Leaky ducts will obviously be less efficient plus will likely pull in unhealthy air, such as dust, mold and other polutants. This could also lead to poor humidity control which will help that mold spread. If the static pressures are off, you could be dealing with a number of issues including your system could be producing carbon monoxide. Additionally with an airflow pressure problem, your AC blower could be working too hard to pull in the return air, in effect wasting energy causing your electric bill to rise. We can inspect and if required protect your indoor air quality with proper air duct sealing.