My grandparents arrived in Beijing in the 1960s to continue their undergraduate studies under a bright blue sky that contrasted sharply with the whitest clouds. Summers in Beijing were cool, and there was no need to wear short sleeves or shorts. At that time, there was no air conditioning or electric fans, and sleeping under a blanket at night was still necessary. Winters were frigid, with frequent heavy snowfalls that covered the entire city throughout the season. I've seen photos of my grandparents at the Summer Palace when they were young, dressed in thick cotton-padded jackets and pants, cotton shoes, hats, and gloves. They looked particularly bulky, making it hard to discern their figures and ages. My grandparents enjoyed Beijing's natural beauty and seasonal extremes without the worry of pollution intruding on their city's immaculate environment.

Let us go back to the early nineties when my parents were in Beijing for their university studies. Each summer, there was only about a month when short sleeves, shorts and air-conditioner were necessary. Despite the high temperatures, the air was dry. Standing in the shade of a tree felt cool. My mother moved to Beijing from Shanghai, and compared to the hot and humid summers in the south, Beijing was practically a summer paradise. Winters were still frigid, and she recalled squeezing onto buses to go to school while wearing long, thick, cotton-padded clothes, feeling like a big, clumsy bear. However, Beijing had indoor heating, so it was not too cold as long as she wasn’t outside for too long. Every time she stepped inside from the freezing outdoors, the warmth would envelop her, making her feel comfortable and happy. In contrast, she would get frostbite yearly in Shanghai, but it completely healed after moving to Beijing.

At that time, what troubled them the most was the sandstorm. My mother recalled that every time a sandstorm occurred, even during the day, the city was shrouded in a yellow haze that seemed dismal, just like dusk, and the visibility was only a few hundred meters. Bicyclists battled strong gusts as streetlights glowed blue in the distance, while most ladies wore veils over their faces. When she got home, she had to wash her face immediately and rinsed sand out of her mouth and nostril. Even with daily cleaning and firmly closed windows, there was always a coating of dust on the furniture. I wonder what happened. My father told me, this was the consequences of unchecked industrial expansion and environmental degradation while it was a fast-developing period for China. Human activities, including deforestation, overgrazing, and inadequate land management techniques, had made desertification worse in Northern China. Dust storms and increased soil erosion resulted from the land's diminished capacity to hold moisture due to the loss of plant cover. Unfortunately, Beijing was the worst hit by these environmental changes because it is situated downwind of these dry regions. He remembered clearly that Beijing had been struck thirteen times with a terrible sandstorm one spring.

Last ten years, the summers are extremely hot and humid. As soon as I go outdoors, I start sweating, feeling sticky, and suffocated. Even I, who love sports, want to stay in an air-conditioned room. My mother told me that it was very much like the climate in Shanghai, and people vividly called it "sauna days." Winters, on the other hand, seems less cold, today. There are only two or three snowfalls each year, and whenever the snowflakes started falling, I am overjoyed, feeling like they are gifts from God. I loved walking with my mother in the snow when I was little, leaving two sets of clear footprints behind us. As I grew up, I enjoyed having snowball fights and building snowmen with my classmates. Now, when it snows, the snow melts away within a few days, and there is almost no trace of the snowstorm in the city. After the snow melts, I immediately start looking forward to the next snowfall. In the autumn and winter of the 2010s, severe smog heavily troubled the people of Beijing, especially in 2015 and 2016, when I had just started primary school. The most common topic of conversation was Beijing's weather. Many people suffered from respiratory diseases, experiencing symptoms like coughing, allergies, and asthma. Some of my parents’ friends and their families moved away from Beijing because of the smog, relocating to southern China or other more temperate countries. My father explained that although large-scale afforestation in the Northwest and Inner Mongolia, as well as the construction of expansive green belts north of Beijing, were part of the government's efforts to counteract sandstorms, they had unintentionally trapped the chilly northern winds. As the economy expanded and earnings increased, additional problems surfaced, such as increased automobile emissions, the need to use coal for heating in the winter, pollution from industry and construction, and light radiation from skyscrapers. These elements worked together to produce poor air circulation, which trapped pollutants near the ground and raised PM2.5 to dangerous levels.[1]

