'Shitty Trains' are available in summer on very hot days and they are not comfortable journey's. This is caused by by 'stinky people' that don't look after their body odor which affects his nose (which is sensitive to smelling).
The morning train services are provided with new train carriages, with older train carriages in the afternoon, this is when he tends to suffer with this condition - when you get a sudden putrid smell, this can cause further stress from the work you have carried out during the day as the train carriage becomes uncomfortable, hot sweating & sticky.
What is required is newer train services in the afternoon, which is important, with air circulating with air conditioning, rather than open windows bringing heat all throughout the journey, it makes you more refreshing especially if you are going to meet someone or meeting more people!
Check out website for 'Shitty Rail'