The phrase 'unhygienic environment' is correct and usable in written English. You can use it when you wish to refer to an environment that is not clean or sanitary. For example, "The factory had an unhygienic environment, which posed a health risk to its workers.".
Children are often delivered in an unhygienic environment without a nurse, doctor or midwife.
The disease is commonly spread from child to child in an unhygienic environment.
"Safe water and sanitation are human rights and, along with hygiene, they improve health and productivity, help keep girls in school, and can save the lives of new mothers and their newborns who might otherwise die of infections from being born in an unhygienic environment".
The lake area is also misused as public toilets leading to unhygienic environment and increasing the organic load in the lake.
That has led health experts to conjecture that the infection was common in earlier times but that people were exposed and infected (in typically unhygienic environments) at very young ages, when they were less likely to suffer permanent paralysis as an outcome.
Further, the quality-of-life data indicate that health care in public and NGO sectors may be taking place in less sound, more unhygienic environments than in the private sector.
Repeated bouts of diarrhea are directly linked to malnutrition and are caused by dirty water and unhygienic environments.
Ludwig does not simply clarify my doubts with English writing, it enlightens my writing with new possibilities
Simone Ivan Conte
Software Engineer at Adobe, UK