for Ukraine – fitting, because the benevolent decision to allow Ukrainian agricultural exports to enter Europe is another recurring gripe among farmers.