To answer the above question we first should understand what exactly are radio waves?
ChatGPT says:-
Radio waves are a type of electromagnetic radiation with a specific range of frequencies that are used for communication, broadcasting, and many other applications. They are a form of energy that travels through space at the speed of light, just like visible light, X-rays, and other forms of electromagnetic radiation.
Radio waves have a much longer wavelength and lower frequency than visible light. The range of frequencies typically referred to as radio waves spans from a few kilohertz (kHz) to many gigahertz (GHz). The lower frequencies are used for long-range communication, such as AM radio broadcasting, while higher frequencies are used for short-range communication, such as Wi-Fi and Bluetooth like in earbuds.

Radio waves are generated by a transmitter and travel through space until they reach a receiver. They can be transmitted over long distances without the need for wires or cables, making them ideal for communication over large areas. Radio waves can also be reflected, refracted, or diffracted by various materials, which can affect their propagation and allow them to be used for specific purposes, such as radar and remote sensing.
In summary, radio waves are a type of electromagnetic radiation used for communication and many other applications, with a specific range of frequencies that travel through space at the speed of light.
So now we know what exactly they are and now we also can understand as to why they loose strength in signal when traveling over distances. Furthermore this effect is known as the inverse square law which states that the power of a signal decreases with the square of the distance from the source. Another thing to keep in mind is that radio waves can also be absorbed or scattered by various materials in their path, such as buildings, trees, and even the Earth’s atmosphere. As a result, the strength of a radio signal decreases over distance, and at some point, it becomes too weak to be detected by a receiver.

For Radio waves to cause pollution they need to accumulate however their physical characteristics ensure that they diminish rather quickly all things considered and as a result are non polluting in nature and theory.
But that does not mean they are not harmful. High level of exposure even for short bursts which includes radio waves, can lead to tissue heating and damage, particularly in the skin and eyes. This can occur when a person is exposed to a high level of RF radiation for an extended period or when exposed to a very high level of RF radiation for a short period.
Furthermore, some studies suggest that long-term exposure to low levels of RF radiation (maybe even Wi Fi) could potentially have harmful effects on biological systems, such as changes to gene expression, immune function, and cell growth. However, the scientific consensus is that there is currently no conclusive evidence that exposure to low-level RF radiation has harmful effects on human health.
Therefore, while strong bursts of radio waves can potentially affect organic life, the effects are typically dependent on the level and duration of exposure. Regulators and authorities enforce guidelines to limit exposure to radio waves to safe levels to prevent potential harm to human health.