Can I use just any sand for blasting?

No, abrasives which contain more than 1% free silica are forbidden.

In the past, blast cleaning operations were done with silica sand. The term sandblasting originates from those days. Nowadays, it's clear that exposure to respirable crystalline silica during sandblasting can cause a serious or even fatal respiratory disease, called Silicosis, a scarring and hardening of the lungs.
In most countries, it is now forbidden to use abrasives which contain more than 1% free silica. Silica sand contains 90% or more! During blasting the sand particles break down into very small particles. These particles, smaller than 5 microns, are inhaled and become embedded in the lung, causing respiratory problems, pulmonary silicosis (also called 'dust-lungs'), and eventually even death.

It is assumed that a blasting helmet provides enough protection but this is not true. When blasting with silica sand, large clouds of dust will arise in the surrounding air. A crystalline silica dust particle of 2 microns drops only 1 metre per 24 hours, during windless conditions! This means that the dust-clouds remain invisibly in the air for a long time, long after the sandblasting is finished. When the blaster stops and takes off the blast helmet, a large quantity silica dust will be deposited inside the helmet. When he puts the helmet back on, he will inhale an extreme dose of free silica dust instead of getting the protection he expects.
The risks for people in the vicinity are even higher. Think of other workers on site. The dust-clouds are spread-out by the wind and these people do not have any protection at all.

During the past years, most countries have established laws to prohibit the use of sand  for blasting. In the Netherlands, sandblasting with silica sand has been forbidden already since 1957 and instead of "sandblasting" we now speak about grit or shot blasting, abrasive blasting or blast cleaning.
High quality substitutes are widely available: Aluminium Silicate (coal slag grit), Glass Granulates, Olivine and Garnet. All these abrasives contain far less than 1% free silica making them worldwide approved abrasives.