What steps were taken to clean London in the early and mid-20th century? Write four points

What steps were taken to clean London in the early and mid-20th century? Write four points.
Ans. Several steps were taken to clean up London, attempts were made to decongest localities, green the open spaces, reduce pollution and improve landscape of the city. These were
(i) Large block of apartment were built. It has been proved that housing scheme brings a magical change in the urban area where land is very important.
(ii) Green belt was created around London. Demands were made for new lungs for the city and some attempts were made to bridge the differences between city and countryside by making Green belt around London.
(iii) Rent control was introduced to check housing shortage.
Large scale of migration from rural areas to cities made a severe housing problem. By introducing rent control, government tried to prevent illegal demand of rent from the working class poor people.
(iv) Many working class people shifted to suburbs of London. Suburbs were well planned and well connected with London. Suburbs helped to decongest London.
(v) One million single family cottages were built for the working class by local authorities.