An Open Letter to the U.S. Environmental Protection Agency on Air Quality

Dear Director-Designee Regan:

What an opportunity you now have to move the EPA's goals and objectives into the 21st century!

The goal should be to establish evidence-based regulation understandable to the public, with clear accountability. Air pollution regulation is still based on concepts from 50 years ago when the environment was quite different and the science was in its infancy. Objectives should include updating the air quality monitoring system based on existing science and establishing a new health-effects study cohort that reflects current and future populations. 

Any health benefits of the $65 billion we have spent in reducing outdoor air pollution have not been quantified, even though today’s cleaner air is undoubtedly a public good. We need an accounting of our expenditures – how has public health improved? Ambient levels of CO and SO2 are now so low that the EPA should declare victory and divert those monitoring resources to more pressing problems.

Climate change is one of them, and the EPA should add heat-trapping air pollutants to its ambient monitoring program, specifically methane and black carbon. Those pollutants are more potent per unit than CO2 but are usually mentioned only in passing in the climate debate. Their contributions to atmospheric heating have been well established, but we have no idea how much is out there and how significant their contributions may be. Ambient monitoring is the first step to achieving the goal of reduced emissions. CO2 is globally distributed and is a pollutant beyond the control of individuals. By contrast, methane and black carbon are local, and communities with a sense of local ownership can address these problems – but they require ambient air monitoring to establish baselines.

We are indoors upwards of 85% of the time, more so for those most at risk. The EPA’s Office of Radiation and Indoor Air provides guidance to the public, but indoor air quality has never been considered in the epidemiology studies used to set regulatory standards. In much of our nation, outdoor air is now cleaner than indoor, which is why “safe” levels of outdoor fine particulates (PM2.5) and other air pollutants cannot be determined from epidemiology alone.      

PM2.5 poses other issues for the EPA

Unlike other regulated pollutants, it is a mixture of various particles, some toxic, many not, defined only by the collection method with no chemical specification. PM2.5 encompasses a wide range of particle sizes, but only the smallest can enter the bloodstream and travel to organs that might be at risk. Such nanoparticles comprise a minuscule fraction of PM2.5 mass and require more sophisticated measurement methods. While there is no toxicological support for PM2.5 as a collection of unspecified mixtures and particle sizes, there are clear toxic effects for specific types of particles, namely heavy metals and certain carbonaceous compounds. Controlling black carbon may provide health and climate benefits, but widespread routine monitoring is a prerequisite. Despite the increasing relevance of nanoparticles to our health, they have never been monitored in the U.S. nor included in air pollution epidemiology studies as is being done in Europe.

The epidemiological studies underpinning the regulation of fine particles and other pollutants were based on epidemiological studies of Caucasian middle-class cohorts recruited 40 years ago. They are no longer representative of our country. Both physiology and environmental justice demand that more inclusive cohorts be recruited and studied. And unlike prior work, additional social determinants of health, including income, housing, exposure to green spaces, and traffic, must be considered. Now is always the best time to start such a study, which should be under the National Institute of Health's aegis and kept clear of regulatory issues.       

In short, take the opportunity to return science to the agenda, control the pollutants known to be toxic, monitor the air people actually breathe, establish accountability based on the current population, and bring the climate change issue into local ownership. The nation is waiting.


Fred Lipfert, Ph.D.