Earlier this month, the Environmental Protection Department announced that the ex gratia payment scheme to phase out diesel commercial vehicles that fail Euro IV emissions standards would be extended for six months, past the December 31 deadline. This was announced as part of Hong Kong’s economic relief package . But the public may not be aware of the true health costs of such an extension. In 2014, HK$11.4 billion (US$1.46 billion) was approved for use in the scheme , with the purpose of phasing out all 82,000 pre-Euro IV diesel commercial vehicles. These include goods vehicles, public light buses and non-franchised buses – the main culprits of Hong Kong’s roadside pollution, according to the government. One key outcome would be to reduce by half the cancer risks due to exposure to diesel engine exhaust. By February this year, there were still 18 per cent or about 14,800 eligible pre-Euro IV vehicles which had not applied the scheme. These vehicles are of the lower Euro III standard, and are already 13 to 19 years old. According to the current regulation, which was put into effect in 2014 to set a service life limit of 15 years for diesel commercial vehicles, some of these (aged 15 years or above) should have been retired already. They are still running and emitting pollutants simply because they were first registered before the regulation came into effect. These vehicles would also be the key beneficiaries of the Environmental Protection Department’s decision to extend the deadline of the scheme. According to government data, Euro III diesel commercial vehicles emit more respirable suspended particulates (RSP) and nitrogen oxides (NOx) than Euro IV vehicles, by 5 and 1.4 times respectively. These are also high-mileage vehicles which serve throughout the city, including areas near schools, hospitals, elderly centres and homes, thus affecting most of the population. How should the public health or cancer risk be assessed, with the additional exposure to the diesel exhaust emitted by these vehicles? What are, then, the corresponding government measures to address the additional health care burden? Are the vulnerable and general public aware of the dangers? Clearly, the Environmental Protection Department has failed to communicate transparently with the general public and other stakeholders before making the decision. The government may have the power to impose administrative measures, but the people also have the right to understand the potential health risks they are exposed to in their daily lives. Patrick Fung, CEO, Clean Air Network