ADVERTISEMENT People exposed to higher levels of air pollution appear more likely to develop a type of brain tumour that does not typically cause cancer but can lead to other health issues, a new study has found. Meningiomas are the most common type of primary brain tumour, and grow slowly enough that it can take years before they are detected. They originate in membranes that surround the brain and spinal cord. Only rarely are they cancerous, but meningiomas can cause other disabilities by