Ozone pollution is associated with increased CV morbidity
Ozone pollution and hospital admissions for cardiovascular eventsLiterature - Jiang Y, Huang J, Li G, et al. - Eur Heart J. 2023 Mar 10;ehad091. doi: 10.1093/eurheartj/ehad091.
Introduction and methods
Ambient ozone (O₃) is a harmful air pollutant, which has adverse effects on various aspects of human biology, including inflammation, oxidative stress, endothelial function and autonomic imbalance [1-3]. Epidemiological studies have demonstrated that ambient O₃ is associated with increased risk for CV mortality [4-7]. However, data on the effects of O₃ on CV morbidity are lacking.
Aim of the study
This study aimed to investigate whether there is an association between acute exposure to ambient O₃ and CV morbidity.
This was a large study that used national health insurance data of 258 million people across 70 cities in China, representing 18% of the total general population of China. Hospital admission data from 1 January 2015 to 31 December 2017 were included. During this period, a total of 6,444,441 daily hospital admissions for major cardiovascular diseases were registered. The authors modelled the risk per 10 µg/m³ increase in acute exposure to ambient O₃ (daily 8h maximum concentrations) per 2-days with different CV diseases.
The main outcome was CV hospitalization.
- Acute ambient O₃ was associated with an increased risk in CV hospitalization (increase per 10 µg/m³ increment in 2-day average daily 8 h maximum O₃ concentrations for CHD: 0.46% (95%CI: 0.28-0.64), angina pectoris: 0.45% (95%CI: 0.13%-0.77%), AMI: 0.75% (95%CI: 0.38%-1.13%), ACS: 0.70% (95%CI: 0.41%-1.00%), HF: 0.50% (95%CI: 0.24%-0.77%), stroke: 0.40% (95%CI: 0.23%-0.58%), and ischemic stroke: 0.41% (95%CI: 0.22%-0.60%). However, the risk in hospitalization for hemorrhagic stroke was lower, difference -0.37% (95%CI: -0.64% to -0.09%) per 10 µg/m³ increase in O₃.
- The effects of acute ambient O₃ exposure on CV hospitalization were independent of other air pollutants such as fine particles, inhalable particles, sulfur dioxide, nitrogen dioxide and carbon monoxide.
- Excess risk of CV hospitalization was detected when people were exposed to O₃ of ≥70 µg/m³ daily ambient 8-h maximum ozone concentrations compared to O₃ of <70 µg/m³, and this ranged from 2.49% (95%CI:0.85-4.15) for HF and 3.51% (95%CI:2.22-4.82) for CHD.
- Excess risk for CV hospitalization was detected in people exposed to O₃ of ≥100 µg/m³ (O3 pollution above air quality standards as defined in the WHO guideline) compared to O₃ of <70 µg/m³ (difference 6.52% (95%CI: 2.92-10.24) for AMI, 6.47% (95%CI:3.62-9.39) for ACS, 4.91% (95%CI: 3.21-6.64) for CHD, 4.57% (95%CI: 1.85-7.36) for angina pectoris, 3.87% (95%CI: 1.72-6.08) for HF, 3.45% (95%CI: 1.57-5.37) for ischemic stroke, and 3.38% (95%CI: 1.73-5.06) for stroke.
- There was an annual increase in CV hospitalization attributed to ambient O₃ from 2015 to 2017.
This study demonstrated that exposure to ambient O₃ is associated with increased hospital admission risk for CV events, independently of other air pollutions. This risk was considerably higher in people exposed to ambient O₃ above air quality standards as defined by the WHO (>100 µg/m³), indicating that prevention of high O₃ pollution is warranted for CV risk management. These results are especially alarming in the context global warming, as ambient O₃ is higher with high ambient temperature .