In 2009, I wrote an article describing a demand-controlled ventilation (DCV) strategy/technology referred to as “multiparameter DCV.”
For those not familiar with basic DCV, it is a process by which outside air in an HVAC system is varied based on the amount of CO2 in a space, since CO2 levels have long been recognized as a reliable indicator of indoor pollution originating from building occupants. The multiparameter approach added non-human pollutants, such as volatile organic compounds (VOCs), carbon monoxide (CO), and respiratory-size (<2.5-μm diameter) particles (PM2.5).
The rationale for adding VOCs and CO is obvious, since they are toxic and can be fatal to humans. However, the hazards of particulate matter may not be as obvious.
Particulates contain microscopic solids that are so small that they can be inhaled into the lungs, resulting in serious health problems. Particles less than 10-μm in diameter (PM10) can penetrate deep into the lungs and, in some cases, enter the bloodstream, and PM2.5 pose even greater health risks. Fine-particle aerosols can have viruses suspended on PM2.5 resulting in the spread of airborne infections. Sources of these airborne particulates include dust, dirt, soot, and smoke.
Although the Air Pollution Control Act of 1955 was the first federal legislation involving air pollution (it only provided funds for federal research in air pollution), it wasn’t until passage of the Clean Air Act of 1963 that controlling air pollution was actually addressed. The federal government’s role in air pollution control was expanded with the Air Quality Act of 1967, and the Clean Air Act of 1970 authorized the development of comprehensive federal and state regulations to limit emissions from both stationary and mobile sources. Major amendments were added to the Clean Air Act in 1977 and in 1990.
So, as we look at Earth Day 2023 in the rearview mirror now, what does air pollution – particularly that from particulate matter – look like 60 years after the first Clean Air Act?
For the past 24 years, the American Lung Association (ALA) has issued an annual “State of the Air” report. This year’s report, which examined both particulates and ozone, found that more than two-thirds (nearly 120 million) of Americans are breathing unhealthy air. According to the report, this is a significant improvement over last year; however, “the number of people living in counties with failing grades for daily spikes in deadly particle pollution was 63.7 million, the most ever reported under the current national standard.”
Here’s the ironic part: according to the ALA, “climate change is making the job of cleaning up the air more difficult.” The prime example is the increase in wildfires attributed, at least in part, to climate change, that have significantly increased the level of airborne particulates.
The answer is still the same: continue science-based – not political – efforts to reduce greenhouse gas emissions…for our own health and the health of our planet.
A regular contributor to HPAC Engineering and a member of its editorial advisory board, the author is a principal at Sustainable Performance Solutions LLC, a south Florida-based engineering firm focusing on energy and sustainability. He can be reached at [email protected].