Code Orange for Ground Level Ozone

 Received this email alert today on Air Quality. Thought I had left behind all the Air Quality Alerts in CA from the yearly wildfire smoke. 

"Air Quality Alert.... Tennessee Department of Environment and Conservation has issued a Code Orange Health Advisory for the Nashville Area... Ground Level Ozone concentrations may approach unhealthy levels... active children and adults and people with respiratory issues ... should limit prolonged outdoor exertion."

So what exactly is Ground Level Ozone (also often referred to as "bad" ozone).  

This is ozone that is not emitted directly into the air like some other pollutants. Instead, it forms in the atmosphere through a chemical reaction involving precursor pollutants in the presence of sunlight. Here is how it happens: 

1. Emission of Precursor Pollutants: The primary precursor pollutants for ground-level ozone are nitrogen oxides (NOx) and volatile organic compounds (VOCs). These pollutants are released into the air from various sources, including vehicles (especially those with internal combustion engines), industrial processes, and natural sources like vegetation

2. Chemical Reactions: Once in the atmosphere, NOx and VOCs undergo a series of complex chemical reactions in the presence of sunlight. This process is known as photochemical smog formation. Sunlight provides the energy needed to break down these precursor pollutants and form ground-level ozone

3. Ozone Formation: The chemical reactions between NOx and VOCs produce ground-level ozone (O3) and other secondary pollutants. Ground-level ozone is a key component of smog and is harmful to human health when present in high concentrations near the Earth's surface.

And what is Code Orange

Code Orange: This level signifies that air quality is unhealthy for sensitive groups which include active children and adults, as well as individuals with respiratory diseases such as asthma.