They have a huge impact on the local economy, damage the environment and destroy property.
People can be seriously injured, and in the very worst of cases, deliberate fires can result in someone's life being taken.
They also take up a huge amount of time for our hardworking firefighters.
This has been acutely felt this year due to the Covid outbreak, which has seen fire services giving up staff to help deliver food and medicine to vulnerable people.
Firefighters have also supported police and ambulance services dealing with the pandemic, and let's not forget, they also have the day job to contend with.
With this in mind, it is hugely disappointing that across our region there were more than 1,600 blazes started deliberately in the first three months of the national lockdown.
While this represents a fall on the same period in the previous year, it piled extra strain on fire services at a time when manpower was already stretched to its limits.
Attending a deliberate fire is time away from attending other life-threatening incidents and carrying out other vital work.
To be clear, the majority of deliberate fires are not considered arson, which is a specific criminal act against property.
They also include bonfires, grass fires and rubbish fires, which are often started by people who have not considered the consequences of their actions.
Nobody needs reminding that the coronavirus pandemic is still very much alive.
Quite simply, by reducing the number of preventable fires, our fire services will have more capacity to support the most vulnerable people in their communities, while also maintaining their ability to respond to genuine emergencies.
As a country, we have come together remarkably well during the pandemic. People have gone out of their way to support others around them.
But particularly in these trying times, we need to protect our emergency services and ensure their precious time is not wasted.
Those who refuse to comply deserve to feel the full force of the law.