Mr Tse, a senior environment protection official, is fighting against the odds and today we are standing at the most notorious part of the battleground in Causeway Bay, a popular shopping area in the centre of Hong Kong.
Boxes on the side of the road monitor the air quality. They regularly report choking levels of pollution so bad that passers-by have to cover their faces in a vain attempt to fend off the muck that descends from the skies.
Hong Kong is simply too crowded. The city has the highest concentration of vehicles anywhere on earth and the buildings are so tightly packed that the air cannot circulate freely.
The government has been issuing daily bulletins giving the air pollution index since 1996. At the best times, Causeway Bay scores 60 points. This signifies that the air quality is not exactly bad but could produce illness over the long term. Generally, however, the score hovers just below 100 points. Above that, people with heart and respiratory problems are advised to keep well away. At worst, Causeway Bay hits the 160 point mark. Then it is a very unpleasant place indeed.
Causeway Bay also borders Victoria Harbour, famous for the extraordinary skyline surrounding it and junks floating past ocean-going liners. What the tourist pictures do not, and cannot, show is the colour and smell of the water, especially the waters in the Causeway Bay typhoon shelter, where floating gin palaces nestle against wooden fishing vessels and rundown boats serve as home for old sea- faring families.
In the company of David Wong and his Environmental Protection Department colleagues we bob up and down in a tiny sampan to get a bird's eye view of the polluted mess.
Although it does not look too bad, the smell tells another story. The storm drains on the edge of the harbour are supposed to be for rain water. But many waste disposal drains have been illegally linked up to them. Mr Wong's team of investigators are engaged in a time consuming task of identifying where the polluters are located.
The inspectors have some success. However, when we inspect an open sewer designed for storm water I see how difficult the task is. Suddenly the water pouring through the drain turns murky brown. Mr Wong declares that it must be coming from a nearby building site breaking the rules of water disposal. Mobile phones are quickly deployed to get an inspector on the job and find the culprit. It seems another case of putting sticking plasters over a gaping wound.
Protests over the government's lack of enthusiasm for tackling pollution problems are mounting. But there are limits to what the authorities can do. Hong Kong is situated on the tip of China's industrial heartland. Airborne and waterborne pollution knows no boundaries.
Mr Tse looks up. Above him the sky turns into a murky glow as a heady mix of pollutants get together and descend over the territory. "I'm not saying it's not bad, but it's improving," says Mr Tse.
You have to be an optimist in his line of work.