Mobile Vocus CI-TOF Data Relate Volatile Chemical Products to Traffic Emissions and Population Density

Coggon, M. et al.
DOI: 10.1073/pnas.2026653118
Proceedings of the National Academy of Sciences, 2021

Volatile Chemical Product (VCP) Emissions Enhance Ozone and Modulate Urban Chemistry

VOCs emitted by industrial and consumer products, or “VCPs”, are important pollutants in urban areas. In fact, in major urban areas in the United States, this diverse class of chemicals can account for half of petrochemical volatile organic compound (VOC) pollution. In this study, researchers used mobile laboratories equipped with TOFWERK CI-TOF mass spectrometers to experimentally determine the relationship between VCPs, traffic emissions, and population density in large cities in the United States and in Europe. In addition to mobile drives comprising thousands of kilometers in the United States and Europe, one of the CI-TOF mass spectrometers was also deployed long-term in New York City to make detailed urban flux measurements.

Using mobile laboratory data, the researchers showed a clear enhancement of anthropogenic pollutants around each city. These pollutants comprise not only traffic emissions (such as benzene and other aromatics) and unambiguously manmade chemicals such as D5 siloxane (a personal care product ingredient), but also monoterpenes, which are emitted by trees but also used as fragrances in consumer products. Incredibly, the magnitude of the artificial-fragrance monoterpene emission from New York City was found to be comparable to that of a forest.

Finally, by combining the experimental data with air-quality modeling, the researchers were able to quantify the contribution of volatile chemical products towards ozone formation. Ozone is a health hazard and tightly regulated in most developed countries, and it is important for regulatory agencies to precisely understand the sources of ozone-forming chemicals. Data and modeling from this study indicated that VCPs are a significant contributor to urban ozone formation: more than half of the ozone formed from anthropogenic VOC pollutants could be traced back to VCPs.

Specific advantages of TOFWERK CI-TOFs in this study include:

Ease of operating the instrument in a mobile laboratory, and its dependability over long distances
Ability of the instrument to quantify many substances not easily measurable with other techniques
Good instrument characterization, enabling comparison between multiple instruments

TOFWERK scientists contributed the European data used in this study. Extensive mobile laboratory data from China are also available. Please contact us to learn more about mobile monitoring with Vocus CI-TOF mass spectrometers, or our measurements in Europe and in China.