Air Quality Awareness Week - Part 1 - Air Quality Basics


It has been a long time since the 1948 fatal air inversion of Donora, Pennsylvania and the killing London Smog of 1952. These two events contributed to the growing awareness that the chemicals and compounds we send into the air can have a detrimental – and sometimes deadly – effect on human health. Governments and average citizens around the world sprang into action and began learning about air pollution – what it does, where it comes from, how to control it, and what amounts can be considered “safe.”

Here in the US, the events in the late 40’s and early 50’s were immediately followed by Air Pollution Control Act of 1955, which created funding for air pollution research. This was followed by the Clean Air Act of 1963, where the research findings were utilized to create a set of federal regulations limiting various air pollutants. The Clean Air Act has been amended several times since it was written, most recently in 1990 – these are the regulations companies in the US follow today.

The Clean Air Act breaks air pollutants down into 2 categories. The first is the National Ambient Air Quality Standards, commonly called the NAAQS (“nacks”). These six pollutants – Nitrogen Oxides (NOx), Sulfur Dioxide (SO2), Carbon Monoxide (CO), Ozone (O3), Particulate Matter (PM10) and fine Particulate Matter (PM2.5) - can cause immediate health risks to individuals. The other categories of air pollutants are Hazardous Air Pollutants (HAPs). Many of these are substances such as carcinogens, which can have a chronic health effect over time.

When air monitors record levels of pollutants that exceed the NAAQS, that area can be designated as "nonattainment"... this basically means that the area is recognized as having unhealthy air and extra regulations are put into effect to help bring the air pollution back down to safe levels. There are certain exceptions to this... for example, an area gets a couple of freebies a year, and sometimes data can be thrown out if the state can prove the high levels were from a rare event that was not within the state's control (like a huge dust storm or wildfire).

 Each air pollutant has different deleterious effects on humans and the environment. Some air “pollutants” are neutral or even helpful when released in small quantities, but harmful in large quantities. Enough exposure to certain air pollutants can harm even the healthiest of individuals, as well as degrade the infrastructure of our cities and stunt crop growth. For the NAAQS, Primary Standards are the levels of pollutants considered to be safe for public health. Secondary Standards are created to protect everything else.

The allowed levels of these pollutants are based on current science believes to be safe for public health. EPA uses a committee of scientists called the Clean Air Science Advisory Committee (CASAC) to review the science and suggest updates to the standards every few years on a regular schedule.  

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