Beijing's air pollution worsened further on Tuesday (January 29), deepening public concern about the thick smog which has highlighted the long-term environmental challenges facing the city.<br/> <br />The capital's official air quality monitoring system showed that readings hovered over 400 on an index that measures particulate matter in the air with a diameter of 2.5 micrometers, known as PM2.5.<br/> <br />A level of 300 is considered dangerous while the World Health Organisation recommends a daily level of no more than 20. On January 12, levels exceeded 700, causing a public outcry. Since then, the city's air quality had dipped in and out of the most serious levels of air pollution.<br/> <br />A thick grey pall hung over Chang'an Avenue, the massive, often-congested road which runs through the city centre.<br/> <br />At Beijing's children's hospital, parents holding babies and young children sat in the corridor beside the respiratory illness ward while many children could be seen on intravenous drips.<br/> <br />High levels of PM2.5 can cause cardiopulmonary disease, lung cancer and acute respiratory infection, according to the Journal of Toxicology and Environmental Health.<br/> <br />Many people walking and cycling on the streets were wearing face masks to block out the fumes.<br/> <br />China's state-run media has been unusually vocal about the pollution crisis, calling on authorities to move away from a 'growth at all costs' development model.
