Schoolgirl wearing a gas mask in Causeway Bay to protest the high levels of roadside air pollution (30/6/10) (Photo taken for Clean Air Network) c Alex Hofford (

By: Jessica Hefes

Date: 9/8/10

Some groups are more vulnerable to the health effects of air pollution. Children, adults over 45 years of age, and in particular the elderly, and those who live in economically deprived areas are most at risk. [1] Even low amounts of air pollution affect children. It is an average daily high level of pollution that causes damage to children and not simply the uncommon very high pollution days. [2]

Since children have higher breathing rates than adults, they are at greater risk of exposures to pollution. [1] Air pollution impairs the normal development of lung function in children. This can create lifetime defects by the time they reach the age of 18. [3]

Pollution affects children even before birth. Pregnant women are amongst the most “sensitive receivers” of air pollution. Pollutants will enter a pregnant woman’s bloodstream and can reach the foetus’ circulation through the placenta and umbilical cord. [1] This then damages the baby and affects its future life. It has been shown that children exposed to the most pollution before birth scored 4 to 5 points lower on IQ tests than children with less exposure. [4]


  1. 1.0 1.1 1.2 FAQ, Hedley Index - last accessed 9/8/10
  2. Clean air – Clear choices, Department of Community Medicine, HKU; School of Public Health, HKU; The Air Quality Objective Concern Group, Civic Exchange, 15 October 2007 – last accessed 11/8/10
  3. The impact of air pollution on population health, health care and community costs, Department of Community Medicine, HKU, 27 November 2006 - last accessed 7/8/10
  4. Study links prenatal exposure to smog and lower IQ, 20 July 2009 – last accessed 11/8/10