PM2.5 is what used to be called fine soot, tiny particles less than 2.5 micrometers or less in diameter, about 1/30th the width of a human hair. According to the EPA (for now, anyway), they are small enough that they get stuck in the lungs. A recent article in the Guardian says they can even penetrate the lungs and get into major organs, including the brain and testicles. They cause serious problems for people with heart or lung diseases, children, and older adults.
Now a new study published in Environmental Health Perspectives shows that they actually cause 31,000 deaths per year in America; 21,000 from burning what the President calls “clean, beautiful coal” and 10,000 from household heating with oil, natural gas and wood. The study also plots which states have the most deaths.
The number of deaths from residential combustion sources (RC) was really surprising. RC pollution is related to population density, having more sources and more people who are affected, so they are highest in dense northeastern states. In fact, in the dense northeast there are more deaths caused by residential sources than there are from power generation.
Ratios of RC-related deaths to EGU-related deaths vary greatly across source-states. Deaths from RC exceed those from EGUs for source-states in the Northeast and West Coast where population density is high, EGU coal combustion is limited, and wood or oil is used in some homes for heating. In contrast, deaths from EGUs exceed those from RC in source-states with appreciable EGU coal combustion and significant usage of electricity for home heating.
According to the study, “The vast majority of our 10,000 attributable premature deaths are likely related to wood combustion given its dominance in primary PM2.5 emissions.” However the high numbers of deaths in Ohio, Pennsylvania and New York State from residential combustion are scary. The numbers in Oregon and Washington are certainly leading me to rethink my previous position on wood burning stoves in low-density rural areas.
Total health impacts from RC are driven by POC [primary organic carbon] emissions across the United States. The number of deaths caused by each source-state is related to population, which influences both the extent of residential emissions and size of the exposed population, the need for home heating, and the degree to which wood, oil, and gas are used. As such, states causing the most deaths from RC have large populations within the state and immediately downwind and experience cold weather.
The fact that 21,000 people die each year because of the particulate pollution from coal-fired power generation is disgraceful; that the government is in fact rolling back regulations and promoting coal consumption is scandalous. And 10,000 deaths from residential combustion is shocking.
None of this even takes into account the contribution from car exhaust; it become clearer every day that we have to decarbonize our economy, not just because of carbon dioxide and climate change in the longer term, but because it is killing us directly right now.