Beicology: Enjoy Summer While It Lasts as New Pollution Studies Warn of Bad Winter Days Ahead

How bad is the smog these days, really? Who is keeping tabs on the state of our drinking water? What has the government done about carbon emissions lately? In Beicology we turn our focus toward environmental news in the capital. 

Both pollution quality and quantity worsen in the winter

One year living in Beijing is usually all it takes to surmise that winters are just smoggier than summers. That's largely because the majority of the summer's pollution comes from the city's billowing cars while during the colder months those already high readings are exacerbated by coal-burning to maintain the city's heating, spiking levels of the chief airborne threats such as PM2.5, PM10, CO, O3, and NO2. As we previously reported, there may be reason to be optimistic about the upcoming winter period given that the first half of 2019 saw record lows in pollution levels, however, it remains to be seen what comes of Beijing's ever-fluctuating pollution policy and enforcement once the cold months finally arrive.

Nonetheless, studies of seasonal differences in the past couple of years have begun to investigate questions about how the seasons themselves can affect pollutants through temperature changes and other factors. Overwhelmingly, these studies’ conclusions are likely to make you want to wear a mask as you bundle up this winter (if you don't already).

PM2.5 is now understood to carry other harmful chemicals

By now, it's well understood that PM2.5 particles are more harmful than PM10 particles as their smaller size allows them to get deep into your lungs and also enter your bloodstream. Several studies based in Beijing (1, 2, and 3) have now determined that additional harmful and cancer-causing chemicals are more likely to attach themselves to PM2.5 in both lower temperatures and lower levels of humidity. That’s bad news for Beijing, where the winters are particularly cold and dry.  

Moreover, the chemicals in question are also more abundant in the winter, as they are a direct byproduct of the factories that power Beijing’s heating. While some amount of these chemicals are still around in the summer, they are more likely to be free-floating, meaning that they can more easily be dispelled from your lungs.

Yet another study from 2018 showed that PM2.5 particles are more likely to contain heavy metals than their summertime counterparts, including the likes of nickel and cadmium, which are more easily absorbed through the lungs than other metals. However, summer and spring have their downsides too as they give rise to higher levels of certain secondary organic aerosols, which can cause chronic inflammation of the respiratory tract.

Place matters too

In addition to seasonal comparisons, some of the above studies compared pollution quality in different locations in Beijing. Naturally, quality is worse in the south of the city, which is closer to the majority of power plants. Fortunately, residential areas typically experience much lower levels of the studied chemicals. Offices on the other hand typically have slightly higher levels of both free-floating and PM2.5 bound harmful chemicals, so if you've been meaning to talk to your boss about buying a long-overdue filtration device, it's probably best to do so now.

READ: I Want to Be-leaf: Beijing's Polluted Skies Helps Trees Grow Better

Photo: Uni You