Aerosol Particles in the Atmosphere, HCPA works to improve ozone science; supports air quality initiatives.

Written on: November 1, 2018 by Nicholas Georges

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 contain a number of different ways that States can improve their air quality, including the regulation of emissions from consumer and commercial products, even though these emissions are a much 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 early 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. If you would like to learn more about our efforts or have questions regarding VOC regulations, please contact me at SPRAY



1Voiland, Adam. (2010, November 2). Aerosols: Tiny Particles, Big Impact. Retrieved from

2United States Environmental Protection Agency. (2018, June 20). Health and Environmental Effects of Particulate Matter (PM). Retrieved from