filter

Online, people are calling the colours "hero green" and "brave pink", and many are customising their social media profile pictures with filters in those shades.

Dr Freestone says instances like this can be avoided if the air-con units are of good quality, kept clean and has its filters changed regularly in line with manufacturers' guidance.

"I don't really notice it and filter it out, but I do appreciate that maybe for people who are staying here and who are not used to it that it might stand out," they said.

“Hey, Mom,” he said, holding a cigarette burned down to the filter.

The San Diego County Air Pollution Control District has been providing home air purifiers to residents, and Rico said these efforts should be stepped up to ensure everyone in the area has gas-scrubbing air filters.