According to a recent study, “badly tuned” cars and trucks are huge polluters. Though they makeup just one quarter of the vehicles on the road, they’re responsible for most vehicular air pollution.

Air pollution is linked to a host of health ailments, many of which can be fatal. From asthma in children to heart disease, cancer, and overall increased rates of premature death in adults — the problem is worth public attention, especially in places with particularly poor air quality. And the new study found that controlling the problem may be easier than we first thought, considering that just 25 percent of cars on the road are responsible for a whopping 90 percent of vehicular air pollution.

According to the study, published in the journal Atmospheric Measurement Techniques, “badly tuned” cars are responsible for most of the air pollution. Researchers at the University of Toronto looked at 100,000 cars as they drove past air sampling probes on one of Toronto’s major roads.

The study found that 95 percent of black carbon, also known as soot, 93 percent of carbon monoxide, and 76 percent of volatile organic chemicals (like benzene, toluene, ethylbenzene, and xylenes), were caused by just one quarter of cars on the road. Volatile organic compounds are often carcinogenic.

“We used to think that living near a major road meant that you lived near a lot of air pollution,” Greg Evans, a chemical engineer at University of Toronto said in a statement. “But what we’re finding is that it’s not that simple, someone living right on a major road in the suburbs may not be exposed to as much pollution as someone living downtown on a side street near many major roads.”

Evans and his team found that policy changes need to better target cars that are causing the majority of the air pollution.

“The ultrafine particles are particularly troubling,” says Evans. “Because they are over 1,000 times smaller than the width of a human hair, they have a greater ability to penetrate deeper within the lung and travel in the body.”

The researchers also found that building roadways near those that are particularly vulnerable to air pollution is also problematic. Busy roadways near schools, hospitals, daycare centers, and senior residences may put people at risk to some of the health problems associated with poor air quality.

“The most surprising thing we found was how broad the range of emissions was,” says Evans. “As we looked at the exhaust coming out of individual vehicles, we saw so many variations. How you drive, hard acceleration, age of the vehicle, how the car is maintained – these are things we can influence that can all have an effect on pollution.”

Unless we see smog in our everyday lives, we often forget about the impact of poorly tuned vehicles, but this research is a good reminder that air pollution can take its toll and poorly maintained cars can have a larger effect than we ever could have imagined.

Related on EcoSalon

Toxic Air Pollution: 90% of Chinese Cities Fail Quality Standards

3 Ways China Is Working To Clean Up Its Air Pollution

Beijing Air Quality Prompts Artist to Sell ‘Fresh Air’ in a Jar

Image of car exhaust from Shuttershock