In winter time, cold temperature leads to an increase in using heaters of course. And when the electricity source is notably based on coal power plants, then gas emissions (and particles) increase as well leading to higher pollutant concentration.
Air pollution in China is well known. Satellite observations as evidence show a strong increasing trend of NO2 column concentrations since 1995 in China (Irie et al., 2005; Richter et al., 2005; van der A et al., 2006). The main anthropogenic emissions of NOx in China are from transport and coal-fired power plants (Liu et al., 2015; Saikawa et al., 2017; Li et al., 2017). Because of the rapid implementation of new technologies and air quality control regulations for power plants and vehicles in China, their emission factors and activities are also changing with time. In spite of major reductions the last 7 years thanks to very supportive governmental decisions, it still remains an issue.
Pictures below, from NASA MODIS Aqua let us imagine how suffocating this air may remain these days. TROPOMI Sentinel-5 Precursor observations indeed show high concentrations of not only NO2 – nitrogen dioxide, and CO – carbon monoxide. Efforts in reducing emissions due to the electricity generation and vehicles must continue to ensure a better health for the whole population.