I took a look and see a few (dime-sized and smaller) gray colored areas which may be mold. However, I am not sure how the 'mold' would come inside and impact her inside the house. I realize the windows are older and the sealing of the double-pane may be compromised, but not sure this can be addressed. Based on my understanding, the windows would not be easily cleaned between the panes, but need to be replaced. Any other suggestions? --12.151.xxx.xxx

This is why I like m2m leases. Don’t feel safe living there? Buh bye. --50.219.xxx.xxx

What has to be done is the double pane seal is broken where the entire pane must be replaced. It maybe one window or multiple windows. The mildew between the pane does not effect the building or house. If multiple panes require replacement will the tenant be wiling to pay a higher rent. --68.69.xxx.xxx

Equally I have had former smokers complain that something like this is hurting there lungs too. You should act on this, but let the residents know that ordering and getting replacement glass will take a few weeks. --24.101.xxx.xxx

If they are from Window World they may be free or very inexpensive to have changed out. Otherwise, regarding the situation I would just monitor and do worry, put this on your list to check when you change the furnace filter or regularly inspect. --172.59.xxx.xx

Sounds like the beginning of the end. --24.183.xxx.xxx

And there are millions of species of mold in the world, and only a few are actually harmful to humans. Go to the EPA and search on Mold. --50.82.xxx.xxx

About 5% of people are allergic to mold, causing symptoms like those you described, but it's very unlikely that mold between panes is causing their problem. --107.141.xx.xxx

Call around your better hardware stores that can do double pane windows, reworking the window is about 25bux, they cut open and replace the rubber seal - of course they wash the glass before resetting in your sash. If this person has ever gone outside they have had more mold exposure than one could get exposed to indoor mildew, lousy housekeeping results in mildew becoming mold. --76.190.xxx.xxx

My local glass company replaces the glass for me all the time. I have old triple track aluminum windows and am not ready to replace window for the building. When the glass seal is gone and they are fogging up, etc they measure and replace for me. It can take weeks or months for the glass to come in since supply chain/pandemic issues. Once the glass arrives, they come to the building and each window takes them about 5 min to replace. Over the course of the 10 years we have owned the building, I think most windows have been done at this point. --75.67.xxx.xxx