Allegations that undocumented workers were used at a Waikiki hotel renovation project, paid below the going rate and exposed to black mold at the work site are unsettling — especially on this Labor Day as the nation honors its workforce.

Last week, the Pacific Resource Partnership (PRP), a construction union advocacy group, alleged labor violations and building irregularities at the $25 million Maile Sky Court renovation project — highlighting the critical need to adhere to labor laws and building regulations.

The city Department of Planning and Permitting acted swiftly by citing the owner for not maintaining safe and sanitary conditions.

“Black mold is evident” at Maile Sky Court, the violation said, noting corrections must be made by Oct. 1.

As troubling as the presence of mold was the allegation that untrained, undocumented workers handled the black mold without protective gear. Kyle Chock, executive director of PRP, said some construction crew members allegedly reported experiencing difficulty breathing, coughing, throat irritation and migraines while working at the operational condominium hotel.

A swift and thorough investigation is urged, so that any improper work conditions can be remedied and the safety of workers is ensured.

Further, investigators from the state Department of Labor and Industrial Relations (DLIR), U.S. Department of Labor Wage and Hour Division and the state Department of Commerce and Consumer Affairs’ Regulated Industry Complaints Office were on site at the Maile Sky Court project last week, looking into whether firms misclassified construction employees as independent contractors and conducted work off the books.

“This is just the union guys screwing around,” said Lee Grossbard, chief operating officer of California-based Clearview Hotel Capital LLC, which bought the property for $76 million in 2015.

PRP, though, said it was not interested in organizing construction workers at Maile Sky Court; its intent was to enforce compliance.

“Hawaii’s working people and law-abiding contractors need to benefit fairly,” said DLIR director Linda Chu Takayama. “When a 40-story property is renovated, laws protecting workers and fair competition must be followed.”

The labor raid, unfortunately, recalled a similar investigation last year at the redeveloped Ala Moana Center, which resulted this spring in several contractors being fined thousands of dollars for widespread violations of labor rules.

Fair treatment and safety for workers and the need for labor- law compliance are especially important now, with the state in the midst of a construction boom.

Construction jobs reached 40,000 in the second quarter of 2016 — the same level as the fourth quarter of 2007 when construction was at its previous peak level — and the construction sector is expected to pick up again during the second half of the year.

The statistics are all pointing to a steady growth for Hawaii’s economy, which ultimately means a healthy jobs outlook, and that’s good news for job seekers.

The state’s unemployment rate during the first seven months of the year averaged 3.3 percent to rank as the fourth-lowest rate in the country.

Still, the state must track the types of jobs available, and continue to stimulate growth of high-paying jobs. National trends show more growth in lower-wage jobs — and while laid-off workers today may find replacement jobs, they are largely at lower wages, according to a recent Forbes article.

That is sobering news indeed on a day set aside for the nation’s laborers. And it reminds that even in Hawaii, which routinely enjoys low unemployment, rankings and economic growth can mask serious issues of quality in jobs and pay, as well as proper treatment of workers.