Small rise in nitrogen dioxide in air ‘could be linked with higher death risk’

By Aine Fox, PA

A small increase in the level of nitrogen dioxide in the air could be associated with a higher risk of mortality, researchers have said.

Scientists looking specifically at this pollutant called for a tightening of air quality guidelines as a result of the study.

They said the findings suggest a need to revise guidelines on nitrogen dioxide “for greater public health benefit”, and urged a consideration of a regulation limit for daily mean nitrogen dioxide concentration.

The global study – which featured author contributions from London School of Hygiene and Tropical Medicine and King’s College London – considered 398 cities.

The analysis, published by the BMJ, included 62.8 million deaths, including 19.7 from cardiovascular disease and 5.5 million from respiratory disease, covering the study period from 1973 to 2018.

Levels of nitrogen dioxide, a common air pollutant, are measured in microgrammes (one-millionth of a gram) per cubic metre of air, or mcg/m3.

The study concluded that on average, a 10 mcg/m3 increase in nitrogen dioxide concentration on the previous day was associated with 0.46%, 0.37% and 0.47% increases in total, cardiovascular and respiratory deaths respectively.

The associations remained “robust” after adjusting for levels of other common air pollutants, they said.

The analysis “provides robust evidence for the independent associations of short term exposure to NO2 with increased risk of total, cardiovascular and respiratory mortality”, the researchers said.

They said while getting nitrogen dioxide down to zero “is infeasible”, the analysis “provides insight into the public health benefits of substantial reductions” in levels suggesting “considerable health benefits” from stricter control of nitrogen dioxide emissions and “tightening of the regulatory limits” in future revisions of World Health Organisation air quality guidelines.

They concluded: “These findings contribute to a better understanding of how to optimise public health actions and strategies to mitigate air pollution.”