High temperature is also foggy, functional masks do not letter

Mist is a combination of fog and haze, both of which are harmful to human health. Haze can particularly affect the respiratory and cardiovascular systems. Individuals suffering from chronic respiratory conditions such as asthma, chronic bronchitis, emphysema, or chronic obstructive pulmonary disease (COPD) may experience acute symptoms or worsening of their condition during hazy days. Prolonged exposure to haze can even increase the risk of lung cancer. Additionally, haze has serious effects on the cardiovascular and cerebrovascular systems, potentially leading to hypertension, coronary heart disease, stroke, angina, myocardial infarction, and heart failure.

Winter fog is often referred to as the "winter killer," and many people assume that haze is more common in cold seasons like winter or early spring. However, smog can also occur on hot summer days. For example, in Beijing, when the temperature reached 30°C, a yellow warning was issued by the meteorological department. Besides weather conditions, industrial emissions, vehicle exhaust, airborne dust, and microorganisms also contribute to the formation of haze.

To protect against the dangers of haze, many people turn to masks. While medical experts agree that masks can help reduce the intake of larger particles, they are not very effective against PM2.5, which refers to fine particulate matter with a diameter of 2.5 micrometers or less. These particles are so small that they can easily penetrate the lungs and bloodstream. Professional masks are primarily designed for larger particles, making them less effective at filtering out PM2.5.

Some companies market masks with features like anti-haze, anti-PM2.5, or anti-dust, but their effectiveness varies. According to tests conducted by consumer associations, only a small percentage of masks on the market provide adequate protection. The price of a mask does not necessarily correlate with its performance, and some high-priced masks do not perform better than cheaper alternatives.

Experts advise consumers not to blindly trust the claims made by manufacturers. It's important to choose masks from reliable sources and ensure a proper fit. Masks that are too loose allow harmful particles to enter. Disposable cup masks and folding masks made from non-woven materials with filtration properties are considered more effective. These should be discarded once they become uncomfortable or start to smell.

For individuals with respiratory or heart conditions, the elderly, and children, it's best to limit outdoor activity and keep windows closed. Washing the face and skin upon returning home can also help reduce exposure. If possible, using an air purifier at home is beneficial, but filters must be replaced regularly.

Many elderly people enjoy morning exercise, but it’s advisable to avoid outdoor activities during peak pollution hours, typically between 6 and 11 AM. The air tends to be cleaner in the evening, making it a safer time for physical activity.