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Windshield washer fluid is an unexpected emission source, reports ACS
According to a report in the Journal of the American Chemical Society, alcohol ingredients in vehicle windshield washer fluid are a surprising source of real-world volatile organic compound emissions from cars, accounting for a larger fraction of emissions than previous estimates have suggested.
It says that notably, the levels of these non-fuel-derived gases will likely remain unchanged, even as more drivers transition from gas-powered to electric vehicles.
Cars' average carbon dioxide emissions have dropped by 25% since the early 2000s, according to the US Environmental Protection Agency, but this gas only accounts for part of the total. Other important components of emissions are volatile organic compounds - a broad classification of carbon-based molecules that are easily vaporised and which can contribute to ozone formation.
While some VOCs are released in exhaust, others may arise from the products used for car care, such as windshield washer fluid. Estimates from a national inventory of manufacturer statistics in the UK showed that car care products could be an even greater source of VOCs than exhaust emissions, but these numbers had never been verified experimentally until recently when Samuel Cliff and co-workers decided to measure the amounts of vaporised windshield washer fluid ingredients from cars on a real-world road and compare it to the inventory estimates.
To measure the VOCs emitted by vehicles, the researchers outfitted a van with several instruments, including a mass spectrometer, and parked it near a busy roadway. By comparing the van's measurements with those from a university site with minimal traffic influence, they calculated the average amount of vapour given off per car for each kilometre travelled for several key VOCs.
The measured values matched inventory estimates for aromatic compounds which are commonly monitored and regulated, but those for alcohols - key ingredients in windshield washer fluid - far exceeded inventory numbers. In fact, the release of two alcohols, ethanol and methanol, comprised nearly twice the amount of all VOCs released in exhaust.
It is thought that the discrepancy in alcohol emissions could be accounted for by including solvents from car care products in the inventory estimations, suggesting that these products are a significant, if unexpected, source of vehicle-derived pollutants. The researchers say that this finding has implications for future regulatory policy - especially as drivers transition to electric vehicles, which may have fewer emissions from fuels but will still need clean windshields.
Picture courtesy of Simon Kadula/Shutterstock.com
8th June 2023