London's infamous smoggy roads have been tackled by policy makers hoping to decrease air pollution in the city. Now, 10 years of data show that they're on the right track.

Scientists at King's College London analyzed a wealth of data to determine exactly how air pollution has been changing in London. Their report was published in the journal Environmental Pollution.

The study looked at levels of various pollutants from years 2005 to 2014 along 65 roads. Data shows that even though overall air pollution was down, there was a lot of variability among different roads.

Nitrogen dioxide (NO2) showed a double-digit percentage increases from 2005 to 2009 before it began to decrease at about 5 percent per year for the remaining years studied. The decrease was attributed to retrofitting new exhaust technology on older buses, Science Daily reports.

Fine particulate matter, the much maligned PM2.5, saw the most dramatic decrease after 2010 at an average of 28 percent per year. Black carbon also saw double-digit decreases during those years.

Preliminary pollutant particle's response to the policies is promising. However, NO2 levels are still above the recommended amount and there was no measurable change in levels of PM10.

"It is great that evidence shows that policies are starting to have an impact, but we need to expand on these to reduce the health burden from breathing polluted air," said Gary Fulller, a senior lecturer in Air Quality Measurement at King's College London. "Achieving the EU Limit Value for nitrogen dioxide by 2030 is likely to remain a challenge for many major roads in London."

Fuller added that to ensure that the amount of vehicles on London's road do not affect the decrease in pollution, tighter management of HGVs is needed. He also noted the importance of tackling the effect of particulate matter, from non-exhaust traffic emissions.

The study notes that new policies can be put in place to continue the positive trends observed in this study and address current areas that need improvement.

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