Since the winter of 2013, Northeast Asia is deep in smoke and haze, serious air pollution caused by the hazy days become the most concerned about environmental protection and health issues. The most serious period, the Ministry of Environmental Protection has made the following notification: most of the central and eastern parts of China are hazy, affecting an area of 1.43 million square kilometers, accounting for about 15 percent of the country’s land area. Of the 39 cities in and around Beijing, Tianjin, Hebei and surrounding areas, 20 were heavily polluted or more. And this serious air pollution was not gradually ended until the end of February, which is still fresh in everyone’s mind. Air pollution is an unavoidable environmental, social and health problem of industrialization, and many countries and historical cities have suffered from serious hazy days during the process of industrialization and industrial chain upgrading in the world. Now, as the region with the brightest economic growth rate, Northeast Asia also bears the brunt of this round of issue fermentation, threatening the health of the people all the time. What’s even more concerning is that air pollution can not only damage our physical health, but also pose a challenge to mental health. What kind of people are more likely to be affected by air pollution and ruin their mood? A recent Korean study reported in the internationally renowned Journal of Affective Disorders suggests that the susceptibility of air pollution to mood problems is also tied to the underlying health background: patients with chronic conditions such as coronary heart disease, asthma and diabetes are more likely to suffer depressive episodes due to air pollution. The team collected information and health backgrounds (at least one of these chronic diseases) of nearly 5,000 patients who visited psychiatric departments for depressive episodes between 2005 and 2009, as well as air testing data for the corresponding time periods. It was found that PM10, sulfur dioxide, nitrogen dioxide, and carbon monoxide together constitute an air pollution model that was strongly associated with depressive episodes in these patients and even caused the first episode of depression in some of them. The cause of this association is unclear, but the researchers speculate that these chronic diseases also have physical and psychological properties, often with dysfunction of the hypothalamic-pituitary-cortical axis (the “axis” that is closely related to our mood). The large number of inflammatory factors in the air pollution model may have exacerbated this abnormality and constituted the biological basis for the above patients’ vulnerability to depression. Of course, we should not be too frightened by this possibility. We should understand the root cause of air pollution, look at the long-term nature of treatment with a scientific and rational mind, and improve our living and consumption habits from our own perspective, so that the panic and impetuous demands for environmental protection and health will not become a “haze” in our hearts.