Staying Inside Won’t Protect You from Smoke Unless the Air is Clean
Officials encouraged New Yorkers to stay home, but there’s no guarantee the air inside is clean. Here’s a guide on keeping your indoor air as pollution-free as possible — including how to build a filter with a box fan.
As New York City’s air quality remained unhealthy due to Canadian wildfires, Mayor Eric Adams encouraged New Yorkers to avoid going outside to protect themselves from the pollution.
The city made it easier for some New Yorkers to stay home, including allowing remote instruction for public school students, halting eviction proceedings on Thursday and suspending alternate side parking on Friday.
But the advice to stay home isn’t enough without attention paid to the quality of the air indoors, experts told THE CITY.
Montana, a state much experienced with dealing with wildfire smoke, has learned that lesson.
During smoky periods, Sarah Coefield, air quality specialist at the Missoula County Health Department, was for years mainly responsible for telling people to stay inside. But then her team “really learned how much smoke comes inside,” she said.
“At that point, just telling people to go inside isn’t sufficient. We need to actually clean the air inside these buildings,” she said.
Now, she makes sure to explain actionable steps individuals can take to improve the air quality in their homes, which New Yorkers can apply to their apartments. (Of course, the situation is more complex for unhoused New Yorkers.)
Here’s what you can do to keep things as clean as possible inside:
Smoke contains fine particulate matter, a microscopic form of pollution that can be inhaled, enter the bloodstream and damage the vital organs. Exposure to it can worsen heart and lung diseases and put children, the elderly and pregnant people most at risk. It can also trigger headaches, shortness of breath and fatigue in healthy people.
Indoors, keeping the smoke at bay — and monitoring it — is a key way to protect health.
Dr. Mary Prunicki, director of air pollution and health research at Stanford University’s Sean N. Parker Center for Allergy and Asthma Research, recommended air monitors to keep tabs. She has multiple devices in her home, which detect everything from cookinge to hair products.
“Sometimes the air quality inside can be just as bad or even worse than that outside,” she said.
“I would say awareness is the first step,” she added. “I know just anecdotally when I turned on my stove, that my monitor on the other side of the room went off. I have a monitor in my daughter’s room and I knew when she was using hairspray — it would spike.”
Once you know what’s causing air quality to drop, do everything you can to stop it from entering your air in the first place, experts say.
“It’s much easier to remove the pollution source than to try to mitigate it, or modify it, or filter it,” said Drew Michanowicz, a senior scientist with the nonprofit PSE Healthy Energy.
Keep doors and windows closed to prevent smoke from getting inside. You can stuff rags, towels or sheets to block air coming from the sides of windows or bottom of doors. If you must vacuum, do so with a HEPA filter or opt to dust with a damp cloth or mop to avoid kicking up particles.
Avoid cooking with gas stoves, as burning methane indoors releases the pollutants nitrogen dioxide and carbon monoxide, which are harmful to health. Instead, you should aim to prepare food with a microwave, induction cooktop or slow cooker.
And if it’s not feasible to make the air in your whole apartment clean, compartmentalize.
You can create a designated clean air room, using guidelines from the Bay Area Air Quality Management District — which regulates pollution in that part of northern California. Pick one room in your home, seal the doors and windows to prevent leakage, run an air purifier, avoid smoke-creating activities (like smoking or cooking) and make sure you have high-quality filtration (more on that below).
Lindsay Robbins, who works on building efficiency and decarbonization for the Natural Resources Defense Council, pointed out the importance of comprehensively retrofitting buildings with an eye towards climate and comfort.
“Most New Yorkers still live in inefficient, leaky buildings with windows as the only option for ventilation,” Robbins said. “We need to get under-resourced buildings the resources they need to do comprehensive retrofits that will truly make their homes safe, healthy and affordable places to live.”
Funding from the federal Inflation Reduction Act and other utility-run rebate programs, she said, could help certain property owners finance these upgrades, such as replacing fossil fuel-powered appliances with electric ones, insulating and air sealing and installing ventilation systems.
Filter Dirty Air
Even with the best efforts, some smoke will likely make its way inside. When it does, there are several options to clean the indoor air, depending on your home and means.
If you have central air or a central HVAC system, investing in a high-quality air filter is critical. Coefield of Missoula recommends getting a filter rated as MERV 13, which denotes how effective the filter is at removing certain-sized particles from air. (Prices for MERV 13 filters range from approximately $40 to well over $150.)
Coefield also said to make sure to decouple the fan from the thermostat, so that you have the option to run your system — and therefore clean the air — without changing the temperature, as some systems shut off the fan when the desired temperature is reached.
“You cannot assume that because the place is air conditioned, it has clean air, because those are two different functions of your HVAC system,” Coefield warned.
If you don’t have central air or an HVAC system, you can use a portable air cleaner with a HEPA filter in it, which can cost around $100. Coefield cautioned that you should make sure the air purifier is appropriately sized for the room that it’s to be used in, taking into account ceiling height. You’ll eventually have to replace the filter, but most HEPA filters can easily handle week’s worth of smoke, Coefield said.
It’s also easy and efficient to make your own air cleaner using a box fan — ideally manufactured after 2012, for fire safety reasons — and a furnace filter, she said.
Taping the filter to the fan makes an air cleaner “that’s good for a room that’s about 200 square feet,” Coefield said. According to her guide on the do-it-yourself box fan filter, the total cost is about $40.
The way the air purifiers are most effective is if they run continuously, so keep the fan, HVAC system or air purifier running.
“If you keep your doors and windows closed and just continuously move the air in your home through that filter, you can clean the air pretty quickly,” Coefield said.
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