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Safely pass this vehicle if possible.

Here at EarthGarage, we are always thinking about pollution; when we walk downtown, when we go for a run with the pup, and especially when we drive. Lately we’ve wondered, are we exposed to the same pollutant concentrations while we drive in the car as we are when we walk around? We uncovered a study conducted in California that measured concentrations of air pollutants inside California commuter vehicles, and it revealed that levels inside the car are generally much higher than pollutant levels measured at the nearest monitoring station. Wow! We were already in favor of better fuel efficiency, and this confirmed that the condition of our vehicle does affect the health of the person (or family!) behind us.

The scientific study adjusted for freeway conditions, roadway types, time of day, vehicle type, two-driver-adjusted vent settings, and the relationships among pollutant concentrations inside and outside the vehicles compared to roadside and the nearest fixed site monitoring station. The researchers collected a number of 2-hour pollutant concentration measurements that included volatile organic compounds (VOCs) including PM2.5 and PM10, benzene, formaldehyde, carbon monoxide, and black carbon.

Some (surprising) results revealed that the levels of concentrations measured inside vehicles traveling ¬†in a carpool lane was much lower than those in the right-hand, slower lane. This finding adds to the benefits of carpooling – it cuts time, saves you money on gas, and it’s better for your health. ¬†Furthermore, there is a substantial influence from the individual in front of the test vehicles in the study- even for short periods- so we would suggest safely passing an unmaintained or stinky vehicle when possible because it will make a difference and reduce emissions streaming into your car. Also, vehicle ventilation systems do not significantly reduce gas phase pollutants inside the car, so perhaps rolling down the windows at higher speeds would be helpful to clear out the trail from the stinky guy in front of you.

More studies in other states are needed to further validate the study, but one can’t help but realize that pollution is hard to escape. Here at EarthGarage, we will continue to strive for better fuel efficiency and to reduce our emissions, for ourselves and our neighbors.


EarthGarage – Greener Car. Fatter Wallet.