An international team with Spanish participation has studied mortality in more than 400 cities in 20 countries for three decades. The results reveal that daily exposure to ozone pollution is behind 0.2% of deaths. According to the researchers, this mortality could be reduced with stricter air quality standards.
Daily exposure to ozone pollution in cities around the world is associated with an increased risk of death, according to an international epidemiological macro-study published this week in the journalBritish Medical Journal.
The work, led by the London School of Hygiene and Tropical Medicine (United Kingdom) and with the participation of a team from the Higher Council for Scientific Research (CSIC), highlights how stricter air quality standards could prevent thousands deaths each year.
Scientists have analyzed daily mortality, climate, and air pollutants in 406 cities in 20 countries around the world between 1985 and 2015, including data from 48 provincial capitals of Spain.
The findings, based on almost 50 million deaths, emphasize that more than 6,000 of them would have been prevented each year in these cities if countries had implemented stricter air quality standards, consistent with the guide values set by the World Organization of Health (WHO).
Highly reactive gas
Ozone is a highly reactive gas commonly found in urban and suburban settings. It is formed when pollutants react to sunlight.
Current air quality thresholds range from 100 micrograms per cubic meter of ambient air (according to WHO), 120 micrograms per cubic meter (according to the European Union directive), 140 micrograms per cubic meter (national standard for air quality US environment), and 160 micrograms per cubic meter (Chinese standard for air quality).
Recent work suggests that 80% of the world's population in urban areas is exposed to air pollution levels above the threshold set by the WHO.
Using data from the international collaboration networkMCC (Multi-City Multi-Country Collaborative Research Network)In which teams from around the world work to search for epidemiological evidence of associations between climate and health, researchers have obtained the average daily levels of ozone, particle pollution, temperature and relative humidity in each city to estimate the daily amount of additional deaths attributable to ozone levels.
Related to 0.2% of total mortality
On average, an increase of 10 micrograms per cubic meter of ozone during the current day and the previous one was associated with an increased risk of death of 0.18%.
"This finding reinforces the evidence of a possible direct association and is equivalent to 6,262 additional deaths each year or 0.2% of total mortality in the cities studied", details Aurelio Tobías, researcher at the Institute for Environmental Diagnosis and Water Studies (IDAEA).
According to Tobías, the results suggest that ozone-related mortality could potentially be reduced under more stringent air quality standards.
Furthermore, actions to reduce ozone pollution "would provide additional health benefits, even in regions that comply with current regulatory standards and guidelines," the researchers say.
"These findings have important implications for the design of future public health actions, particularly in relation to the implementation of mitigation strategies to reduce the impacts of climate change," concludes the IDAEA scientist.
Ana M Vicedo-Cabreraet al. “Short term association between ozone and mortality: global two stage time series study in 406 locations in 20 countries”.British Medical Journal.DOI: 10.1136 / bmj.m108.