For the cooler months, a snood and mask in one - easily cleaned and filters can be replaced. One of these filters will last one week of continuous use.
 
I recommend: 
PM2.5 Replaceable Filters for Adult (10 PCS)
by WELT
Learn more: https://www.amazon.co.uk/dp/B086WBM2T9/ref=cm_sw_em_r_mt_dp_I1nDFb6F84GJ8