I have vivid memories. Whenever haze came, the sky was a dusky cloud, the sun was hidden, and a heavy layer of fog enveloped the city, distorting distant vistas and stealing the color out of everything. The air was heavy with dispersed particulates, making breathing harder and causing symptoms like tightness in the chest and coughing. The teaching facility at my school had a fresh air system installed, meaning there was clean air inside. Once the PM2.5 level rose beyond 200, our outdoor activities were stripped away, and we were forced to stayed inside for rest of the day, and even for physical education, extracurriculars, and sports. Our parents were upset that we couldn't participate in outside activities, but they wanted us to stay inside all day to protect our health on smoggy days.

At that time, even though we were not yet ten years old, we would check the PM2.5 forecast every day because it affected our most cherished outdoor moments. One of the most memorable instances was when we were in third grade. To get us ready for our fourth-grade camping experience, our school hosted a camping event in the fall. We were ecstatic when we put up tents and cooked in the afternoon on the sports field. But by nightfall, the instructor declared that we had to relocate our tents to the gymnasium because the PM2.5 levels had risen beyond 300. We unwillingly lugged our tents and spent a restless night under the strong gym lights, our enthusiasm turning to dismay. It was my first "camping" experience and will always be a bittersweet memory. This incident reminded me how ubiquitous air pollution is in our everyday lives and our formative years.

I was curious why it went from sandstorms to haze. My grandfather is a professor who is very concerned about current affairs and news. He specifically searched for the information and then told me that the Chinese government had stepped up its efforts to clean up the sky for nearly twenty years. Reducing emissions has been made possible by moving the polluting industry to less populous locations, reducing the use of coal, slowing the explosive expansion of oil and gas, increaseing the utilization of greener energy sources, raising emissions limits, and boosting the development of alternative energy vehicles and associated sectors. It dawned on me that Beijing's air quality has greatly improved due to so many actions to work together. Bright days with blue skies and white clouds are becoming more common, and we may breathe and play freely without worrying about being restricted by air pollution. He emphasized again that it was an evidence of the success of well-coordinated environmental policy.

Why does Beijing experience sporadic dusty weather again during springtime? I raised a new question. My grandfather patiently explained that the development of five ventilation corridors in north Beijing has improved citywide air circulation, which has improved the effectiveness of pollution dispersal. Although Beijing and the northwest of China are heavily vegetated, China is nevertheless directly impacted by Mongolia's enormous deserts, which comprise 76% of its total area.  I suddenly understood that while the ventilation corridor brings north wind to Beijing, it also brings sand and dust from Mongolia. My grandfather nodded in agreement with my inference. Then he added that it emphasize the difficulties in controlling transboundary environmental concerns. Mongolia's deserts continue to be a major source of dust in Beijing, and solving this issue will require regional collaboration and worldwide cooperation in sustainable land management techniques.

Our survival cannot be separated from the climate, which is impacted by human activity and, in turn, affects our lives inexorably. My grandparents, my parents, and my experiences highlight the significant changes Beijing's environment over the past 60 years—from the city's beautiful skies to sandstorms and haze—serves as a microcosm of the larger issues affecting our world. The initiatives to stop desertification and enhance air quality are examples of the strength of group effort and the possibility of progress. It is the collective duty of all people to protect the environment; it is not the responsibility of a small number of people, a particular city, or a country. We should build on human’s past achievements and keep innovating in environmental research and policy as we move towards the future. A healthier and more sustainable world can only be achieved by investing in renewable energy sources, encouraging sustainable urban growth, bolstering international collaboration on environmental challenges, and enhancing public environmental awareness.

The road ahead of our common beautiful home is lengthy, and we have enormous obligations.  

[1] “PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.”