Some scholars have issued fatwas saying that it is permissible for these people not to fast. I sent the fatwa to Shaykh ‘Abd-Allaah ibn Muhammad ibn Humayd and Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on them) for their comments on it and they said:  

The basic principle is that it is obligatory to fast Ramadaan, and to form the intention to fast from the night before, for all adult Muslims, who should start the day fasting, except for those to whom the Lawgiver has granted a concession, who are allowed not to fast – namely the sick, travellers and those who come under those headings. Those who do hard work come under the heading of those who are obliged to fast and they are not like the sick or travellers. They have to form the intention to observe the Ramadaan fast from the night before, and to start the day fasting. If one of them is forced to break the fast during the day, then it is permissible for him to break the fast with enough to ward off any harm, then he must refrain from eating and drinking for the rest of the day, and he has to make up that fast at the proper time. If there is no such necessity then it is obligatory to complete the fast. This is what is indicated by the shar’i evidence from the Qur’aan and Sunnah, and it is what is indicated by the words of the scholars of all madhhabs. 

Those in positions of authority among the Muslims among whom are people who do hard work should examine their case when Ramadaan comes, and if possible, they should not burden them with too much work that may force them to break the fast during the day in Ramadaan, rather they should have the work done at night, or distribute work hours in a fair and just manner so that people may both work and fast. 

As for the fatwa referred to, this has to do with an individual case where they issued a fatwa based on their ijtihaad for which they are to be appreciated, but they did not mention the conditions that we have mentioned or the view of the scholars of all madhhabs. We ask Allaah to help us all to do that which is good. End quote. 

Shaykh ‘Abd-Allaah ibn Muhammad ibn Humayd (may Allaah have mercy on him). 

Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on him). 

Majmoo’ Fataawa Ibn Baaz, 14/245 

And Allaah knows best.