In every lease their is an implied right to "quiet enjoyment". This means that a tenant has the right to the peaceful and undisturbed use of the rental premises. In your case, due to the expansion of the adjacent business (assumably without your knowledge prior to your taking occupancy), this right has been breached. In such a situation a tenant basically has 2 options: withhold rent until the condition ceases (from action taken by either the tenant or the landlord) or terminate the lease. Under your specific set of facts the first option appears neither reasonable nor likely. However, ending your lease and vacating the premises does. In such an event, you could hold your landlord liable for reimbursement of any expenses incurred as a result of a move.Note: Before undertaking any such remedy you need to consult with an attorney who specializes in these matters or at least speak with a tenant's rights advocacy group. Not following the correct legal steps for a lease termination can result in liability for you.