Ticino parliamentarian Nadia Ghisolfi has submitted a motion calling for the law to require separate smoking and non-smoking areas in restaurant terraces and gardens, SRF television reported.
Ghisolfi stresses she wants to protect non-smokers but is not aiming at a total smoking ban.
If passed by the cantonal parliament, Ghisolfi's motion would mean diners wanting to smoke at an outside eating area would have to sit at clearly marked tables.
“The aim is to protect everyone's health, including that of the service staff,” the Christian Democrat told SRF's 10vor10 news programme.
In Switzerland smoking inside eating establishments has been banned for the past 10 years, with those wishing to light up relegated to outside tables.
Thomas Beutler of the Swiss anti-tobacco association AT welcomed Ghisolfi's initiative.
“We know that certain groups of people such as pregnant women, children and those with respiratory illnesses are especially affected by smoke. For these people it is going to be more pleasant to sit outside on a restaurant terrace,” Beutler told the TV programme.
But there was condemnation from the hotel and gastronomy association Gastrosuisse.
The association's president Casimir Platzer said the initiative went too far and would be hard to implement.
Wind could blow smoke from the smokers' section into the non-smoking area, Platzer said.
But he did not dismiss it entirely, saying that cantonal initiatives did often send out signals that were picked up by the federal government.
The Ticino initiative follows similar moves to limit passive smoking in other countries.
In parts of the United States, Canada and Australia regulations on smoking in outdoor restaurant seating areas are in force.
In February, Swiss federal railways SBB announced it was implementing a partial ban on smoking on platforms in a trial at six stations across the country.