The study by Li et al¹ addressed a crucial public health issue. Air pollution has been recognized as an important cause of excess cardiovascular morbidity and mortality. Particulate matter appears to be particularly important in that regard. Yet much of the evidence is based on epidemiological surveys. Indeed, the mechanisms driving the increase in cardiovascular risk are poorly understood, and data from properly conducted trials testing preventive measures are scarce.

The investigators should be …

中文翻译：

---

Jordan和Biaggioni关于文章“颗粒物暴露和压力激素水平：空气净化的随机，双盲，交叉试验”的信函

Li等人¹的研究解决了一个关键的公共卫生问题。空气污染已被认为是导致心血管疾病发病率和死亡率过高的重要原因。在这方面，颗粒物质似乎特别重要。然而，许多证据是基于流行病学调查的。实际上，人们对导致心血管风险增加的机制了解甚少，并且缺乏通过适当的试验来测试预防措施的数据。

调查人员应……