A research team led by an air pollution expert from the Singapore-MIT Alliance for Research and Technology has said that bus stops are hotspots for exposure to tiny particles, which may permeates commuters bloodstream and produce or exacerbate existing pulmonary and cardiovascular diseases.
The expert Dr Erik Velasco said that the size of these tiny particles is estimated to be 27 nanometres in diameter (or 100 times smaller than the PM2.5 reported by NEA). The human hair by comparison is at least 50,000 nanometres thick.
A commuter who makes a two-way bus trip for five days per week, may inhale an average 3.5 times more of these ultrafine particles than at ambient level; and are exposed to these particles while standing at bus stops for nearly 7 hours per month, the study concluded.
Approximately 63% of Singapore’s population commute to work by bus every day. Dr Velasco and a former NUS student Ms Tan Sok Huang who undertook the research since 2011, took measurements of different air pollution parameters at busy bus stops in Singapore. They found that on average, 60 percent of these particles are composed of soot. The rest is a mix of inorganic and organic compounds, in addition to particles with heavy metals. All of them are highly toxic.
The levels ultrafine particles are higher than those reported in bus stops of Canada and United States and similar to those along streets and bus stops of Hong Kong and Mexico City. The study suggests that less than one hour of exposure to these tiny particles exacerbates existing pulmonary and cardiovascular diseases.
The five bus stops in which the research was conducted included those at VivoCity, Little India, Bugis, One Raffles Quay and the National University of Singapore (in front of the university sports fields).