Canadian wildfire smoke in the Lehigh Valley: How to protect indoor air

BETHLEHEM, Pa. — From an invisible, radioactive gas that has no smell or taste, to particles too small to be seen with the naked eye, Lehigh Valley residents face a handful of different indoor air quality threats.

“Radon gas exposure is the second leading cause of lung cancer after smoking; it seeps into homes through cracks in the foundation where it can be unknowingly inhaled,” said Chrysan Cronin, associate professor and director of public health at Muhlenberg College. “ … There are other invisible pollutants in your home such as volatile organic compounds (VOCs) that offgas from paint or carpeting that would need special monitors to detect.”And then, there’s PM2.5 — the fine particles in wildfire smoke that can make it deep into a person’s lungs.

Air quality has been a point of concern across the Valley after wildfire smoke in early June blew in from Canada, giving the region some of the worst air outdoor quality in the nation. While the smoke, which can seep into older or drafty homes, is only the latest threat, experts and professionals said there are ways to monitor and improve the indoor air residents are breathing.

Bob Burkholder, owner of Burkholder's HVAC in Emmaus, said he didn’t believe the company has seen much of an impact from the Canadian wildfire smoke, but air quality has been a growing concern.

“Air quality has definitely become a larger focus for our customers in recent years,” Burkholder said. “We've seen a dramatic increase in the installation of UV lighting as well as HEPA filtration in many of our customers' homes to help improve indoor air quality.”

UV lamps “may destroy biological pollutants such as viruses, bacteria, allergens and molds that are airborne or growing on HVAC surfaces (e.g., found on cooling coils, drain pans, or ductwork),” according to the U.S. Environmental Protection Agency. “If used, they should be applied with, but not as a replacement for, filtration systems.”

Filters designated HEPA, or high-efficiency particulate air, theoretically remove at least 99.97% of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 microns, according to the agency.

“True HEPA filters are normally not installed in residential HVAC systems; installation of a HEPA filter in an existing HVAC system would probably require professional modification of the system,” according to the EPA. “A typical residential air handling unit and the associated ductwork would not be able to accommodate such filters because of their physical dimensions and increase in airflow resistance.”

Air quality can be negatively impacted by a number of pollutants, but there are ways residents can monitor it, Burkholder said.

“One of the simplest ways of knowing if you have air quality issues within your home is if you have allergies,” Burkholder said. “If your allergy symptoms don't subside while in your home, it is very likely you have air quality issues.”

While there are monitors available for sale online and in stores, it’s best to consult a trained HVAC professional before deciding on an air monitoring system, he said, as different devices monitor for different types of pollution.

The air quality can also differ throughout a home.

“For example, with radon, since it seeps in through the foundation of the house, the basement/lower floors are most likely to have higher levels,” Cronin said. “This may not be true for other indoor air pollutants where the levels may be the same in every room.

“The best thing to do is to monitor the air in the room where you spend the most time. If the air quality is good there, then it's likely to be good in the rest of the house.”

For those residents without HVAC systems, improving air can be trickier.

Window air conditioners bring in air from the outside and don't have any filtering capacity, Cronin said. However, air purifiers can be very effective in clearing the air of small particles such as viruses and PM 2.5 depending on the size of the air filter being used.

When smoke inundated the Valley in June, air purifiers were in high demand and short supply. Since then, stock seems to have rebounded.

The EPA recommends a high-efficiency portable air cleaner for wildfire smoke.

“How well they reduce air particle concentrations depends on several factors, such as the size of the air cleaner, the area to be cleaned, the filter efficiency, how frequently the unit is turned on and the fan speed,” according to the agency. “Portable air cleaners fitted with high-efficiency filters can reduce indoor particle concentrations by as much as 85%.

“Furthermore, portables can be operated continuously at a lower cost compared to the continuous operation of a central system.”

While radon test kits are relatively inexpensive, air monitors and purifiers can cost hundreds of dollars. However, paying attention to what the air quality is like outside will provide a good indicator of what may be happening inside, Cronin said.

If the air quality outside is poor, and a resident is in a vulnerable group or if they are just bothered by the air that day, they might consider wearing a mask indoors.

“An N95 or KN95 mask would be very helpful in filtering out the PM 2.5 that comes from smoke inside,” she said.

Residents can also make a DIY purifier by securing a 20-inch by 20-inch air filter to the same size box fan, according to the EPA.

Cronin said they have been popular since their inception during the COVID-19 pandemic and “are actually really, really good at filtering out PM 2.5 and small particles such as viruses.”

There can be drawbacks to using a DIY air cleaner, like increased noise and heat generation from the fan motor, and there’s still limited data on how well they filter smoke particles.

“When commercial air cleaners are not available or affordable, DIY air cleaners may offer some protection from smoke indoors,” according to the EPA. “It is also important to take other steps to reduce your exposure to particles during wildfires, and to keep an eye on temperature and make sure you have a way to stay cool, even if that means going somewhere else.”