I partially agree with you. They need a better explanation of what they were measuring for and how they came to their conclusions. Also PM2.5 may be too large to capture all the exhaust particles, a quick Google search shows some results saying 2.5 for combustion particles and others saying 2.5-1.0. PM2.5 is generally considered to be the most harmful to human health and they stay in the air longer than larger particles so maybe that’s why they chose to only measure that?
But, just because the volume of gas a car uses far exceeded the volume of tire it uses does not mean that the burning of gas creates more pollutants. Theoretically, the only products of combustion are water and carbon dioxide. We know that we don’t get perfect combustion, there are additives that affect things, the time in the combustion cylinder isn’t ideal, and the air to gas ratios aren’t always right. If we had perfect combustion water and CO2 may not be considered pollutants. Both occur naturally and have natural processes to be reused. Generally we do think of CO2 as a pollutant because we produce it in much great quantities than it naturally would be created. They exclude CO2 from their study, we know this because CO2 is much smaller than PM2.5.
It didn’t really occur to me to consider an interpretation of “emissions” that excludes CO2. Had they stuck with the word “pollutant,” then sure, but what they said was “emissions.”
There’s probably some reasonable interpretation of these findings that’s productive and useful, but I think whoever wrote this is playing a bit fast and loose.
I partially agree with you. They need a better explanation of what they were measuring for and how they came to their conclusions. Also PM2.5 may be too large to capture all the exhaust particles, a quick Google search shows some results saying 2.5 for combustion particles and others saying 2.5-1.0. PM2.5 is generally considered to be the most harmful to human health and they stay in the air longer than larger particles so maybe that’s why they chose to only measure that?
But, just because the volume of gas a car uses far exceeded the volume of tire it uses does not mean that the burning of gas creates more pollutants. Theoretically, the only products of combustion are water and carbon dioxide. We know that we don’t get perfect combustion, there are additives that affect things, the time in the combustion cylinder isn’t ideal, and the air to gas ratios aren’t always right. If we had perfect combustion water and CO2 may not be considered pollutants. Both occur naturally and have natural processes to be reused. Generally we do think of CO2 as a pollutant because we produce it in much great quantities than it naturally would be created. They exclude CO2 from their study, we know this because CO2 is much smaller than PM2.5.
It didn’t really occur to me to consider an interpretation of “emissions” that excludes CO2. Had they stuck with the word “pollutant,” then sure, but what they said was “emissions.”
There’s probably some reasonable interpretation of these findings that’s productive and useful, but I think whoever wrote this is playing a bit fast and loose.