It's been over a week since B.C. wildfire smoke started blanketing Metro Vancouver, and the skies remain hazy and grey.

But there does appear to be an end in sight: officials are hopeful the smoke will finally start to subside Thursday evening and continue to clear away through the weekend. 

In the meantime, here are some answers to the most common air quality questions, courtesy of Dr. Sarah Henderson, senior environmental health scientist at the B.C. Centre for Disease Control.

Should I wear a mask to protect myself from harm?

"If you're wearing a surgical mask, it's not doing anything for you," Henderson says. "They're not designed to filter out these fine particles."

The only type of mask designed for these particles is the N95 respirator, and even those must be properly fitted to your face to be effective.

"Then once it is properly fitted to your face it makes it hard to breathe so if you're having a hard time breathing in the first place it's not necessarily the best idea. We do recommend them for people who have to work outdoors for long hours," Henderson says.

So what can I do to avoid the smoke?

"Seek better air somewhere. Indoor environments can be better than the outdoor environment, depending on the air coming in. Generally places like shopping malls, community centres, libraries, they have big ventilation systems with filters on them so it's nice and cool and clean in those environments," Henderson says.

At home, people can also use an air cleaner to keep the air fresh in one room.

Does shutting my windows help keep the smoke out?

"Having your windows open is going to let more smoke in," Henderson says, but that doesn't necessarily mean the fine particles aren't getting into your home.

"The indoor infiltration of outdoor air is a complex science and it really depends on a) whether or not your windows are open, and b) how your home is built," Henderson says. "If you live in one of these older Vancouver homes with wooden siding and not a lot of insulation, they're pretty leaky so the outdoor air comes indoors quite quickly – and certainly having your windows open will just make that even quicker."

Some newer homes that were built under more restrictive building codes have less outdoor air infiltration, however.

Are there any long term effects to breathing this air?

The short answer is: probably not, but like the skies on the South Coast, it's not totally clear.

"It's irritating in the short term, the chances of any long term effects are very low but it's not something that's been well-studied," Henderson says. "To do a study like that you'd have to find a population that was exposed to an event like this and then you'd have to follow them for 20 years. You don't get that opportunity very often."

With files from CTV Vancouver's Shannon Paterson