First, write a greeting to your friend.
Then, notice that you friend's surroundings are haze-bound. Therefore, it is a privilege for you to help your friend on how to stay healthy when there is haze around.
Just tell your friend to avoid playing outdoors nor to be outside of the house for a long time. Wear a mask to avoid breathing difficulties. Remind your friend that you care about your friend's health and wish he/she to be at home.
Hope this helps.