When Hurricane Sandy swept through the Northeast, it flooded tens of thousands of homes.  If you had water in your home for at least two days, chances are some mold colonies are growing, according to the Federal Emergency Management Agency.  Here’s what you may not realize: mold may not be visible immediately, but its spores are growing.

Here’s what you need to know about mold:

What is the health impact of mold?

Mold can cause a host of health issues. It has been known to trigger allergies that cause headaches and coughing, as well as irritate the nose, skin, and eyes. For people with asthma, mold can make breathing particularly difficult. The Huffington Post recently discussed in depth the health risks of mold.

Who should test for mold and when?

Consumers should have a certified professional test for mold, but he should not perform remediation services so as to avoid any conflict of interest.  The professional (a certified microbial inspector) will discover mold’s root causes and provide a detailed report with recommendations on how to remove the mold.  You should test for mold before you hire a remediation company, and again after work is complete to make sure the mold has been properly removed and will not grow back and resurface a few months later.

How much it will cost? Who is going to pay for it?

Mold testing starts at a few hundred dollars, and removal costs can run the gamut, from $200 for smaller removal jobs up to $30,000 for homes that have been flooded, said the Huffington Post. Unfortunately, mold remediation is generally not covered by most home insurance policies, according to FOX Business. While flooding caused by an unforeseen pipe burst will generally be covered under most homeowner policies, mold claims arising from storm flooding must be handled under a separate rider to your policy, according to Marshall McKnight, a spokesman for the New Jersey Department of Banking and Insurance. The costs vary according to the home’s location and the individual insurer, but $50,000 in protection will probably cost you an extra $47 a year, said Bill Wilson, a spokesperson for the Independent Insurance Agents & Brokers of America.

But whatever you do, remember to hire an independent testing company that does not also do remediation. That way, you will be assured that you are not paying for something you might not need.