HONG KONG — Hong Kong’s embattled chief executive on Wednesday used his first policy address to outline a series of populist proposals to alleviate the severe housing shortages and air pollution that have bedeviled the city.

The chief executive, Leung Chun-ying — who took office in July and has already weathered one legislative vote of no confidence, one vote to start an impeachment process and a series of large street protests — pledged to help produce 100,000 housing units over the next five years by streamlining approvals, opening undeveloped land for housing and even using rock caverns and other underground spaces for development.

Despite a moderation in apartment prices, demand for housing remains intense, Mr. Leung said.

“Many families have to move into smaller or older flats, or even factory buildings,” he said. “Cramped living space in cage homes, cubicle apartments and subdivided flats has become the reluctant choice for tens of thousands of Hong Kong people.”

Large developments in Hong Kong take 10 to 20 years to approve and build because they involve considerable public consultation, elaborate engineering for building on the city’s steep slopes and sometimes the construction of subway stops. Mr. Leung, 58, cautioned that his suggested measures might not bring quick relief.