Why I am having eye irritation problem with oil radiator in my home (in India/Asia) when I never had such problem in Europe

Probably paint on the outside of it off-gassing something.

Set it outside and run it on high for a few hours, that might help burn the volatiles off.

Most are too convoluted to expect removing the paint to be practical.

Without sounding demeaning or condescending countries don't all have similar laws and standards that industry must abide by in which to protect their citizenry.

What one Eastern country's government dictates as "safe to use" for the consumer may differ radically from a similar company in the West. Indeed, industry standards may further differ in a country by state or prefecture. In one state environmental laws are more lenient than those in another (west coast) state.

Substances and chemicals used in any type of product are tested for toxicity. Depending on your governments policies and standards these chemicals may not be considered dangerous. Or their notion of testing for harmful substances may be wanting.

This link gives stats and rates for consumer products: stats and safety