Pressure Points
Aerosol Particles
in the Atmosphere
Have you ever wondered how clouds form and why most
of them don’t produce rain? Or why a particular sunset
appears redder than usual? Have you heard of terms such
as primary organic aerosols (POA) or secondary organic aerosols
(SOA) and wondered what these things are and how they relate to
aerosol products? As a SPRAY reader, you likely think of the term
“aerosol” as referring to a self-pressurized product which typically
dispenses a foam, paste, powder, liquid or gas through the use of a
propellant; however, “aerosol” means so much more…
When it comes to our environment, “aerosol” is a term used to
describe particles that have become suspended in the air. Aerosol
particles can come from natural sources such as plants, the ocean
or volcanoes. These tiny particles can be found everywhere in the
air—even over the ice of Antarctica and inside the International
Space Station!
Human activities also produce aerosol particles, some from
obvious sources such as car emissions and others that we never
think of, like the food we cook or the oils produced by our skin.
And yes, aerosol particles in the atmosphere can also result from
the use of consumer and commercial products; however, you may
be surprised to learn that a majority of the aerosol particles in our
atmosphere come from nature, not human activity.1
Just as with the particle size of an aerosol product, the size and
distribution of aerosol particles in the atmosphere play a critical
role in their behavior and lifespan. Aerosol particles vary in shape
and size from a diameter of 100 microns to a few nanometers.
Unfortunately, today’s society often connects aerosol particles
with our air pollution problems.
You’ve heard of ozone before, a beneficial chemical in the
stratosphere that shields us from the sun’s ultraviolet light, but
ozone presents a problem in the troposphere (ground level) as it
affects vegetation, ecosystems and human health. Ozone is not
emitted directly into the atmosphere but is the result of chemical
reactions between oxides of nitrogen (NOx) and volatile organic
compounds (VOC) in sunlight.
While the direct emission of organic matter (POA) into the
atmosphere is straightforward, the formation of SOA through the
oxidation of VOCs is far more complicated.
SOA is a major component of particulate matter; however,
research is ongoing to determine the mechanisms of its formation.
Particulate matter has become of great concern due to the
health risks it poses, including respiratory and cardiac issues, and
its effects on the environment, such as degradation to various
ecosystems and farmlands.2
The U.S. Environmental Protection Agency (EPA) regulates
both the levels of ozone and particulate matter through the Clean
Air Act (CAA). EPA has set National Ambient Air Quality Standards
(NAAQS) for six pollutants. In addition to ozone and particulate
matter, EPA has set standards for carbon monoxide, lead,
nitrogen dioxide and sulfur dioxide. States that do not meet the
standard for one or more have to submit a state implementation
plan (SIP) to the EPA. The SIP outlines the measures that the
state will take to improve the air quality and meet the standards in
non-attainment areas. A SIP can have a number of different ways
that States can improve air quality, including the regulation of
emissions from consumer and commercial products, even though
these emissions are a smaller piece of the pie than other sources.
As States continue to work towards the improvement of their
air quality, manufacturers often work alongside them to develop
new and innovative ways to reduce their products’ impacts on the
environment while maintaining the necessary level of performance.
That’s why it is critical to better understand the mechanisms
of how ground-level ozone and particulate matter form so
that we can work with regulators to adopt regulations that meet
our shared goal of improving the air quality across the U.S.
While it is often flawed science that generates the headlines in
the media, there is good science being performed and studied by
government, academics and even industry to better understand
the science of aerosol particles. As representatives of industry, we
must identify and support scientists that are trying their best to
find answers to the questions we haven’t thought of yet. We must
evaluate any new research while continually applying rigorous
scientific reasoning and be nimble and willing to accept new ideas
that improve and expand our current understanding of science.
There are conferences each year for various regions to present
and discuss the ongoing science of aerosol particle research, and
the International Aerosol Research Assembly (IARA) holds an
International Aerosol Conference (IAC) once every four years
to bring together scientists from around the world. The most
recent IAC was hosted in St. Louis in September, which HCPA
attended.
For more than 30 years, HCPA and our member companies
have worked collaboratively with legislators, regulators, NGOs
and stakeholders at all levels of government to significantly
improve air quality in California and across the U.S. HCPA and
its members remain committed to providing sustainable products
that help States achieve air quality standards and allow consumers
and workers to live productive and healthy lives.
In September, HCPA hosted a webinar series that provided
a comprehensive overview of State and Federal clean air VOC
regulations affecting consumer and commercial products, in addition
to offering an understanding of the complex considerations
needed to assure product compliance. Attendees of the webinar
series have received a copy of the recordings for future viewing;
however, if you did not register for the series, recordings are now
available on our website: thehcpa.org. If you would like to learn
more about our efforts or have questions regarding VOC regulations,
please contact me at ngeorges@thehcpa.org. Spray
10 Spray November 2018
NICHOLAS GEORGES
Director, Scientific Affairs, HCPA
HCPA works to improve ozone science; supports air quality initiatives
1Voiland, Adam. (2010, November 2). Aerosols: Tiny Particles, Big Impact. Retrieved from
https://earthobservatory.nasa.gov/Features/Aerosols
2U.S. EPA. (2018, June 20). Health & Environmental Effects of Particulate Matter. Retrieved from
https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm