The strict Clean Air Action Plan has been in place by central and local government in China since 2013 to alleviate haze pollution. In response to implementation of the Plan, daytime PM2.5 (particulate matter with aerodynamic diameter less than 2.5 um) showed significant downward trends from 2015 to 2019, with the largest reduction during spring and winter in the North China Plain. Unlike PM2.5, O-3 (ozone) showed a general increasing trend, reaching 29.7 mu g m(-3) on summer afternoons. Increased O-3 and reduced PM2.5 simultaneously occurred in more than half of Chinese cities, increasing to approximately three-fourths in summer. Declining trends in both PM2.5 and O-3 occurred in only a few cities, varying from 19.1% of cities in summer to 33.7% in fall. Meteorological variables helped to decrease PM2.5 and O-3 in some cities and increase PM2.5 and O-3 in others, which is closely related to terrain. High wind speed and 24 h changing pressure favored PM2.5 dispersion and dilution, especially in winter in southern China. However, O-3 was mainly affected by 24 h maximum temperature over most cities. Soil temperature was found to be a key factor modulating air pollution. Its impact on PM2.5 concentrations depended largely on soil depth and seasons; spring and fall soil temperature at 80 cm below the surface had largely negative impacts. Compared with PM2.5, O-3 was more significantly affected by soil temperature, with the largest impact at 20 cm below the surface and with less seasonal variation. (C) 2020 Elsevier Ltd. All rights reserved.

Biomass burning emitted aerosols are subject of concern in different disciplinary researches from different perspectives (climate change science from shift of balance in radiative forcing having severe repercussions on global ecosystem, while air pollution science from public health concern). By exploring particle number emission factors (PNEF), particle size distributions, and volatility of emitted ultrafine particles from burning rice straw, potential annual release of aerosols from rice straw combustion to the global atmosphere is estimated, and the issue of their management from such interdisciplinary perspectives is discussed. Between an estimated as low as 15% and as high as 75% of rice straw being burnt globally, the global annual estimate of emitted aerosols mounted from an order of 10(21) particles/yr to the order of 10(22) particles/yr. From looking at different estimates made therein, we advocate D-p <= 0.25 mu m (PN0.25 equivalent) for adopting emission control standards. In volatility analysis flaming combustion and open burning indicated internal mixing of black carbon and organic carbon in emitted ultrafine particles, while smoldering combustion emitted ultrafine particles having little black carbon component. Up to 65% contrast in remaining volume in volatility analysis between the flaming and smoldering combustions, and positioning of open burning in between them, give us the idea of potential management of such biomass burning with controllable distinct choices. Therefore, the concept of exploiting potential from interdisciplinary dimensions is coined to enable more efficient management with least amounts of additional resources utilized, by resolving complexities through mutual cooperation of concerned disciplinary researches. It also shows a new avenue in our affairs in managing global atmosphere for the global ecosystem and public health.