Ozone from fireworks: Chemical processes or measurement interference?

Area of Science:

• Atmospheric Chemistry
• Environmental Monitoring

Background:

• Fireworks have been considered a source of atmospheric ozone through photolysis of nitrogen dioxide (NO2) or oxygen (O2).
• Previous studies suggested fireworks contribute to nighttime ozone levels during displays.

Purpose of the Study:

• To investigate the validity of ozone signals detected during firework events.
• To differentiate between actual ozone formation and interference in ozone monitoring.

Main Methods:

• Laboratory experiments were conducted on two types of fireworks (low and high energy).
• Field experiments were performed to assess real-world firework display conditions.
• Ozone monitoring was analyzed in conjunction with particulate matter, volatile organic compounds (VOCs), nitrogen oxides (NO), and sulfur dioxide (SO2) measurements.

Main Results:

• Ultraviolet (UV)-based ozone monitors are susceptible to interference from aerosols and specific VOCs.
• High-energy fireworks produced high particulate matter and low VOCs, with artificial ozone signals reduced by aerosol filters.
• Low-energy fireworks released significant VOCs, primarily from burning cardboard, which interfered with ozone monitors, with benzene and phenol identified as potential interferents.
• Observed nighttime ozone signals (3-8 ppbv) in Jinan and Beijing during Chinese New Year correlated positively with NO and SO2, indicating monitoring interference.

Conclusions:

• The common understanding of ozone formation from fireworks is likely incorrect.
• Aerosols and VOCs emitted by fireworks, particularly from cardboard combustion, significantly interfere with UV-based ozone monitors.
• Observed ozone signals during firework events are largely artificial, influenced by combustion byproducts rather than actual ozone production.