The fierce wildfires that broke out across much of the western United States this summer, spreading smoke across hundreds of miles, continue to pose a serious health hazard to millions.

Right: https://www.airnow.gov/wildfire-smoke-guide-publications/

More are expected this fall. That’s a major health concern because microscopic particles in wildfire smoke, carried by the wind, can penetrate deep into your lungs and travel into your bloodstream. One study linked wildfire smoke exposure to a twofold increase in the rate of asthma and a 40% rise in strokes and heart attacks. Other research tied smoke to hospital admissions, ER visits and premature deaths.

The standard advice is to stay inside when heavy smoke is in the air. But the smoke can get into your house or apartment. So you might want to consider investing in equipment to clean the air inside your home, especially with climate change likely to continue escalating the scope and intensity of the fires.

“I think we have fires enough now that people should think of this as something they want to buy,” says Deborah Bennett, a professor of public health at the University of California-Davis. “Even if they only turn it on during the fires, there’s going to be plenty of times when they’re going to have it turned on.”

There are many options for cleaning the air in your home, depending on your circumstances and — of course — your budget.

If you have an HVAC system, it likely recirculates air that’s inside the house rather than drawing in air from outside. But if you have an air conditioner with a “fresh air” system that brings in outside air, you should turn off the fresh air setting on heavy smoke days. If you don’t know how, seek professional advice.

And be sure to close all doors and windows; otherwise, your efforts will be in vain.

You can convert your HVAC unit or furnace into a better air-cleaning system by installing a higher-efficiency filter capable of catching a large proportion — though it won’t get 100% — of the tiny smoke particles.

To cope with wildfire smoke, many public health and air quality experts recommend what’s known as a MERV 13 filter. MERV, or “minimum efficiency reporting value,” is a scale from 1 to 20 that rates a filter’s ability to capture particles. MERV 1 is the lowest rating, indicating the least impact on air quality, while filters rated MERV 17 or higher are used in hospital operating rooms and clean rooms.

You can buy MERV 13 filters at large stores such as Costco, the Home Depot and Lowe’s or online from multiple vendors. A MERV 13 should cost around $20, or substantially less if you buy packages of them.

Before you install a new filter, check first with an HVAC professional to make sure your system can accommodate it. The more efficient the filter, the more it reduces airflow, diminishing the cooling capacity of an air conditioner and requiring more energy to run the heater.