Don’t go outside, guys. Today, a new air pollution study carried out jointly by Transport for London and the Greater London Authority landed on our virtual doorstep, and it does not contain good news.

The study is the first in London, and quite possibly worldwide, to put a figure on the number of premature deaths caused by NO2, a noxious gas spouted by diesel engines and gas heaters. It uses data on 2010 pollution and deaths to quantify exactly how many people are dying early every year as a result of inhaling this gas, along with the small airborne particulates known as PM2.5s (so named because they’re up to 2.5 micrometres in diameter). 

First, some good news: a similar study carried out in 2010 measured only the effects of PM2.5s on Londoners’ health. It found that the particulates caused around 4,267 early deaths in 2008. This year’s study shows that this number has fallen to 3,537, thanks to lower levels of particulates in the air and a slightly different methodology, which restricts the number to man-made particulates, not naturally occurring ones.

Now for the not-so-good-news. The new data on NO2-related deaths shows that 5,879 early deaths in 2010 were caused by the gas, bringing the measurable total pollution deaths to 9,416:

Concerns around NO2 emissions were raised last year, when a King’s college researcher found that Oxford Street had the worst levels of it in the world. Initially, Mayor Boris Johnson reacted rather badly to the news:

There is hope, however, for Londoners’ lungs and their mayor’s outlook on the dangers of pollution. Johnson later retracted the statement with his tail between his legs, called for a diesel scrappage scheme, and ramped up work on London’s Ultra Low Emissions Zone, which should be in play by 2020. 

The GLA’s press release for this latest study notes that the data it contains is half a decade old, and schemes already in place should be having an effect: 

As this data is five years old, it does not include the impact of the many measures the Mayor has implemented since 2010 including tightening Low Emission Zone standards, delivering more than 1,300 hybrid buses and introducing age limits for taxis, nor the expected benefits of the Ultra Low Emission Zone in 2020. However, as a result of the Mayor’s policies by 2020 it is expected up to nearly four million life years will be saved for the London population over a lifetime. 

A bold claim. We’ll see.