In a new study, researchers found that even small increases in nitrogen dioxide levels in the air may be linked to increases in heart and respiratory deaths.
The findings suggest a need to revise and tighten the current air quality guidelines, and to consider stricter regulatory limits for nitrogen dioxide concentrations.
The research was conducted by a team at Fudan University and elsewhere.
Nitrogen dioxide (NO2) is a common air pollutant formed by burning fuel for things like transport, power and industrial processes.
It is measured in micrograms (one-millionth of a gram) per cubic meter of air or μg/m3.
World Health Organization (WHO) air quality guidelines currently recommend that nitrogen dioxide levels should not exceed an annual average of 40 μg/m3.
Many studies have reported the effects of short-term exposure to NO2 on health, but most have been based on small samples, covered limited geographical areas, or used different study designs, so results are inconsistent.
In the study, the team set out to test the short-term associations between NO2 and total, heart, and respiratory deaths worldwide.
Their findings are based on daily concentrations of nitrogen dioxide from 398 cities in 22 low to high-income countries/regions over a 45-year period (1973 to 2018).
They found on average, a 10 μg/m3 increase in NO2 concentration on the previous day was linked to 0.46%, 0.37%, and 0.47% increases in total, heart, and respiratory deaths, respectively.
The researchers estimate that the proportion of deaths attributable to NO2 concentration above the zero levels was 1.23% across the 398 cities.
And while they acknowledge that reducing NO2 to zero is infeasible, they say their analysis “provides insight into the public health benefits of substantial NO2 reductions.”
The study is published in The BMJ. One author of the study is Xia Meng.
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