Scientists have found an association between an increase in ozone exposure and short-term risk of death.
An international team of scientists has found an association between increased exposure to ozone and the short-term risk of death.
The findings, which appear in the BMJ, suggest that stricter air pollution policies would significantly reduce these deaths.
Ozone is a type of gas that consists of three oxygen atoms.
According to the United States Environmental Protection Agency (EPA), ozone has different health effects depending on where it comes from.
Stratospheric ozone helps shield life on Earth from the sun’s ultraviolet radiation and, as such, is a benefit to human health.
However, ground-level ozone (GLO) has associations with a variety of health issues. It is especially dangerous for older people, children, and people with diseases of the lungs, such as asthma.
According to the EPA, GLO forms when pollution reacts with sunlight. This pollution is produced through combustion, overwhelmingly from human-created sources that burn fossil fuels, such as vehicles and power plants.
According to the authors of the study, “ozone levels are predicted to increase with global warming,” and, as such, experts must gain a full understanding of the relationship between GLO and health issues.
The authors of the study note that while many studies document the adverse health effects of ozone exposure, they do not often address the increase of short-term deaths it causes.
Instead, studies have typically focused on longer-term general adverse health issues.
Quantifying the short-term effects of ozone exposure can be helpful when it comes to forming a policy on air pollution.
This is especially important given that air-pollution policies differ significantly around the world.
According to the article in the BMJ, the World Health Organization (WHO) suggest an ozone threshold of 100 micrograms per cubic meter of ambient air (100 μg/m3), the European Union (EU) put that figure at 120 μg/m3, the United States suggest 140 μg/m3, and finally China recommends 160 μg/m3.
By understanding the effects of GLO on short-term deaths, the study’s authors hope that consistent and evidence-based policy will be able to save a significant number of lives around the world.
The international team looked at data from 406 cities in 20 countries, focusing on the number of deaths and daily environmental effects. They covered a period between 1985 and 2015.
By identifying the daily average ozone levels, the types of particulate, the ambient temperature, and the humidity at each of the locations they covered, they were able to identify a possible association between changes in ozone levels and short-term deaths.
The team found that an increase of 10 μg/m3 in the ozone over 2 days resulted in an increased risk of death by 0.18%.
This equates to 6,262 additional deaths in the cities they studied attributable to ozone air pollution.
Drawing on data from the WHO, the team notes that over 80% of people who live in an urban area where authorities record air pollution levels are exposed to higher air pollution levels than the WHO’s recommended threshold of 100 μg/m3.
Further, however, the team also found that levels of ozone below the WHO’s threshold still had associations with significant numbers of deaths.
This suggests that not only should many countries around the world be far stricter with their air pollution standards, but the WHO could also make their recommended threshold lower in the interests of public health.
The team behind the study did note some limitations: the study is observational, which means that it cannot demonstrate why heightened ozone levels increase the number of short-term deaths.
Further, while the range of locations they studied was far greater and more consistent than previous studies, there were still some gaps. For example, the survey did not include any cities in Africa, the Middle East, or South America, which make up a significant portion of the world’s population.
Nonetheless, the research supports a growing body of evidence that air pollution has significant detrimental health effects. These are likely to increase as human-influenced global heating increases ozone levels further.