Our mission to help you navigate the new normal is fueled by subscribers. To enjoy unlimited access to our journalism, subscribe today.
They have killed dozens of Americans and destroyed hundreds of homes, but the biggest threat of the wildfires raging on the U.S. West Coast may be invisible. The tiny airborne particles of ash and chemicals generated by the fires can travel hundreds or even thousands of miles, and can cause not only short-term symptoms like flareups of asthma or watery eyes, but serious longterm cardiovascular damage that increases the risk of death for potentially millions of people.
The guidelines for staying healthy while big fires burn has long been simple: stay inside and, when possible, use air filters to capture those dangerous microparticles. But the coronavirus pandemic has caused shortages of key air-quality supplies, and is forcing some difficult tradeoffs on indoor air safety.
Both fine smoke particles and the coronavirus can be captured by a class of air filters known as MERV-13, which can be installed in many existing heating and air conditioning systems. But because these filters weren’t in wide use before the pandemic, a sudden surge in demand has created ongoing MERV-13 shortages.
Mike Gallagher, president of HVAC contractor Western Allied, believes that’s going to catch commercial building managers by surprise once the current wave of fires dies down.
“Once the smoke clears, it smells okay outside, but you walk into the building and it smells like smoke. That’s when they realize they need new filters,” says Gallagher. But with waiting lists for MERV-13 filters as long as two months, Gallagher expects many buildings in smoke-affected areas will be forced to temporarily resort to MERV-8 filters, which are not capable of clearing the coronavirus from the air. That could increase the infection risk in shared spaces including offices, restaurants, and movie theaters.
The coronavirus is forcing a second difficult choice as the fires rage: whether to let in outside air to reduce the risk of infections, or seal buildings up tight to keep out smoke particles.
“For [protection against] COVID, you want to get the [outside air] ventilation rate as high as possible,” says HVAC veteran Tom Javins. “But with wildfire smoke, you want to have the ventilation rate as low as possible. Because the pollutant is in the outside air, not the inside air.”
Javins sits on a committee of the American Society of Heating Refrigerating, and Air-conditioning Engineers (ASHRAE), which is developing best practices for heating and ventilation under wildfire conditions. Though the double-bind of the coronavirus and smoke is challenging, his bigger concern is widespread indifference: “Most [commercial] building managers don’t do anything” to adjust for dangerous outside air quality, he says, and he frequently finds that the vents controlling outside air flow for big buildings have broken down entirely. Most often these vents, known as air dampers, are stuck closed, helping …read more