According to the Environmental Statistics 2011 released by the Statistics and Census Service (DSEC), total land area of Macao measured 29.9 km2 at the end of 2011, up by 0.7% year-on-year; the population density rose by 1.7% to 18,400 people per km2. Total lane length of public roads was 416.0 km, and the motor vehicle density was 496 vehicles per km, up by 0.6% and 4.2% respectively year-on-year. In 2011, total rainfall decreased significantly by 37.2% year-on-year to 1,363.6 mm; the lowest pH value of rainwater was 3.5 (precipitation with pH value lower than 5.6 is classified as acid rain). Number of days with a Low to Moderate ultraviolet index level increased by 5.3% year-on-year to 337. As regards air quality level, the Northern District monitoring station recorded 294 days of good air quality in 2011, up by 20 days year-on-year, representing five consecutive years of increase; the Rua do Campo monitoring station registered 270 days, down by 19 days year-on-year. The quality of potable water from the distribution network and Water Treatment Plants of Macao conformed to the standard according to the results of the analysis carried out by the Laboratory of the Civic and Municipal Affairs Bureau. The salinity level of potable water was classified as Low in 2011. Volume of domestic garbage collected by the Macau Waste Systems Company Limited rose slightly by 0.5% year-on-year to 166,000 tonnes, while that from the business sector increased by 9.3% to 98,000 tonnes. A total of 329,000 tonnes of garbage were processed in the Incineration Plant, up by 2.4% year-on-year. Volume of waste transported to landfill site for construction materials decreased substantially by 17.2% to 1,618,000 m3. In 2011, the average volume of waste water treated by the 4 Waste Water Treatments Plants in Macau was 186,000 m3 per day, down by 1.2% over 2010. With respect to environmental activities, the Civic and Municipal Affairs Bureau and the Environmental Protection Bureau together collected 447 tonnes of paper, 63 tonnes of plastic materials and 25 tonnes of metallic materials for recycling in 2011; moreover, a total of 1,290 promotional activities were organized, with approximately 538,000 participants.
