Owing to & Due to

Due to and owing to can be considered adjectival.

• The strike is owing to/due to dismissal of the workers.
• Symptoms due to/owing to dengue can be easily identifiable.

Explanation:

Here, owing to and due to can be considered as it relates to preceding noun in each case- strike and symptoms.

Owing to also functions on its own as a preposition, relating directly to a noun or noun equivalent that follows it ( and forming with it an adverbial phrase of cause and explanation)

Owing to the low price of gold, countrymen are reported to come in volumes to purchase the metal.

Due to can also function like owing to, however, grammarians and purists frown at the use of due to as a preposition.

There is a very good reason for this objection-due to seems to have as much or as little right to an extended grammatical function as owing to- but it is strongly disapproved of, and knowledge of it is often cited as a good test of a person's grasp of standard usage.

The difference in range between due to and owing to can be summed up in this way:

Owing to can usually replace due to, but due to cannot replace owing to. 

You can read due to as- 'CAUSED BY', 'RESULTING FROM, 'ATTRIBUTABLE  TO' 

& 

owing to can be read as ' BECAUSE OF'.

You can use due to only when you can answer the question- What is due?

Look at the following sentence:

•  Dan was barely 48, but due to an unexpected ailment, he was forced to take voluntary retirement.---- incorrect.

Explanation:

In this example 'Due to' DOES NOT relate directly as an adjective to any noun or noun phrase; if you try to replace due to by its equivalent caused by, it becomes clear that there is error in the construction.

Now, look at the following sentence:

• Due to an unexpected ailment, Dan was forced to take voluntary retirement.--- incorrect.

Explanation:

Due to can not be used at the beginning of a sentence- not in this sentence, since it doesn't qualify the noun Dan; again, the substitution of caused by shows how incorrect the sentence formation is.

• Dan's demise, due to/owing to a heart attack, occurred on the very day that he announced his retirement.----correct.

Explanation:

Due to here relates directly to the noun phrase Dan's death, and the substitution of caused by produces a perfectly idiomatic sentence: Dan's death, caused by a heart attack, occurred.......owing to is acceptable too.

Due to a heart attack, Dan's death occurred on the very day that he announced his retirement----somewhat acceptable.

Here, the possibility of a paraphrase beginning caused by a heart-attack, Dan's death....this is one of the rare cases in which due to can begin a sentence correctly-though frowned upon.

• Owing to a heart attack, Dan's demise occurred on the very day he announced his retirement.-----unacceptable.

Explanation:

Even though, owing to is frequently is used at the beginning of a sentence, it is awkward to put it before the relevant noun or noun equivalent, as here, rather than after it.

• All the remaining meetings at the conference are unfortunately, due to circumstances beyond control, postponed until further notice.-----unacceptable.

Explanation:

The verb to be does occur in front of due to, but is not related to it at all; if we substitute due to with caused by, we will understand the faulty construction.

It is not a good idea to ignore the purists' objection to the use of due to as a preposition. Whether it is a fair objection or NOT, it remains a touchstone of people's usage. Careful users of English  adhere to the rule--owing to means because of, due to means caused by - and continue to frown on the breach of it by others, no matter how numerous they may be.