Air pollution

The New York Times reported that the US Environmental Protection Agency (EPA) will reconsider reducing the National Ambient Air Quality Standard (NAAQS) from its current 12 μg/m3 as an annual average. What’s new, and what’s a tired retread? 
The first general alarm about the lethal effects of community air pollution was sounded in London in December 1952 during a severe fog episode that shut the city down and flooded hospitals and morgues. Subsequent media discussions about the benefits of cleaner air often cite the World Health Organization's global estimate of 7 million air pollution-related deaths annually (about 12% of the total), primarily based on studies of long-term mortality differences among US cities during previous decades. More recent publications have focused on short-term temporal associations. So how do long- and short-term analyses relate?
Dear Director-Designee Regan: What an opportunity you now have to move the EPA's goals and objectives into the 21st century!
There are any number of papers supporting the idea that higher levels of air pollution are inversely correlated with poorer health outcomes. These studies all suffer from the fellow travelers of air pollution, traffic density, poverty, and lesser education which confound a clear linkage between air pollution and health. A new study offers a possibility.
Maybe barbeque and beach trips were modified over the weekend in the face of COVID-19. But surely it's appropriate to have a time-tested cautionary article go with America's birthday.
The more recent cases of COVID-19 seem to be coming from homes and family contacts, rather than from strangers. And there, with the "opening up" of social mobility, is an increasing interest in the spread and dispersion of airborne COVID-19 particles. There are lessons to be learned from atmospheric science, especially when it pertains to the dispersion of small particles.
Air pollution and COVID-19 share at least one attribute: their concentrations and your exposure differ inside and outside. Are we better off, indoors or outdoors?
As an avid reader of the New York Times, it pains me greatly to read about a familiar subject that has so many errors and misconceptions. Especially when COVID-19's impact on society is being discussed.
For those wanting to see the relative contribution of traffic and power generation to air pollution, consider this picture of Los Angeles. LA sits in a basin surrounded by mountains, I grew up there and can remember days when you can actually see the mountains.
Without a doubt, our world is now quieter since sheltering began, and we can imagine that the air smells sweeter. These are good things but purchased at the terrible costs of COVID-19 suffering and death and devastation of the global economy. The environmental scientist in me thought about lessons to be learned from our present situation.
"Although the epidemiology of COVID-19 is evolving, we have determined that there is a large overlap between causes of deaths of COVID-19 patients and the diseases that are affected by long-term exposure to fine particulate matter (PM2.5).” It is a great leap from overlap to claiming PM2.5 results in "excess" mortality from COVID-19. But what the heck, why let the fear generated by COVID-19 go to waste?
PM2.5 designates a near-ubiquitous air-polluting particle that frequently appears in the scientific literature as well as popular press news items. But few of us really know what they are talking about, mainly because it is just one characteristic of a complex category.