Leeds Council have warned that the high pollution may cause problems for people outdoors in the city today.
According to the department for Environment Food & Rural Affairs, Leeds is experiencing a 'high' day of air pollution.
Leeds Council has warned this may cause problems for people who are spending time outdoors including causing sore eyes, throat and a cough.
They've especially warned older people to stay inside.
They issued this statement on Twitter: "Due to the 'High' levels of air pollution forecast in Leeds tomorrow, we are sharing the following information.
"Anyone experiencing symptoms such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
"The following groups should reduce physical activity (especially outdoors) where possible: adults with heart problems and adults and children with lung problems.
"If you have asthma, you should carry your inhaler and you may find that you need to use it more often. Older people should also reduce physical exertion."
The council said that this level of air pollution is unusual for Leeds, likely to be short-term and linked to the weather.