Fine particulate matter is an air pollutant and they're very, very small
particles, so they tend to penetrate extremely deep into the lung, and the
sources of fine particulate matter are mostly power plants, and the cars in
traffic, and other types of combustion sources and I think it's
important to keep in mind that the main sources of greenhouse gases emissions
are also the main sources of fine particulate matter. Ozone here, the
ozone that we included in this study, is ground-level ozone, and ground-level
ozone is a form of also air pollutants and ozone comes from nitrogen oxide (NOx),
which the main source is traffic, and NOx interacts with temperature and
sunlight to form ozone.
In this study, we used long-term exposure to quantify
how much we breathe, the people breathe, air pollution. So long-term, in our study,
is defined by the yearly average of PM2.5 and warm season average of ozone.
So, speaking of the health factor of PM2.5 in the ozone, PM2.5 is so small, it can go deep
into your lung and even enter your circulation system. It can cause
systemic inflammation, can affect your vascular function, can also change
your heart rate variability, so many adverse health outcomes.
It can cause some cardiovascular disease, some respiratory disease, and even death.
And ozone, it can cause some irreversible damage to your lung tissues,
so multiple health effects.
So actually we used one supercomputer
provided by Harvard and, at some point, we used all the computational
power from their supercomputer. So, we took years of effort to build this data
framework, to build this data platform, to benefit future researchers, and also it's
worth mentioning that all the data either comes from government, or comes from some
open source. So, it's, in principle, reproducible.
So let's talk about what we found.
I think that by the ability of estimating exposure to air pollution in
areas that are unmonitored, we were able to estimate out the effects of air pollution at a
very, very low level, and that's something that has never been studied before, as
well as looking at whether there were some subgroups of our population that
were more vulnerable. So we found, in a very simple term, that if you were to
reduce long-term exposure to fine particulate matter by only one microgram
per cubic meter, which is a very little amount, we would be saving 12,000 lives a
year, and, for the effect of ozone, if we would lower only 1 ppb, one unit, in a
long-term exposure of summer ozone, we will be saving 1,000 lives a year.
Only specifically within the population that we studied, so only among
the senior citizens, that means that, if we were going, if we would have been
able to do a study on the whole population, probably the number of lives
saved would be much larger. We were also able to estimate with a tremendous
amount of precision the risk of death associated with exposures; they are very
well below the National Ambient Air Quality Standards, and I think that
speaks to the fact that we found such a strong and very precise
evidence of increased risk of death for exposure below the national standard,
it really speaks about the fact that we need to stringent our safety
standard even further. So, in terms of policy implication, I think the most
important message we hope to send across is that whenever we are
talking about climate change and whenever we are talking about steps to
reduce greenhouse gases emission, we tend to think about what will be the adverse
consequences a hundred years from now, two hundred years from now, with respect to
glaciers, with respect to extreme weather events, which is all absolutely true and valid,
but one thing that we hope to be, the message we hope to be sending in this
study is that, by acting on reducing greenhouse gases emission, we will be
acting on exactly the same sources that are contaminating our air, and, so, a step
forward about total climate change, it means immediate benefits, immediate
co-benefits in having our air more clean.