精准控制燃烧，保护生态也守护健康

时文摘要

无论是意外还是人为火灾，烟雾都会影响健康，尤其危害附近社区。斯坦福大学团队提出新方法，通过调控木材湿度、火焰热度和氧气量，可减少 77% 致癌物质，兼顾生态与社区安全。

All fires, whether accidental or planned, produce smoke that can cause health and breathing issues, especially in nearby communities. In a recent study, however, scientists at Stanford University suggested ways to perform controlled burns with greatly reduced health implications. “There is clearly potential for improving controlled burn procedures, such that the health impact is reduced,” said Karl Töpperwien, who is the lead author. “We can essentially kill two birds with one stone — protect ecosystems while simultaneously protecting communities that would be otherwise at risk.”

To bring this new method to fruition, Töpperwien’s team collaborated with medical researchers, physicists, and chemical researchers. They built a laboratory-sized burning room where they burned samples of Eastern White Pine, one of the most common trees. Adjusting the moisture (湿度), heat, and oxygen level of the fires, the researchers conducted controlled burn experiments in their lab.

Their experiments revealed that fine-tuning three conditions can reduce PAH emissions by up to 77%. PAHs can cause cancer, lung damage, and lead to weakened immunity in those who breathe in smoke. The first condition concerns the moisture content of the fuel. They found that the wood should have a moisture content of 20-30% — too dry and it burns too fast, producing more smoke, but too wet and it smolders (闷燃), emitting high levels of PAH. Second, the heat intensity of the fire needs to be between 60-70 kW/m². Different levels of heat load promote different chemical reactions, which ultimately form PAHs: adjusting in the heat means finding the ideal condition where the least PAH is formed. Finally, the fires need to burn with oxygen levels of 5-15%. Too little oxygen can cause inefficient burns, leading to too much smoke, while too much oxygen can make a fire burn uncontrollably.

These three burn factors can effectively make controlled burns safer and cleaner for the environment and for communities living near fire-prone regions.

Ultimately, the question is whether these laboratory fires can be replicated in real-life controlled burns. “There will be some limitations to upscaling (大规模应用) this, but I clearly see a path towards making this technique more workable for a broader range of environmental conditions,” said Töpperwien.

1. 1. What is the main purpose of the Stanford University study?

A To prove the health risks of accidental fires.

B To find ways to make controlled burns safer.

C To identify the most harmful chemicals in smoke.

D To study the ecosystems in fire-prone regions.

2. 2. What can be inferred about the new burning method research from the text?

A It has been widely used in various environments.

B It completely eliminates the health risks of smoke.

C It requires collaboration across different research fields.

D It focuses only on protecting forest ecosystems.

3. 3. According to the study, which condition helps reduce PAH emissions?

A Using wood with a moisture content of 20-30%.