In modern life, commuters inevitably come into close contact with traffic exhaust fumes while rushing to work. Many reports show that traffic exhaust fumes have a negative impact on people's health, but to date, few studies have directly measured the level of air pollution inside vehicles, and little is known about people's exposure to traffic exhaust fumes during daily commutes.

　　Researchers from Duke University recently collected samples from highways and off-highway roads during peak commuting hours to assess in-vehicle PM2.5 levels. This study is part of the Atlanta Commuter Exposure (ACE) study. The researchers used a dithiothreitol (DTT) assay to analyze the oxidation potential of water-soluble extracts from PM2.5 filters.

　　The results showed that fresh exhaust fumes may contain a large amount of gaseous DTT-active substances. Researchers also found that their measured DTT activity was on average twice as high as that measured at roadside fixed monitoring stations. The relatively short sampling time (2 hours) of the quartz filter may have introduced errors into the experimental results. However, the researchers' current results still suggest that commuters on the road may be more exposed to PM2.5 with redox activity. Furthermore, the researchers also observed a strong correlation between water-soluble DTT activity and water-soluble organic carbon (WSOC), particularly among the "semi-volatile" WSOC components.

　　Therefore, these results from the researchers indicate that semi-volatile organic compounds are significant contributors to DTT activity, at least in environments where PM2.5 is primarily generated by vehicles.