Experts on Camera

Dr. Nathan Phillips: Health and environmental impacts of natural gas appliances

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Residential natural gas use contributes to greenhouse gas leaks and reduces air quality in homes. Some jurisdictions have restricted gas in new construction, while twenty states have pre-emptively banned restrictions on gas in new construction.

On Wednesday, August 31, SciLine interviewed: Dr. Nathan Phillips, a professor in the earth and environment department at Boston University. See the footage and transcript from the interview below, or select ‘Contents’ on the left to skip to specific questions.

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NATHAN PHILLIPS: My name is Nathan Phillips. I’m a professor at Boston University. I’m an ecologist, and so I study trees and forests and how they respond to climate change. And that’s actually how I got into studying natural gas systems—because leaking natural gas kills trees—and so my entry into the area of gas, natural gas systems, was as a tree physiologist and an ecologist.


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What is natural gas?


NATHAN PHILLIPS: Natural gas is mostly methane, between 90 to 97.5% methane. I just checked it last night in terms of the systems that supply in the Boston area, where I am. And then there’s other hydrocarbons in there, like ethane and others. And then there’s very minor constituents which are volatile organic compounds, sulfuric compounds, and these compounds are there in minute amounts, but they’re not good for human health, and in many cases, there’s no determined safe lower level for these compounds, like benzene, toluene, xylene, hydrogen sulfide. And so, yeah, these are compounds we need to be very careful about, indoors and outdoors.

How do natural gas emissions from home appliances affect people’s health?


NATHAN PHILLIPS: Let’s start with what’s supposed to happen with gas that comes into homes and buildings, which is that it’s intended to be burned, to be combusted. And what happens when combustion happens, for example, in a stove, a gas stove, is that there are combustion emissions that come off of that, including oxides of nitrogen—people call that NOx—and soot or black carbon. And these are unhealthy for respiratory health on short terms and chronic if longer exposure exists. So, these are triggers of asthma and other respiratory conditions.

There’s also the possibility of gas leaking into homes, either from basement boilers or incomplete combustion in stoves. And that’s where those little microcompounds become very important—the benzene, the toluene, the xylene, the hydrogen sulfide. And those things have a lot of different health impacts, including being carcinogenic, neurotoxic and having other respiratory impacts.

How does natural gas affect the environment?


NATHAN PHILLIPS: Leaks of natural gas, whether it’s inside a house or out on the street and sidewalk, has issues that go from the point of the leak all the way up to the planet. And so, we can start at the point of the leak. When the gas leaks into soils, it will damage street trees because the tree roots need oxygen, and that gas leak displaces the oxygen and damages and kills street trees or street trees in a yard.

And then as you go up in scale, at the scale of the community, there are—the air quality degrades because of the gas leak. So, mostly methane is coming out, and that methane participates in photochemistry, which leads to ground-level ozone production. And ozone at the ground level is bad for our lungs. It’s bad for every living tissue, basically, plants or animals. And so, that’s kind of the community scale.

And then when we go up to the largest scale, we’re talking about climate change. So, methane—again, 90 to 95% of the gas is like a greenhouse gas on steroids. It’s dozens of times more powerful than carbon dioxide is. So, it’s a big climate problem. And then there’s the money problem, meaning ratepayers are generally paying for the lost gas. And in Massachusetts, where I live, that amounted to about $90 million a year in lost value every year from leaking gas.

And I think I forgot also to mention, at the point of the leak, going all the way back to that scale, there’s the safety issue. So, these leaks can be hazardous. If they build up to about 5% gas in a confined space, then it becomes a safety hazard, an explosion risk.

How widespread are unrepaired leaks in outdoor gas lines?


NATHAN PHILLIPS: We know that this problem is widespread across the Eastern Seaboard from Washington, D.C., all the way up to Boston and beyond. That entire—which is the biggest kind of megalopolis on the continent of North America. And that’s because this is the oldest part of the built infrastructure. So, we have gas lines from Washington, D.C., to Boston that go back a hundred years or more. And so, they’re leaking. It’s widespread. Multiple independent studies from the sidewalk and street level, all the way up to using aircraft and satellite, have shown that this problem is widespread across the Eastern Seaboard. It’s also a problem out in other parts of this country and around the world. Even if there’s new infrastructure, new pipelines, there can be big leaks, catastrophic leaks in some cases. We’ve seen it out in California and elsewhere.

What do you think of the new federal tax incentives for electric appliances?


NATHAN PHILLIPS: The federal incentives that have just been written into law couldn’t have come at a better time because we have the tools now to make the transition we need to cleaner, safer ways to heat our homes and cook our food using electricity. And so those tools are in place, and yet they need to be moving faster. They need to be scaling faster. So, for example, heat pumps in homes that can very efficiently and safely heat and cool our homes are there, but the adoption rate is not as fast as it needs to go. So, these incentives will really, really help speed that market along and start to feed on itself and start scaling rapidly.

What’s your advice for homeowners thinking of switching from gas to electric appliances?


NATHAN PHILLIPS: Plan for the future. If your boiler—your old gas boiler—is getting old, don’t wait to make a decision after it breaks down because if you’re in that situation, you’re going to have to just be reactive. Come up with a plan beforehand as to what you want to do to upgrade your system to a safer, cleaner electrical-based system, whether that be your HVAC system, replacing air conditioners and heaters with air-source heat pumps, for example, that extract heat from the air outside the home, or whether it be a hot water heat pump in your basement that replaces the old gas-fired water tank. So, have a plan ahead of time, and learn about those federal incentives. That’s going to make it a lot more affordable.

Are there states or cities that are implementing programs to build on the new federal incentives?


NATHAN PHILLIPS: There’s a variety of I would call them “carrots and sticks” types of policies that are in place. And so, in some towns like—or states, like Massachusetts, has just passed an electrification law that allows communities to require new construction to be electrically based, electric-based heating. So, it’s a step in the direction of the transition off of gas to electrification. And then there’s other incentives that communities are offering for—everything from solar panels, community solar to heat pumps, state programs, municipal programs that are all adding to those—the federal law.

How are reporters doing covering natural gas appliances?

(Posted August 31, 2022 | Download video)