It's Time to Get Serious About Particulate Pollution

Everyone has so studiously ignored it for so long, but organizations are demanding action.

Corner of Liberty and Fifth Avenues
"Corner of Liberty and Fifth Avenues" from the Smoke Control Lantern Slide Collection.

Smoke Control Lantern Slide Collection, ca. 1940s-1950s / University of Pittsburgh

Nobody used to talk much about particulates. Like these guys having a smoke at noon in Pittsburgh in 1940, everyone was swimming in a soup of particulates from cars, from burning coal for industry as they did in Pittsburgh, and of course, from smoking. It was a given in our lives.

As Treehugger's Russell McLendon noted:

"People have been choking on manmade air pollution for roughly half a million years, ever since Pleistocene cavemen huddled around the first campfires. That was clearly worth a few lungfuls of soot — fire gave us warmth, night vision and cooked meat, most likely outweighing the times it gave us bronchitis."

Nobody regulated them either. It wasn't until 1997 that the EPA even recognized particulate matter smaller than 2.5 microns (PM2.5) as a hazard and set a standard of 15 micrograms per cubic meter (μg/m3) based on a three-year average for outdoor air. It's a standard that has gone up and down ever since due to court challenges and has sat at 12 μg/m3 since 2013.

Particulate regulation is supposed to be changing under the current administration, but they missed a November 14 deadline by which they were supposed to have reviewed new standards. The Center for American Progress is calling for lower levels (8 micrograms per cubic meter annually and 25 micrograms per cubic meter daily).

So does the Climate Action Campaign, where 167 organizations signed a letter to the president that read: "Each day that passes without updated limits is another day that millions of Americans are exposed to unhealthy and potentially deadly levels of soot pollution. Additionally, the delay in pushing forward a strong soot pollution standard is also holding back the co-benefits we would see for nature and our ecosystems as well as in reductions in other air and climate pollution."

They conclude:

"We urge you to move quickly to advance and finalize stronger soot pollution standards and to swiftly move all rules forward that protect public health, stave off the worst of the climate crisis, and improve the quality of our lives. Every additional day of delay means hazy skies and more toxic soot pollution in the lungs of our vulnerable children and seniors."

“We know the science is better and we know the technology is better,” Margie Alt of the Climate Action Campaign said in an interview, reports Inside Climate News. “We know that exposure to soot leads to increased mortality, leads to more hospitalizations and more visits to the emergency room. Asthma is the most obvious disease that’s triggered by it, but it can also trigger heart attacks and strokes and Parkinson’s and COPD”—chronic obstructive pulmonary disease—“and risk for preterm births and infant mortality.”

What about indoor air quality?

EPA indoor air quality


None of these organizations' demanding tougher standards mention regulating indoor particulate pollution, even though the EPA says, "Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations."

The EPA has never set standards for indoor air. The EPA rarely even mentioned particulates in our homes until November 2, 2022, when they updated a page on their website, Sources of indoor particulate matter (PM). This is a fascinating document, as much for what it leaves out as what it includes.

The first thing they note is that PM from outdoor air is a major source of indoor PM: "Outdoor PM can come in through open doors and windows. It can also come in through small cracks and crevices." This is a major argument against the "a house needs to breathe" crowd because it is breathing in PM and other pollutants.

The EPA then lists the major interior sources of PM, including:

Cooking, where they recommend using a range hood every time you cook, preferably one vented to the outdoors rather than recirculating, and "choose a range hood with the appropriate airflow for your home." The EPA points to a document with good advice for hoods, including "Avoid the low profile, “designer” type hoods." This is good news; we have called the kitchen exhaust fan the most screwed up, badly designed, inappropriately used appliance in your home.

Combustion and heating, where they tell us not to allow smoking indoors and "avoid the use of unvented combustion appliances indoors. This includes stoves, fireplaces, or fuel-powered space heaters."

The EPA continues with other sources of PM, including indoor dust that might carry plastics, flame retardants, and other chemicals; biological contaminants like pollen and dust mites; consumer products like air fresheners; and finally, one that we have complained about for years only to have people look at us funny: printers and copiers.

"Some equipment, such as some copiers, laser-jet printers, and 3D printers can generate PM directly. Printers and copiers can also generate other harmful pollutants such as volatile organic compounds (VOCs). VOCs can then react with other chemicals in the air or on surfaces to form more PM."

But there is so much left unsaid in this list. They tell us to avoid unvented combustion appliances, including stoves, but never say no to gas stoves in the kitchen, even though there is lots of research concluding that they are harmful. They never mention choices of finishes, such as carpeting, that can hold lots of PM, or of furnishings, which can hold many pounds of flame retardants. They do not come out against burning wood. They call for upgrading furnace filters and using portable air cleaners but do not suggest buying a good monitor so that you know what levels of pollution you have in your home. And most importantly, they never mention a standard, a number that they consider safe.

Perhaps a look at the list of organizations that protested any change to the PM standards during the last administration will tell us why the EPA has made such wimpy recommendations. The last time around, they heard objections from the car makers, the petrochemical manufacturers, the petroleum institute, the cement associations, and the wood industry. All of these industries generate PM, and they are in and around our homes. When you regulate PM2.5, you are regulating fossil fuels, and we can't have that.

Indoor Air quality

Government of Canada

With all the calls for tighter standards for outdoor PM regulation, perhaps it is a good time to look at a standard for indoors. The Canadian government did, but do not appear to have set a firm standard. Health Canada wrote 10 years ago: "With respect to indoor PM2.5, Health Canada is not proposing a specific maximum exposure limit, but is recommending that indoor PM2.5, at a minimum, be lower than PM2.5 outside the home. Having an indoor level that is greater than the outdoor level indicates a strong indoor source(s) of PM2.5 that needs to be addressed."

Air quality inside
Awair Monitor reading November 22.

Lloyd Alter

So we are on our own here. My suggestion might be to get an air quality monitor and find out where you are—you can ignore the toast I made this morning—and start with the new EPA list, and start taking indoor air quality seriously.

As Paul Billings of the American Lung Association told Inside Climate News, “Why should the public care? Because particulate matter, PM pollution, soot, whatever you want to call it, it kills people. And it kills tens of thousands of people every year.” And it's in your home.

View Article Sources
  1. "What are the Air Quality Standards for PM?" United States Environmental Protection Agency.

  2. Mullen, N. A., et al. “Results of the California Healthy Homes Indoor Air Quality Study of 2011–2013: impact of natural gas appliances on air pollutant concentrations.” Indoor Air, vol. 26, no. 2, 2015, pp. 231–245., doi:10.1111/ina.12190