The Department of Health has warned that smoking cannabis can cause users to develop asthma, bronchitis and chronic obstructive pulmonary disease.
Napapan Nanthapong, director of the department's Bureau of Environmental Health, said smokers face developing diseases while children and infants who inhale cannabis smoke face developing psychological problems.
"It can ... trigger more problems for patients with mental illness," she said.
"Studies [also] show that cannabis smoke can emit PM2.5 at an amount 3.5 times higher than normal cigarettes."
"People should realise that smoking marijuana can make their health worse, especially those affected by second-hand smoke," she said.
"Business operators who organise smoking events are asked to control the smoke [so it won't affect] people in the neighbourhood," she added. "Local officials who find such smoking [taking place] can take legal action against those involved."
She said public health officials across the country are duty-bound to educate locals on the dangers of cannabis smoke.
Neeranuch Arphajarat, director of the department's Legal Affairs Division, said smoking cannabis in public is considered a nuisance under a public health announcement that took effect on June 15.
Violators can be reported to the authorities for investigation, she said.
Anyone found guilty of causing disturbance to others while smoking cannabis can face three months in prison and/or be fined up to 25,000 baht, she said.
Cannabis was decriminalised on June 9 but many people have warned of the need for proper legislation to regulate the recreational use of cannabis among young people.
Public Health Minister Anutin Charvirakul, who spearheaded the kingdom's decriminalisation effort, recently hailed the move as good policy, with campaigns in place to ensure the proper use of cannabis.
Currently, the government allows households to grow cannabis after registration, while cannabis product producers must seek a licence and THC content must not exceed 0.2% by weight.
Products containing higher content of THC is considered illegal.